Best Cummins 5000W Inverter Generators for 2026

The AMERISUN 5000W Portable Inverter Generator is a mid-range power solution designed for homeowners seeking reliable backup electricity, RV enthusiasts needing mobile power, and outdoor enthusiasts who require clean, dependable energy. With its 223cc OHV engine and inverter technology, this generator bridges the gap between budget models and premium commercial units.

The standout feature is its clean power output, maintaining less than 3% Total Harmonic Distortion to safely charge phones, laptops, and tablets without risk of damage. Early users consistently praise its quiet operation, comparing it to a sewing machine. The 10-hour runtime at half load provides extended operation between refueling, while the diverse outlet configuration, including a 30A RV outlet, 4 standard 120V outlets, 12V DC, and dual USB ports, accommodates various power needs simultaneously.

Build quality appears solid based on user feedback, with reports of clean oil after initial operation and reliable startup performance. The pull handle design receives positive marks for ease of use. The generator includes comprehensive safety features: carbon monoxide protection, overload detection, overheat shutdown, and low-oil auto-shutoff. EPA and ANSI certifications validate these safety claims.

The main limitation is weight at 89 pounds, which challenges the portable classification despite compact dimensions. Additionally, while most users report quick starts, some mention requiring multiple pulls under certain conditions. Heavy-load performance data remains limited in available customer feedback, so potential users planning sustained high-wattage operation should verify compatibility.

The AMERISUN 5000W represents excellent value for backup power and RV applications, backed by a 2-year warranty and proven reliability. It excels for users prioritizing quiet operation, device safety, and convenient portability over maximum power output.

Power Output: 5000 starting watts, 4000 running watts

Engine: 223cc OHV 4-stroke with magneto ignition

Fuel Capacity: 3.43 gallons (13 liters)

Runtime: Up to 10 hours at 50% load

Power Quality: Less than 3% THD clean power

Outlets: 4x 120V 20A AC, 1x 120V 30A RV (NEMA L5-30R), 1x 12V DC, 2x 5V USB

Dimensions: 26 inches L x 19 inches W x 22 inches H

Weight: 89 pounds

Certifications: EPA, ANSI G300, UL2201

Warranty: 2 years

Model: AM5046C

Who Should Buy This Generator? This model suits homeowners needing backup power during outages, RV owners requiring mobile electricity, camping enthusiasts seeking quiet operation, and anyone prioritizing device safety over maximum wattage.

Power Capacity Considerations: With 4000 running watts, this generator handles most household essentials: refrigerators, microwave ovens, power tools, and multiple devices simultaneously. It may struggle with simultaneous high-demand appliances like air conditioning units or electric heaters.

Maintenance Tips: Use non-ethanol gasoline for optimal performance and longevity. Change oil after initial 20-hour break-in period, then follow regular maintenance schedules. Store fuel properly during off-seasons to prevent degradation.

Setup Recommendations: Place the generator on level ground, at least 20 feet from windows and doors to minimize carbon monoxide exposure. Ensure proper oil levels before each use. Allow 30 minutes of runtime during initial operation to verify smooth function.

Noise Expectations: At approximately 70-80 decibels, this generator operates quieter than most competitors, making it suitable for residential neighborhoods and campgrounds with noise restrictions.

The Oxseryn 5000W inverter generator is a versatile portable power solution designed for RV enthusiasts, homeowners needing emergency backup power, and professionals requiring reliable job-site electricity. With 5000 peak watts and 4000 running watts, it handles the power demands of appliances, power tools, and sensitive electronics with equal capability.

This generator excels in real-world performance through its inverter technology, which delivers clean, stable power with low harmonic distortion. Users consistently report reliable cold starts and appreciate the ECO mode feature that reduces both noise levels and fuel consumption during extended use. The 10-hour runtime at 25% load combined with a 2-gallon fuel tank and visible fuel gauge means fewer interruptions and better planning for extended outdoor activities.

Built for durability and portability, the Oxseryn weighs only 59 pounds with a compact 19-by-15-by-18.5-inch footprint. The sturdy open-frame construction withstands outdoor environments, while the 223cc 4-stroke engine provides dependable power in various conditions. Multiple outlet options, including a 30A RV outlet, two 120V AC ports, and a 12V DC port, ensure compatibility with most applications.

The primary consideration is noise level. Operating at 70 dBA measured 23 feet away, it performs quieter than many competitors, but some campers may still find it audible during evening use. Additionally, the lightweight design means the unit may shift during the pull-start process, requiring you to stabilize it with your leg or hand for smooth operation.

The Oxseryn 5000W inverter generator offers excellent value for users prioritizing fuel efficiency, portability, and clean power output. It's an outstanding choice for RV camping, emergency home backup, and professional outdoor work, backed by a 1-year manufacturer warranty and consistently positive user feedback.

Power Output: 5000 peak watts, 4000 running watts, 60 Hz frequency
Engine: 223cc 4-stroke OHV engine with magneto ignition and cold-start technology
Fuel Tank: 2 gallons (7.57 liters) with fuel gauge
Runtime: 10 hours at 25% load
Outlets: 1x 30A RV outlet, 2x 120V AC outlets, 1x 12V DC port
Noise Level: 70 dBA at 23 feet
Weight: 59 pounds
Dimensions: 19 inches L x 15 inches W x 18.5 inches H
Features: Inverter technology, ECO mode, low oil shutdown, overload protection, fuel efficient
Warranty: 1 year manufacturer warranty
Included: Oil funnel, screwdriver, socket wrench, user manual

Is This Generator Right for You? The Oxseryn 5000W is ideal if you need a portable, fuel-efficient generator for RV camping, emergency home backup, or outdoor work. Its inverter technology makes it safe for laptops, phones, and cameras. Consider this model if you value quiet operation, easy starting, and long runtime between refueling.

Power Requirements: To determine if this generator meets your needs, add up all running watts of devices you'll use simultaneously, then add starting watts (typically 2-3x running watts for motors). The 4000 running watts handles most household appliances, but air conditioning units may require the full 5000 peak watts for startup. For larger loads, Oxseryn offers parallel-capable models in other sizes.

High-Altitude Use: This generator operates at high altitudes but may experience reduced performance. Oxseryn recommends installing a high-altitude kit to adjust the air-fuel mixture and prevent spark plug fouling in mountain environments.

Maintenance Tips: All Oxseryn generators undergo factory testing, so minor gasoline residue is normal. Change oil regularly, use fresh fuel, and store with stabilizer during off-season. The sturdy frame and protective design support long-term reliability with basic maintenance.

The Westinghouse iGen5000 is a mid-range inverter generator designed for RV enthusiasts, camping adventures, and emergency home backup power. It bridges the gap between budget-friendly models and premium-priced competitors, offering serious power capacity without the four-figure price tag. This generator appeals to off-grid campers, travel trailer owners, and homeowners seeking reliable backup power for essential appliances.

The standout feature is its impressive 18-hour runtime combined with remote electric start capability. The 5000 peak watts and 3900 continuous watts can handle air conditioning units, microwave ovens, battery chargers, and multiple devices simultaneously, a significant upgrade over smaller 3000-watt models. The inverter technology maintains ultra-clean power output below 3% THD, making it safe for sensitive electronics like laptops and modern televisions. Real-world user feedback confirms that this unit runs quieter than expected at 52 dB and starts reliably with the included wireless key fob.

Build quality reflects Westinghouse's solid engineering, with a 4-stroke engine, sturdy frame, and thoughtful design touches like the LED data center display showing fuel level, power consumption, and maintenance hours. The telescoping handle and wheels make transport manageable for a 105-pound unit, though moving it still requires two people. The RV-ready TT-30R outlet, dual household outlets, and USB ports provide comprehensive power distribution for modern camping setups.

The primary limitation is the gap between peak and running wattage, meaning you cannot continuously run all your appliances at maximum capacity simultaneously. Additionally, gas-powered generators require regular maintenance, seasonal fuel stabilization, and proper storage procedures. Noise levels, while respectable, are not silent like some premium models.

The Westinghouse iGen5000 represents exceptional value for buyers who prioritize runtime, remote start convenience, and clean power output. Customer reviews consistently praise its reliability and performance, with many noting they replaced more expensive brands and never looked back. This is a smart choice for serious RV users and those needing dependable backup power without premium pricing.

Power Output: 5000 peak watts, 3900 rated watts at less than 3% THD

Engine: 4-stroke, 224cc displacement, 60Hz frequency

Fuel: Gasoline, 3.4-gallon tank capacity

Runtime: Up to 18 hours on full tank with economy mode

Starting: Electric start with remote key fob, recoil backup

Outlets: TT-30R RV outlet (30A), two 5-20R household outlets (20A each), two USB ports

Noise Level: 52 dB (extremely quiet for this wattage class)

Weight: 104.7 pounds with wheels and handle

Dimensions: 24.5L x 17.5W x 20H inches

Warranty: 3-year limited warranty with nationwide service network

Who Should Buy This Generator? RV owners, campers with travel trailers, off-grid homeowners, and anyone needing reliable backup power for 3-5 essential appliances simultaneously. If you've outgrown 3000-watt models but don't need professional 7000+ watt units, this fills the perfect middle ground.

Best Use Cases: Extended camping trips where fuel efficiency matters, powering RV air conditioning and appliances, emergency home backup during outages, charging battery banks for off-grid solar systems, and outdoor events requiring clean power for electronics.

Key Decision Factors: Consider this model if remote start convenience is important to you, if 18-hour runtime between refueling appeals to you, or if you need RV-ready connections. Skip this if you need continuous power for heavy equipment, require silent operation, or prefer premium brand loyalty.

Maintenance Expectations: Plan for annual oil changes, seasonal fuel stabilization before storage, spark plug inspection, and air filter cleaning. Proper maintenance extends engine life significantly and ensures reliable starts when needed most.

The Westinghouse iGen5000c is a premium inverter generator designed for RV owners, camping enthusiasts, and homeowners seeking reliable backup power. This 5000-watt unit combines portability with serious power output, making it suitable for both recreational and emergency applications. At its core, this generator delivers the kind of dependable performance that justifies its investment.

What truly sets the iGen5000c apart is its commitment to quiet operation paired with exceptional fuel efficiency. Running at just 52 dB with less than 3% total harmonic distortion, this generator produces clean power safe for sensitive electronics like laptops and plasma televisions. The 18-hour runtime on a 3.4-gallon fuel tank means you can power your RV or campsite through an entire day and night without refueling, while the variable engine speed automatically adjusts output to match your actual power needs.

The build quality reflects Westinghouse's reputation for durability and engineering excellence. The telescoping handle and wheeled design make transport manageable despite the 105.8-pound weight. The LED data center displays real-time information including fuel level, power output, runtime remaining, and lifetime hours, helping you maintain the unit properly. Automatic low-oil and CO shutdown sensors provide critical safety protection, particularly valuable for enclosed space operation.

The versatile outlet configuration is genuinely practical for modern power needs. The RV-ready TT-30R 30A outlet handles large appliances and AC units, dual 120V household outlets support standard devices, and USB ports charge phones and tablets directly. Remote electric start with included key fob makes cold-weather ignition effortless, while the backup recoil start ensures you can always start the generator manually if needed.

Minor considerations include somewhat complex oil changes and the potential for LED display issues after extended use, though these are uncommon. The 105.8-pound weight may challenge solo users during transport. Despite these minor points, customer feedback consistently praises reliability, with reported usage exceeding 333 hours without issues. This generator delivers exceptional value for users who prioritize quiet operation, fuel efficiency, and dependable power for RVing or backup applications.

Power Output: 5000 peak watts, 3900 rated watts at less than 3% THD

Engine: 4-stroke gas-powered engine with electric start, recoil backup, and auto choke

Fuel Tank: 3.4 gallons with economy mode for up to 18-hour runtime

Outlets: TT-30R RV 30A outlet, two 120V 20A household outlets, two USB ports (5 total)

Voltage Output: 120V at 60 Hz

Noise Level: 52 dB

Dimensions: 24.5L x 17.5W x 20H inches

Weight: 105.8 pounds with telescoping handle and wheels

Safety Features: Automatic low-oil shutdown, CO sensor with automatic shutdown, overload protection, voltage regulation

Warranty: 3-year limited warranty with lifetime technical support

RV and Camping Enthusiasts: The RV-ready 30A outlet and 18-hour runtime make this ideal for travel trailers and motorhomes, providing reliable power for air conditioning, refrigeration, and entertainment systems during dry camping.

Home Emergency Backup: Clean power output and automatic safety shutdowns protect your home electronics during outages. The quiet operation means neighbors won't be disturbed during extended power loss situations.

Outdoor Work and Events: Construction crews, outdoor events, and landscaping professionals benefit from the combination of serious power output and portability. Run power tools and equipment without constant refueling.

Off-Grid Living: The exceptional fuel efficiency and long runtime support cabin owners and off-grid homeowners who need reliable backup power between solar charging or generator runs.

Sensitive Electronics Protection: Content creators, photographers, and professionals with expensive equipment appreciate the clean, stable power output that safeguards laptops, cameras, and other sensitive devices.

The Westinghouse iGen5000DFc is a premium dual fuel inverter generator engineered for recreational users, RV enthusiasts, and homeowners seeking dependable backup power. With 5000 peak watts and 3900 rated watts output, this generator handles essential household appliances, power tools, and sensitive electronics without compromise. The dual fuel capability makes it equally valuable for weekend camping trips and emergency home use.

Performance standout features include whisper-quiet operation at just 52 dB, making it suitable for campgrounds with noise restrictions and residential neighborhoods. The inverter technology maintains clean power at less than 3% THD, protecting laptops, tablets, smartphones, and entertainment systems from damage. Runtime reaches an impressive 18 hours on a single 3.4-gallon tank in economy mode, reducing refueling frequency during extended use.

Design and portability shine with the suitcase-style telescoping handle and built-in wheels that make moving this 105-pound unit manageable for most users. The LED data center provides real-time information including fuel level, power output, runtime remaining, and voltage output. Five total outlets including an RV-ready TT-30R connector, two household 120V outlets, and dual USB ports accommodate multiple devices and appliances simultaneously.

The remote electric start with included wireless key fob offers genuine convenience, though the backup manual recoil start ensures operation if batteries fail. Automatic safety shutdowns for low oil and carbon monoxide detection provide peace of mind during unattended operation. Some users note the 3.4-gallon tank requires refueling during sustained high-load use, a minor tradeoff for the compact portable design.

This generator earns strong recommendation for anyone prioritizing quiet operation, fuel efficiency, and versatile power connectivity. The 3-year warranty and nationwide Westinghouse service network provide confidence in long-term reliability and support.

Power Output: 5000 peak watts, 3900 rated watts at less than 3% THD
Fuel Type: Gasoline and Propane (dual fuel capable)
Engine: 224cc 4-stroke engine with variable speed control
Starting System: Electric start with wireless remote key fob, manual recoil backup
Runtime: Up to 18 hours on 3.4-gallon gas tank in economy mode
Noise Level: 52 dB (less than most competitors)
Outlets: One TT-30R RV outlet, one 5-20R household outlet, two USB ports
Weight: 105.8 pounds
Dimensions: 24.5 inches length x 17.5 inches width x 20 inches height
Warranty: 3-year limited coverage with lifetime technical support

Who Should Buy This Generator: RV owners needing reliable power for 30-amp systems, campers prioritizing quiet operation, homeowners seeking emergency backup power for essential appliances, and anyone running sensitive electronics that require clean stable power.

Key Considerations: Verify your power needs total below 3900 watts for continuous operation. Check local noise ordinances if using in residential areas, though 52 dB is exceptionally quiet. Confirm whether you have propane infrastructure available if selecting dual fuel capability. Consider storage space for the 105-pound unit and whether wheels and handle meet your portability needs.

Maintenance Tips: Follow the detailed owner manual for initial oil setup, as the engine requires less oil than the included bottle provides. Change oil after break-in period and regularly. Store with fuel stabilizer or drain tank before extended storage. Keep air filter clean and battery charged for reliable remote start operation.

The Cummins Onan P4500I is a portable inverter generator designed for RV owners, campers, and homeowners seeking reliable backup power. This 4500-watt unit combines portability with serious power generation, weighing just 98 pounds while delivering consistent 3700 watts of clean, stable electricity. It's ideal for anyone who needs dependable power away from grid connections or during emergencies.

The standout feature is undoubtedly the remote start capability, which lets you fire up the generator from inside your RV or tent on cold mornings. Powered by a robust 7.3 HP 224cc OHV 4-stroke engine, it runs remarkably quiet and delivers an impressive 18-hour runtime on its 3.4-gallon fuel tank. The inverter technology provides clean power safe for sensitive electronics, while dual 5V USB ports and a 30A TT-30R outlet cover most charging and appliance needs.

Build quality reflects Cummins' reputation for durability. The metal construction feels solid, and the compact design fits easily in truck beds or RV storage compartments. Owners consistently praise the quiet operation and reliable starting, even in extreme cold conditions. The parallel capability allows stacking two units for 50A output, providing future scalability if your power needs grow.

The main limitation is that 3700 watts of running power won't simultaneously run large appliances like full-size air conditioners. Initial setup requires adding oil and connecting the battery before first use, adding a small barrier for complete beginners. Some users reported initial issues, though customer support appears responsive.

Overall, the Cummins Onan P4500I delivers excellent value for serious outdoor enthusiasts and homeowners needing portable, quiet backup power. The remote start alone justifies consideration, and the proven reliability makes this a smart investment for long-term use.

Power Output: 4500 watts starting, 3700 watts running

Engine: 7.3 HP 224cc OHV 4-stroke, electronic ignition

Fuel: Gasoline, 3.4-gallon tank capacity

Runtime: 18 hours at rated load

Outlets: 30A TT-30R outlet, dual 5V USB ports, total 3 outlets

Voltage: 120 volts, 50 Hz frequency

Weight: 98 pounds

Dimensions: 24.5 inches L x 18.25 inches W x 20.5 inches H

Features: Remote start, pull cord backup, fuel efficient, overload protection, super quiet operation

Warranty: 3 years

Who Should Buy This? RV owners, campers, and homeowners seeking portable backup power will appreciate the remote start and quiet operation. The 3700-watt capacity handles most camping appliances, small AC units, and power tools. It's perfect for those who value convenience and reliability over maximum power output.

Who Should Look Elsewhere? If you need to run large appliances simultaneously or require more than 3700 watts, consider larger portable generators. Budget-conscious buyers may find less expensive options, though they typically sacrifice the remote start and quiet operation advantages.

Setup Tips: Allow time for initial oil filling and battery connection before first use. Read the manufacturer instructions carefully. Store in a dry location and run regularly to keep fuel fresh. The 18-hour runtime means less frequent refueling on extended trips, a major convenience factor.

Value Proposition: The combination of remote start, exceptional quiet operation, proven Cummins reliability, and 18-hour runtime justifies the premium price. This generator pays dividends through convenience and peace of mind, particularly for frequent travelers and outdoor enthusiasts.

The Cummins Onan P2500i is a portable inverter generator designed for campers, RV owners, and homeowners seeking reliable backup power. With 2200 running watts and 2500 peak watts, it handles essential household appliances, camping equipment, and sensitive electronics without compromise. This generator is built for users who prioritize portability and fuel efficiency over maximum power output.

What sets this model apart is its exceptional quiet operation and remarkable fuel economy. Users consistently report that the generator runs smoothly and quietly, making it suitable for campgrounds with noise restrictions and residential neighborhoods. The eco-mode feature stretches runtime to 12 hours on a single tank, significantly reducing refueling interruptions during extended trips or emergency situations. The digital inverter technology ensures safe power delivery to phones, tablets, and laptops, protecting them from voltage fluctuations.

The 56-pound construction strikes an excellent balance between portability and durability. The 3.4 HP 4-stroke engine features straightforward pull-start operation and a comprehensive LED display that tracks fuel level, power output, voltage, and cumulative runtime hours. Four total power outlets, including two 5V USB ports, provide versatile charging options for modern devices and appliances. The build quality reflects Cummins' reputation for dependable equipment.

The main limitation is the 1-gallon fuel tank, which requires refueling every 10-12 hours under typical conditions. Additionally, at 2200 running watts, simultaneous operation of multiple high-demand appliances like air conditioners or power tools may exceed capacity. The pull-start mechanism could challenge users with limited physical strength compared to electric-start alternatives.

The Cummins Onan P2500i delivers exceptional value for recreational users and emergency backup needs. Its combination of quiet operation, fuel efficiency, inverter protection, and proven reliability makes it an outstanding choice for camping enthusiasts and homeowners seeking dependable portable power. The 3-year warranty provides additional peace of mind for this investment.

Engine: 3.4 HP 98cc OHV 4-stroke, compression ignition, pull-start with recoil rope

Power Output: 2200 watts running, 2500 watts peak, 5 volts USB output

Fuel System: Gasoline powered, 1-gallon tank capacity, up to 10-12 hours runtime

Outlets: 4 total power outlets including 2 USB 5V ports for device charging

Display: LED digital display with fuel level, power output, voltage, remaining runtime, and lifetime hours

Dimensions and Weight: 23 inches length, 21 inches width, 14 inches height, 56 pounds total weight

Frequency: 50 hertz, 3-year manufacturer warranty

Who Should Buy: This generator is ideal for camping enthusiasts, RV owners, tailgaters, and homeowners needing emergency backup power. It works well for powering small appliances, outdoor equipment, and sensitive electronics that require clean, regulated power.

Best Use Cases: Camping trips, RV travel, outdoor events, home backup during short power outages, emergency preparedness, and powering tools at remote job sites.

Considerations: If you need continuous power beyond 10-12 hours, plan for fuel storage and refueling breaks. For high-demand applications like running central air conditioning, consider models with higher wattage ratings. The pull-start mechanism works reliably but may require assistance for users with limited strength.

Maintenance: Regular fuel stabilization during off-season storage and periodic air filter cleaning will extend engine life. The straightforward design makes basic maintenance accessible to most users without professional service.

The Oxseryn 5000W portable inverter generator is a compact, fuel-efficient power solution designed for homeowners seeking backup power during outages, RV enthusiasts requiring reliable campground electricity, and outdoor workers needing portable job site power. With 4000 running watts and 5000 peak watts, it handles essential household appliances, camping equipment, and power tools within its capacity range.

This generator excels with its inverter technology that produces clean power output with total harmonic distortion below 5%, making it safe for sensitive electronics like laptops, phones, and medical devices. The ECO mode intelligently adjusts engine speed based on demand, extending runtime to 6 hours at 50% load on just 2 gallons of fuel. The 30A RV outlet provides direct connection to recreational vehicles, while dual 20A outlets and a 12V DC port offer flexibility for various applications.

Build quality is solid with a durable metal open frame design weighing 60 pounds, making it portable yet substantial. The unit features cold start technology and recoil ignition for reliable startup, plus automatic shutdown protection and overload safeguards. At 70dB from 23 feet away, it operates quietly enough for residential areas and campgrounds where noise restrictions apply.

Potential drawbacks include the relatively small 2-gallon fuel tank, which limits runtime beyond 6 hours without refueling, and some reported startup inconsistencies that may require troubleshooting. The oil level specifications are not clearly marked on the unit itself, requiring manual checking during initial setup. However, customer service is responsive to issues and provides good support.

Overall, the Oxseryn 5000W inverter generator offers excellent value as a reliable, quiet, and fuel-efficient portable power solution. It delivers on its promises for home backup, RV camping, and outdoor use, with proven performance from satisfied customers who appreciate its ease of use and dependable operation.

Power Output: 5000 watts starting, 4000 watts running
Fuel Type: Gasoline, 2-gallon (7.5L) tank capacity
Engine: 4-stroke OHV, 0.16-gallon (0.6L) oil capacity
Start Type: Recoil with cold start technology
Outlets: 1x 30A AC, 2x 20A AC, 1x 12V DC
Voltage: 120V, 60Hz
Runtime: Up to 6 hours at 50% load
Noise Level: 70dB at 50% load from 23 feet
Weight: 60 pounds
Dimensions: 19 inches L x 15.6 inches W x 19 inches H
Features: Inverter technology, ECO mode, automatic shutdown, overload protection, fuel gauge
Warranty: 2-year manufacturer coverage

Is This Right for You? Choose this generator if you need reliable backup power for home outages, plan RV camping trips, or require portable power for outdoor events and job sites. The 4000-watt running capacity supports refrigerators, lighting, microwave ovens, power tools, and most household appliances within its limits.

Power Requirements: Before purchasing, calculate your total running wattage needs by adding up all devices you plan to run simultaneously. Starting wattage can be 2-3 times higher than running wattage for motors and compressors, so ensure your peak loads do not exceed 5000 watts.

RV Compatibility: The 30A outlet is standard for most RV hookups. Always verify your RV's electrical requirements and amperage rating before connection to ensure safe operation and prevent damage to sensitive RV systems.

Maintenance Tips: Check oil levels before each use using the manual method, change oil after the first 20 hours of operation and every 100 hours thereafter, use fresh fuel with stabilizer for storage, and run the generator monthly if not in regular use to keep the engine healthy.