The Complete RV / Motorhome Maintenance Guide

RV engines work harder than car engines. They carry thousands of extra pounds, climb grades, and often sit idle for weeks between trips. Both factors demand attention to oil quality and change intervals.

Gas chassis (Ford, GM): Change oil every 5,000-6,000 miles or every 6 months. Use the weight specified on the oil cap or in your owner's manual, typically 5W-30 or 5W-20.

Diesel chassis (Cummins, Cat, Freightliner): Change oil every 6,000-10,000 miles depending on usage. Diesel engines require CK-4 rated oil, typically 15W-40. Full-timers who put on miles quickly should stick to the shorter interval.

What to watch for:

• Oil that looks milky: indicates coolant contamination
• Excessive oil consumption between changes
• Metal particles on the drain plug magnet
• Dark, gritty oil well before the change interval

RV transmissions handle enormous loads, especially on mountain passes and during towing. Regular service prevents the most expensive repair an RV owner can face.

Allison transmissions (common in diesel pushers): Change fluid and filter every 25,000 miles or 2 years. Use only Allison TES 295-approved fluid. These transmissions are robust but unforgiving when neglected.

Ford/GM automatic transmissions: Service every 30,000 miles. Many gas chassis RVs use the same transmissions as trucks, but work them much harder due to the additional weight.

Transfer case and differential (4WD camper vans): Service every 30,000 miles. Use the correct GL-5 gear oil per manufacturer spec.

Warning signs of transmission trouble:

• Delayed or harsh shifting
• Slipping between gears under load
• Transmission temperature warnings on the dash
• Burnt smell from the transmission fluid

A fully loaded Class A motorhome can weigh 30,000 pounds or more. Your braking system is the most safety-critical system on the vehicle and deserves frequent inspection.

Brake pads and rotors: Inspect every 6,000 miles. Mountain driving, especially descending grades, dramatically accelerates brake wear. Use engine braking (lower gears) and exhaust brakes to reduce pad wear.

Brake fluid: Flush every 15,000 miles or annually. Moisture in brake fluid lowers the boiling point, which can cause brake fade on long downhill grades.

Suspension: Inspect air bags, shocks, leaf springs, and leveling jacks at least annually. Worn shocks cause excessive body roll and poor handling.

Tire care:

• Check pressure before every trip, cold, with a quality gauge
• RV tires age-out even with good tread. Replace at 5-7 years regardless of mileage
• Inspect sidewalls for weather-checking and cracking
• Rotate tires per chassis manufacturer schedule (typically every 6,000-8,000 miles)

RV engines run hot, especially when climbing grades in summer heat. A well-maintained cooling system prevents the most common cause of roadside breakdowns.

Coolant flush: Every 30,000 miles or 2 years. Use the coolant type specified by your chassis manufacturer. Mixing types causes gel formation and clogs.

Regular checks: Inspect coolant level and condition at every oil change. Look for discoloration, oily film, or low levels that indicate a leak.

Components to inspect:

• Radiator hoses: squeeze for soft spots or bulging
• Heater hoses, often overlooked and prone to failure
• Water pump: listen for bearing noise, check for weeping
• Thermostat: replace if engine runs too cool or too hot

RV generators (Onan/Cummins is the most common brand) are small engines with their own maintenance schedule, separate from the chassis engine.

Oil change interval: Every 150 hours of run time or every 6 months, whichever comes first. If your generator has an hour meter, use it to track intervals.

Oil type: Most Onan generators use SAE 30 or 10W-30. Check your generator's manual. Using the wrong weight can cause starting problems and premature wear.

Oil filter: Replace at every oil change. Generator oil filters are small and inexpensive. There is no reason to skip this.

Exercise routine:

• Run the generator under load for at least 2 hours every month
• Running without a load does not exercise the generator properly
• Turn on the A/C or a space heater to provide a load during exercise runs
• Gasoline generators that sit unused develop varnish in the carburetor

Generator spark plugs and air filters need service at longer intervals than oil, but they are just as important for reliable starting and clean operation.

Spark plug: Replace every 500 hours or annually. A fouled plug causes hard starting, rough running, and poor fuel economy. Gap the new plug to manufacturer spec.

Air filter: Inspect every 6 months, replace annually or more often in dusty environments. A clogged air filter causes the generator to run rich, wasting fuel and fouling the spark plug faster.

Fuel system:

• Gasoline generators: Use fuel stabilizer if the RV will sit for more than 30 days
• Diesel generators: Fuel comes from the chassis tank. Keep the tank above 1/4 to prevent sediment pickup
• LP generators: Check regulator and fuel line connections for leaks

Most generator problems stem from infrequent use or deferred maintenance. Here are the most common issues and how to prevent them.

Generator won't start:

• Stale fuel: the number one cause. Use stabilizer or run the generator regularly
• Low oil: the low-oil shutoff prevents starting to protect the engine
• Dead starter battery: the generator draws from the chassis battery
• Tripped breaker: check the generator's built-in circuit breaker

Generator runs rough or surges:

• Dirty carburetor: clean or rebuild if fuel has sat for months
• Clogged air filter: restricts airflow and causes rich running
• Old spark plug: fouled or worn electrode

Generator shuts down under load:

• Overloaded: check total wattage of connected appliances
• Overheating: ensure adequate ventilation around the generator compartment
• Fuel starvation: check fuel pickup and lines

Water intrusion is the single most destructive force in an RV. A small crack in the roof sealant can lead to thousands of dollars in structural damage if left unaddressed.

Inspection schedule: Walk the roof every 6 months at minimum. Full-timers and those in harsh climates should inspect quarterly.

What to inspect:

• Sealant around all roof penetrations: vents, antennas, A/C units, skylights
• Seams where the roof meets the sidewalls
• Around the front and rear caps
• Any area where two materials meet

Reseal procedure: Remove old cracked or lifted sealant with a plastic scraper. Clean the surface with denatured alcohol. Apply self-leveling sealant (Dicor is the most common brand for rubber roofs). Use non-leveling sealant on vertical surfaces.

Roof types: Know your roof material: EPDM rubber, TPO, fiberglass, or aluminum. Each requires different cleaners and sealants. Using the wrong product can cause damage.

Your RV plumbing system includes fresh water, gray water, and black water tanks plus all the lines, valves, and fixtures that connect them. Keeping this system clean and functional is essential for comfortable travel.

Fresh water sanitization: Sanitize the entire system at least twice a year, at de-winterization and mid-season. Use 1/4 cup of household bleach per 15 gallons of tank capacity. Fill the system, let it sit for 12 hours, then flush thoroughly.

Water heater: Drain and flush the water heater annually. Inspect the anode rod (if equipped) and replace when more than 50% consumed. Anode rods prevent tank corrosion.

Tank maintenance:

• Use RV-specific toilet paper that dissolves quickly
• Flush black tank thoroughly after each dump. Use a built-in flush system or a backflush wand
• Clean tank sensors with a cleaning treatment if readings are inaccurate
• Keep gray tank partially full when traveling to prevent sloshing odors

Freeze prevention: If camping in temperatures below 32F, use heat tape on exposed lines, keep cabinet doors open, and consider a tank heating pad.

RV climate systems include rooftop A/C units, a propane furnace, and sometimes a heat pump. Each component needs annual service to operate safely and efficiently.

Rooftop A/C: Clean or replace the return air filter every 30 days during heavy use. Remove the A/C shroud annually and clean the evaporator and condenser coils with a coil cleaner. Inspect the gasket between the A/C unit and the roof. A deteriorated gasket causes leaks.

Furnace: Inspect the burner assembly annually before cold weather. Check for mud dauber nests in the exhaust tube. Insect nests are the most common cause of furnace failure in RVs. Clean the burner orifice and verify proper ignition.

Thermostat: Test operation in both heating and cooling modes. Replace batteries if applicable. Digital thermostats may need calibration.

Ductwork:

• Inspect flexible ductwork for kinks, disconnections, or damage
• Ensure all vents are open and unobstructed
• Seal any gaps in duct connections with foil tape
• Clean floor vents of debris and pet hair

Slide-out rooms and LP gas lines are unique to RVs. Both need regular attention to remain safe and functional.

Slide-out maintenance:

• Clean and lubricate slide rails or rack-and-pinion mechanisms every 6-12 months
• Inspect slide seals and wiper gaskets for tears or compression damage
• Check slide motor and hydraulic fluid level (hydraulic slides)
• Keep the roof area above slides clean. Debris falls inside when you retract

LP gas system:

• Test all LP connections for leaks using soapy water or an electronic gas detector
• Inspect the regulator. Replace every 10 years or if it shows signs of corrosion
• Check LP gas lines for chafing, especially where they pass through frame openings
• Verify the LP gas detector inside the coach is functional (test button) and not expired

LP safety: Never use an outdoor LP appliance inside the RV. Ensure the CO detector is operational. If you smell gas, turn off the LP supply at the tank, ventilate, and do not operate any electrical switches until the source is identified.

The chassis battery starts your engine and powers the vehicle's electrical systems. It works the same as a car battery but may be harder to access in some RV configurations.

Maintenance schedule: Test voltage and clean terminals every 3 months. A fully charged 12V battery reads 12.6-12.8V. Below 12.4V, it needs charging.

Lifespan: 3-5 years for lead-acid batteries. AGM batteries may last longer but cost more. Replace proactively if your battery is approaching the 4-year mark.

Winter storage:

• Disconnect the negative cable or use a battery disconnect switch
• Connect a smart charger/maintainer to keep the battery at full charge
• Never store a discharged battery. It will sulfate and may freeze
• Check electrolyte levels monthly on flooded lead-acid batteries

The house battery bank powers your lights, water pump, slides, and 12V appliances when you are not connected to shore power. This system takes a beating in daily use and needs regular attention.

Battery types:

• Flooded lead-acid: Cheapest but requires monthly water checks. Use only distilled water. Never overfill.
• AGM (Absorbed Glass Mat): Maintenance-free, spill-proof, and more tolerant of deep discharge. Higher cost but less hassle.
• Lithium (LiFePO4): Lightest, longest-lasting, and most efficient. Can discharge to 80-100% depth vs. 50% for lead-acid. Highest upfront cost but lowest cost per cycle.

Charging: Keep house batteries charged with a quality converter/charger when on shore power. Use a solar charge controller for solar panels. Avoid leaving batteries in a partially discharged state for extended periods.

Monitoring: Install a battery monitor (like Victron BMV) to track state of charge, voltage, and current. Voltage alone is not an accurate indicator of charge level, especially under load.

Solar panels and charging systems are increasingly common on RVs. Keeping them maintained ensures you get maximum power at camp.

Solar panels: Clean panels with water and a soft cloth every few months. Dirty panels lose 15-25% of their output. Inspect wiring connections on the roof for corrosion or looseness.

Charge controller: MPPT controllers are more efficient than PWM. Verify your controller is properly sized for your panel array. Check settings match your battery chemistry.

Converter/charger: The converter charges house batteries from shore power. Multi-stage smart chargers (bulk, absorb, float) are essential for battery longevity. Single-stage chargers overcharge and boil batteries.

Inverter:

• Keep the inverter clean and ventilated. Overheating reduces lifespan
• Check cable connections for tightness and corrosion
• Verify ground connections are secure
• Test the transfer switch operation when switching between shore and inverter power