When it comes to maintaining and caring for diesel-powered and gas-powered engines, the process is very different.

These differences are important, as all RVers should care for their RV’s fuel supply with safety and efficiency in mind. Lazydays RV provides fuel system and tank maintenance our RV service experts are here to answer some frequently asked questions about fuel supply care.


How large is my RV’s gas tank?

  • Class A motorhome gas tanks range in size between 80 – 150 gallons, while Class C gas tanks average 40 – 80 gallons. Class B motorhomes have an average gas tank capacity of 25 gallons.

How often should I have the engine oil changed in my gas RV?

  • Manufacturers recommend that owners have their RV’s engine oil and filters changed about every 6 months. If you typically tow while RVing, this interval may be shorter for gas RV engines. When in doubt, refer to your owner’s manual for the recommended maintenance schedule.

Will my fuel supply freeze in the winter?

  • Gasoline has a freezing point of -100°F, so most likely no. Condensation and excess water in the tank can freeze or gasoline can separate if left idle for too long in cold temperatures. It is best practice to keep your tank above a ¼ full if you will be storing or leaving your motorhome idle for long periods during the winter.

Can I keep an emergency gas supply in my motorhome?

  • Yes, but be mindful that gas can emit a strong odor and that it does evaporate. Gasoline vapor can cause a safety hazard if it leaks into the interior of your motorhome where open flames or sparks may be present. Only keep an emergency supply if you are traveling in a very remote area and make sure to use it during or before the end of your trip.


How often should I change the engine oil in my diesel RV?

  • Manufacturers recommend that RVers have their engine oil and filters changed about every 12 months. When in doubt, refer to your owner’s manual for the recommended maintenance schedule.

What are the differences between diesel and gas engines?

  • Besides fuel type, the biggest difference between diesel and gas engines is the ignition process. Gas engines compress fuel mixed with air and ignite it with sparks from spark plugs. Diesel engines first compress the air, which heats it up, and then injects fuel to create combustion. Problems with a diesel engine tend to be more complicated than a faulty spark plug or a cracked gasket and require specialized parts.

Is diesel hard to find on the road?

  • Diesel is not as prominent as standard gasoline but can be found at most gas stations. Marking gas stations along your route that carry diesel is a great way to avoid any worries about running out of fuel.
  • There are also modern solutions like phone apps that provide locations, prices, and fuel types for gas stations near you.

Do I need to add anything to my diesel fuel supply?

  • Depending on the year and model of your motorhome, yes. All newer, Class A motorhomes must have DEF or Diesel Exhaust Fluid added to their fuel supply to meet federal emissions standards. Older models do not require DEF.

Will my diesel fuel supply freeze during the winter if I store my motorhome?

  • At below freezing temperatures, diesel fuel can freeze or experience “diesel fuel gelling”. To prevent this, add an additive to your fuel supply or store your motorhome in a heated garage or structure and run the engine every few weeks. This will help stop the paraffin wax found in diesel fuel from congealing and clogging your engine’s fuel filters.