How to Fill Up Fluids in Your RV

There are a surprising number of fluids in an RV. Whether it’s filling the gas tank or winterizing your plumbing, knowing how to properly fill and empty these fluids is super important. In fact, keeping your fluids at the proper levels is actually one of the most crucial parts of the care and keeping of an RV.

If you are just jumping into the world of RVing, you may be wondering how in the world you’re going to learn everything you need to know. Well, you’ve come to the right place. After reading this article, you’ll know all of the most important things about the fluids in your RV.

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Filling Your RV Gas Tank

Let’s start by discussing your RV gas tank. Considering you have to fill this up to get anywhere, it seems like a logical place to begin.

Fortunately, filling an RV gas tank really isn’t all that different from filling a car gas tank. Some things you’ll want to keep in mind are:

  • Diesel or regular? — Many motorhomes use diesel fuel. Obviously, you will need to know which type your vehicle takes and remember to only fill with the correct fuel.
  • Watch for low clearances — Many gas stations have coverings over their pumps. Getting air conditioner units caught on low coverings is not unheard of, so be sure to watch for this.
  • If your tank won’t fill completely — Often this is because of foamy diesel. If this is the case for you, wait a few seconds for the foam to die down and finish filling very slowly. Still no luck? Try jacking up the back end to encourage all fuel to move to the RV fuel tank.
  • Don’t run out — Keep some extra fuel on hand in sealed fuel containers. This can be a serious lifesaver when you find yourself in the middle of nowhere with an empty gas tank.

Protecting Your RV Plumbing

Besides gas, your RV will also play host to plenty of water. After all, everybody needs to shower, use the restroom, and wash their hands.

Of course, when using your RV plumbing, you will want to ensure you’re doing so correctly in order to protect the often less-than-sturdy parts. Fortunately, this is also pretty straightforward:

  • Use a pressure regulator — Using a pressure regulator every time you hook up to city water will help protect your water lines from too much water pressure.
  • Use a filter — A water filter is also a good idea. This helps keep contaminants out of your pipes.
  • Don’t run the pump dry — Make sure you have water in your fresh tank when running the pump. Running a pump dry will ruin it.
  • Winterize yearly — Always make sure your rig is winterized before the first freeze hits. Failing to do so could result in burst lines and cracked tanks.

How to Winterize RV

Not sure how to winterize your RV? It’s actually not as difficult as you might imagine:

  1. Begin by emptying your rig of all water. Empty and clean the holding tanks and the hot water tank, and use the low-point drains to ensure nothing is left in the pipes.
  2. Bypass the water heater by flipping the bypass valves. If your rig doesn’t have these already installed, you can purchase an aftermarket kit and install them yourself.
  3. Fill the lines with RV antifreeze using the water pump. Simply place the end of the provided hose into a bottle of RV-specific plumbing antifreeze and turn the pump on. Run the faucet nearest the pump until it runs pink. Turn that faucet off and repeat with the next nearest faucet until all have been run, replacing the antifreeze bottle as needed. Don’t forget the outdoor shower and the toilet!
  4. Pour a cup or two of RV antifreeze down the toilet and down one sink drain to keep the tanks from freezing.

These simple steps will have your RV ready to take on even the coldest of winters.

RV Maintenance — Other Fluids to Watch

Wondering what other fluid levels you should be keeping an eye on? Here are some of the most important ones:


In most RVs, propane is necessary. This is the fuel that runs the furnace, the stove, the oven, and sometimes even the water heater and fridge. For this reason, running out of propane can be a bad thing. Avoid this by always keeping at least one full tank on hand. Tanks can be filled at a number of places including campgrounds and some hardware stores.

Fluids Under the Hood

If you own a motorhome, there are some under-the-hood fluids you should check occasionally. These include the RV coolant, oil, power steering, and transmission fluid. You may also want to top off your window washer fluid from time to time.

RV Hydraulic Fluid

Hydraulic fluid is necessary when you have motorized slides or a motorized leveling system. Read your manufacturer’s instructions to ensure you use the correct fluid and fill it to the proper level. Some people may also find this video helpful for learning how to add fluid to their hydraulic jack system.

RV Brake Fluid

Your brake fluid should be replaced every two years. Luckily, replacing brake fluid is a fairly simple process that most handy people can do on their own. This video may be helpful for those trying to learn. Don’t feel comfortable replacing your brake fluid? Take it to the shop! This is an important bit of maintenance, and skipping it could have dire consequences.

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