Oil Type: What Oil Does my Onan Generator Use?

It's an independent life. That is what they say about life as an RV owner or user. One way to stay independent is to make sure you have your own power source. Then learning how to maintain that power source helps keep you independent and free

What Oil Does my Onan Generator Use? The best oil you can use for your new Onan generator would be a SAE 30W viscosity oil. At best you would probably need to use 1.6 quarts to fill the oil tank.

To get all the facts about maintaining your Onan generator just continue to read our article. The facts help make your Onan generator last along time.

Onan Generator Oil Recommendation (viscosity)

All the word viscosity refers to is the measure used to determine the oil’s resistance to flow. The first number refers to the oil’s resistance to flow and the second to its thickness. The lower the number the thinner the oil

A good SAE 30 W oil would do the trick for your Onan generator. The brand is not as important as the viscosity levels. You may want to check your owner’s manual to see what recommendations they make.

Onan 4000 Generator Oil Type

The type of oil you should use depends a lot on the outside temperature in the area you are running it in. For those areas that are 32 degrees F and higher, you can get away with using a 30W oil.

For lower temperatures, you can drop to a 15W40, a 10W30 or 10W40 and for extremely low temperatures, you should use a 5W30. All of these oil levels are SAE rated.

How Much Oil Does an Onan 4000 Generator Take

When it is time to do an oil change on your Onan 4000 generator, you will not need to buy a lot of oil. The generator only takes 1.6 quarts of oil. YOU can get away with buying only 2 quarts unless you need extra oil lying around your RV for other duties.

Onan 5500 Generator Oil Type

Onan recommends that you use a 10W40 oil viscosity when changing the oil in your 5500 generator. That is if the area temperatures range from very mild to hot. Also, the oil should be very diesel specific if it is a diesel powered generator. If it is a gas powered one then any oil at that level will do.

Some generator users have been able to use Mobil1 20-50 Synthetic Oil and received good results.

Onan 5500 Generator Oil Capacity

The oil tank size for this model of Onan generators is 2 quarts. That is about half the size of most modern small cars. When you do your oil change, you should not have any left over oil taking up storage space.

Does an Onan Generator Have an Oil Filter?

Most Onan 4000 don't require an oil filter. But the 4000 Genset does. When the time comes to change it, you will need a special oil filter cup wrench to get the old filter off and the new one on. As you remove the old oil filter, make sure to check to see if the gasket came off with it. If it didn’t, you will need to remove it yourself.

Here are the filters you should use Onan 122-0836, NAPA 7398, WIX 57398. Double check your owners manual to make sure your engine type does not take a different one than those listed.

The Microquiet 4000 does not come with an oil filter while other models in its class do.

Onan Generator Oil Consumption

Generators are not big on preserving oil. Depending on the year, make and model of your generator you can use up about 1 quart every 50 hours of operation.Some models will only use about 1/2 quart every 75 hours.

If the oil is too thin, then expect to burn a little more over those same time frames.

Onan Generator Oil Change Frequency (4000, 5500)

Different generator models have different oil change deadlines. Some generator users were able to go over 500 hours using synthetic oil and did not make a change. But it is recommended that for the 4000 model, you should change the oil every 100 hours or so.

For the 5500 model, that time limit is extended to 150 hours. To be exact, you should check your owners manual and see what the manufacturer says.

How to Change Onan Generator Oil

Changing the oil on an Onan generator is not the same as changing the oil on your car. There are some differences. Here are the basic steps to follow:

  • First, run the generator for a brief period of time to warm up the oil
  • Next, urn the generator off and remove the green cover over the drain plug
  • Third, use a 9/16 socket to remove the drain plug
  • Then, let the oil drain into an oil pan. If your generator has an oil filter,yo need to remove it at this time and replace it with a new one
  • Once the oil is out, put a little sealant on the plug and screw it back in.Just do not over tighten it
  • Finally, remove the oil cover and replace the oil. Check to see that you do not over fill the oil tank

Onan Generator Oil Smells Like Gas

One possible origin of this problem is that gas has gotten into the oil somehow. When this happens it could be that you have a carburetor problem. The carburetor is probably plugged by varnish.

When gas ages, it tends to turn into varnish and will clog up the lines in the carburetor blocking the newer gas from getting through. When gas sits for a while this process starts and using fuel additives will only slow it down

Some Final Comments

Having a generator with you when you use your RV is a great idea. They help save your batteries, keep you powered up and can take the load off when you do not have any electrical plug-ins.

Maintaining your Onan generator is important and as you can see, there is not that much to maintaining your model. The oil changes go quickly and all you need to do is learn which oil to use in which temperature zone.

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