Onan 4000 Generator Oil Type, Oil Capacity, and Oil Filter

Lubrication is key. Whenever you are dealing with motors, of any type, you will need top lubrication to make them run right. Without it, those motors can seize up and cause you a lot of expensive repairs. Picking the right oil is essential to make sure your generator has the right lubrication.

It seems that the oil you need is SAE 30 or 15W40 type of motor oil to run an Onan 4000 generator. At lower temperatures, you are allowed to use 5W30 or 10W30 motor oil. This means you have a little leeway if you cannot find the right SAE at your local stores.

To learn more about this topic, just continue to read our article, It has the information you want to know about so you can keep your Onan 4000 running like a clock. Take a couple of minutes to see how this information helps you.

What Oil Does an Onan 4000 Generator Use?


A lot will depend on the temperatures you are camping under. For those people who camp in warm weather, SAE 30 weight is good enough. For cooler temperatures, it is recommended that you use one of the following SAE types- 15W40, a 10W30, or 10W40.

Of course, if this is a diesel motor inside the generator, then you will want oil that is made for diesel engines. If it is a gas engine, then normal engine oil will suffice. Then if you are a winter camper, it is said that 5W40 is the best option for your generator.

The manual has a chart that lays it all out for you. It reads like this:

- 30W is good for 32° and higher,

- 15W-40 is good between 10° and 100°F,

- 10W-30 and 10W-40 are good between 0° and 80°F,

- 5W-30 is good between -20° and 50°F.

Onan Microquiet 4000 Oil Type


For this device, you are basically looking at the same chart of oil types as mentioned in the previous section. Some owners make their own decisions and often run 10W30 in warmer weather and they do not report any problems.

The manual should have a chart as well laying out which oil is best at which temperature range. That is what you should fol as Onan knows what it is talking about when it comes to its products. At least we hope they do.

The key is to pick the right oil type and stick with it. You may find that SAE 30 is just as good of oil as 10W40 and other options.

How Many Quarts Of Oil Does an Onan 4000 Generator Hold?


According to Cummins, who makes Onan generators, the oil capacity is 1.6 quarts of oil. You can pick up the oil you need at any local auto parts outlet. If you want the specs for this generator, they are listed below:

- 4-cycle, OHV, single horizontal cylinder

- max power at 60 hz, Gasoline – 8.3 bhp (6.2 kw)

- air cooled

- oil capacity 1.6 qt

- Cylinder Crankcase: Aluminum alloy with iron

- cylinder liner cast into the block, aluminum alloy oil base

- Cylinder Head: Aluminum, valves in head

- Fuel use: .7 Gallons per hour at full load

It is recommended that you change the oil every 100 hours of use.

Does Onan Microquiet 4000 Have An Oil Filter?


Most do not but at least one does. There are several Onan 4000 models and all but one have been designed to operate without an oil filter. The model that does have one is the Onan Genset.

If you do own an Onan that does not come with an oil filter, you may have easier maintenance duties but you will have more worries. That is because you have to watch for clogs more often.

For those without an oil filter, it becomes more important that you use the right oil for the right temperature level. There are a few more worries for those models without an oil filter.

What Oil Filter Does an Onan 4000 Generator Use?


The oil filter part number is 122-0645. You will need that number if you want to cross-reference it to buy a cheaper brand and still have the same performance.

To find out when you need to change your oil filter, check your manual. It should state when the filter change is necessary. When you do change it, do not use old oil. Change the oil at the same time so you get the best performance out of this generator.

Your local auto parts or RV parts stores should have the right filter for you to use.

How Often Should I Change The Oil in My Onan 4000 Generator?


It has been stated that you change the oil every 100 hours of use. That may not be too frequent if you do not use your generator all the time. If you do use it a lot, it is best to do frequent oil changes so that you get the best performance out of this device.

Check the temperature levels in your camping area and pick up the oil that is best for that temperature level. Sudden drops in temperatures are exceptions and not the rule. The weather will warm up quickly again and be back to normal the next day.

Some Final Words

When you want your generator working on all cylinders, then you need to make sure you use the right oil. This correct product is not just for the lubrication of the metal parts. It is also for the temperature level.

Onan generators seem to be temperature sensitive and you need a different type of oil the colder it gets in your camping area. If you have an oil filter in your generator, make sure to change that on a regular basis.

That way the motor stays protected longer and can work to its full potential.

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