Community Forums

Mason Dixon · 05-15-2016, 01:07 PM

Today I changed the oil & filter in my Onan Genny. The manual says it should hold 3qts of oil with filter change. I first added the 3qts and ran the unit for a few minutes to fill the filter. I let it sit for a couple minutes and checked the dipstick which showed add 1qt. I added another qt of oil so it took 4qts to fill the sump.

Has anyone else found this to be the case on their units?

lowejug · 05-15-2016, 03:47 PM

I have changed the oil in a 8k a couple times. From my recollection it was 3 quarts total. Even with changing the filter.
4 quarts seems high. It's worse to run overfilled they say then even u dear filled... Go to the manual and all else fails call Cummins
Best of luck

RSteele · 05-15-2016, 09:12 PM

Per the owners manual the lube capacity is 2.8 quarts. Was the generator level when you checked it? That can throw it off.

Dutch Star Don · 05-15-2016, 10:30 PM

I've had two Onan 8K generators over the last 12 years and I do all of my own servicing. The Onan 8K only hold 3 quarts. You need to drain a quart back out. Don't forget, the dipstick needs to be screwed/pushed all the down and then back out to check the oil.

johnnyreno · 05-15-2016, 10:35 PM

you may want to change the fuel filter too very easy to do there is also a spark arrestor that needs to be emptied

YC1 · 05-16-2016, 06:05 AM

Quote:

Originally Posted by johnnyreno

you may want to change the fuel filter too very easy to do there is also a spark arrestor that needs to be emptied

Ditto on the fuel filter. Not cheap but they plug and cause all kinds of symptoms.

Yes that is too much oil. As suggested. Insert the dip stick all the way.

dons2346 · 05-16-2016, 09:22 AM

Talking about dip sticks. The plastic end can and will break off. Best to replace the stick with an all metal one.

RSteele · 05-16-2016, 09:24 AM

If you are going to change the fuel filter do yourself a favor and buy the correct wrenches if you don't already have them. They are called flare nut wrenches, they will make life a lot easier in the tight space where the filters are mounted. I bought mine at harbor freight for around $10. The plug in the exhaust system is not easy to get to. You need a long extension and a flashlight. I also use a shallow socket to get the plug back in, you want some threads showing outside the socket in order to get the plug back in. Be careful not to cross thread the plug and use anti seize paste when re installing it. Never had much soot come out but I pull the plug and start the generator every year when I change the oil.

steve11669 · 05-16-2016, 09:26 AM

My 7.5 diesel manual says 3 qts and that's what it took to bring it up to the full line.

WDW · 05-16-2016, 09:37 AM

Do you use synthetic oil?

2016 Coachmen Mirada 35 BH
2015 Jeep Roadmaster AT. tow bar with RVI2 supplemental.

Taking in the sight wherever our Trolley takes us...

Mason Dixon · 05-16-2016, 08:00 PM

Well I checked the dipstick to make sure it was inserted completely, it was. The level now shows overfull so I have drained it down to mid-range on the indicator. I'm not sure why it was off but okay now. The MH was sitting level so I guess that was not the issue.
Thank you for all the replies, it's good to have so many folks willing to share their experience.

Gary RVRoamer · 05-17-2016, 10:03 AM

Quote:

you may want to change the fuel filter too very easy to do

Your Onan must be a heck of lot different than mine, cause the fuel filter on my QD7500 is a royal pain to change. Even with the proper wrenches. It's tucked up in a little cubby hole and little slack in the metal fuel tubes to get it aligned right for reinstall. When my hands are in the cubby hole I can't see anything, and fuel runs down my arm all the time I'm trying to get it hooked back up. Of all my filters, coach & cars, it's the one I most dread changing. So much that I avoid it and change only when really needed.

fly_1 · 05-17-2016, 11:22 AM

This is a link to THE RV GEEKS page on generator service. It has some nice tips for all aspects of the job.

Koop · 05-17-2016, 06:45 PM

Quote:

Originally Posted by Gary RVRoamer

Your Onan must be a heck of lot different than mine, cause the fuel filter on my QD7500 is a royal pain to change. Even with the proper wrenches. It's tucked up in a little cubby hole and little slack in the metal fuel tubes to get it aligned right for reinstall. When my hands are in the cubby hole I can't see anything, and fuel runs down my arm all the time I'm trying to get it hooked back up. Of all my filters, coach & cars, it's the one I most dread changing. So much that I avoid it and change only when really needed.

I won't change mine again. Last time I brought the replacement fuel filter with me to Speedco when I had the engine oil and filter changed. They changed the generator fuel filter at the same time with no added service charge.

That's what I'll do from now on, no more fuel running down my arm.