The OP rig looks pretty new. Why would there be no oil filter for the Onan? My 1988 Onan 4k had one.
Our Onan 4000 had no oil filter, out Onan 5500 had one. The suggested interval for both was 150 hours and that is what I follow.
The service manual says to use API class SJ, SH, or SG with 30 weight prefered if the temperatures are consistently above freezing. The multi-weight types are recommended for when the temperature range includes numbers lower than 32 degrees F.
I always use 30 wt. because we live in FL.
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TeamFoxy ~ Traveling North America
2016 Newmar Canyon Star 3710
2017 Chevy Equinox in tow.
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I have an older Qnan Marquis 5000 in my new to me MH. I changed the oil in it to Mobil 1 5W30 high mileage, because that is what I use in my cars and had it on hand. After some checking I am going to change to Mobil 1 V-Twin motorcycle 20W50 at the next oil change, because it is designed for air cooled engines and I use the generator the most when it is hot.
We have a 5,500-watt, air cooled, Cummins Onan Marquis Gold gas generator and yes I use Royal Purple straight 30W syn because of the terrain we're normally in. If we we're in a different climate than we normally are in a lot, I'd use a different weight per manual. Royal Purple is very hard to find in any stores—especially straight 30W—so I order it off Amazon. Ours takes 2 qts. with oil filter. Just did my 100 hour change and filter last week. I change oil and filter annually. We have 1,150 hrs. on ours.
Good oil and regular changes is the cheapest mechanic you'll ever hire.
Well, it depends. Here's a screen grab from my manual.
FWIW, I do use Amsoil 10w30 small engine oil in my gasoline generator. It's really not much more expensive than any other good oil. I do change it once a year, though.
I live in Arizona and use 20w-50 in my old '99 Onan 5k. Many lighter oils will not meet the high temperature demands I need when boondocking at local lakes.
Temperatures can easily be over 100 degrees in late March or early April.
When I was working for Phoenix we were trying to find a weight oil that would meet the warranty requirements of the light duty vehicles. We found the Chrysler at the time wanted 10w-30w for temps over 100 degrees so we had to stock 2 weights of oil.
Being an aircooled engine I use full syn in my Onan genny. I choose Rotella t6 5w40. Syn oil does not beeak down under heat like dino oil so it doesnt have to be thicker to start. Search every oil test ever run and you will never find a dino oil outperforming a full synthetic oil anyplace. For a few dollars more, why take the chance....ever price out a replacement genny?
Sure, synthetic oil is better, but is it better then the engine needs ?
Big, hard working, industrial diesel engines run dyno oil. Intake air dirt ingestion or severe overheating due to a failure in the cooling system, wheather air or liquid cooled, is the killer of engines, oil can't stop that.
Quote:
Originally Posted by airshot
Being an aircooled engine I use full syn in my Onan genny. I choose Rotella t6 5w40. Syn oil does not beeak down under heat like dino oil so it doesnt have to be thicker to start. Search every oil test ever run and you will never find a dino oil outperforming a full synthetic oil anyplace. For a few dollars more, why take the chance....ever price out a replacement genny?
With conventional in hot weather it would often die when pulling off the highway, say into a campground. I attributed it to heat and less air flow. Since changing to Rotella blend it has never done that. It has been 3-4 years on Rotella.
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Shell Bleiweiss
2014 1/2 Thor Challenger 37KT
Sedona, AZ
With conventional in hot weather it would often die when pulling off the highway, say into a campground. I attributed it to heat and less air flow. Since changing to Rotella blend it has never done that. It has been 3-4 years on Rotella.
Kind of a leap to connect the two but OK.
The synthetic oil doesn't cool the engine more, it can stand more heat.
The synthetic oil doesn't cool the engine more, it can stand more heat.
Hmmm....
We have checked two Goldwing motorcycle rear drive units with a laser thermometer. One was running a synthetic gear lube, and the other was running a conventional lube. Both were running the same viscosity; both had just made the same trip under the same conditions. The one with the synthetic was, indeed, running quite a bit cooler. How that'd relate to an air cooled engine would be debatable.
My generator is not due for an oil change for several months, or I'd give it a try.