using synthetic oil in genset

[John Z]

Recently had my genset gone through. Replaced the needle valve to stop it from flooding. It runs great now, but now without all that excess gas to cool things down, it is a lot warmer in the bay with it running. Back when i was putting 15,000 miles a year on my bikes, i would switch to syn oil for the summer. I always figured it was worth about 20 degrees or so. I want to do the same with my CCK Onan. It seems to be in great shape and i think the syn oil would help keep it that way. What weight would you guys use? I am thinking 15w-50 for the summer and a lighter weight if i am going to operate it in way cooler temps. Any other ideas for cooling things down in there like running fans etc?

[Ncbob]

Onan generators of that era were NOT, repeat NOT designed for synthetic oils.  In fact when that rascal was engineered and built synthetic was a dream of the engineers.

However, it's you generator..you can certainly do as you wish.  The question in my mind is: why would you even entertain the thought?

The fact that I could indentify your generator make from the model # ought to tell you something about me and my background.  I was an Onan Dealer for almost 20 years....

FYI, Mobil 1 broke Lycoming engine company with their synthetic oil....it created and allowed rust on the camshaft lobes and Lycoming had to replace 1000's of them.

Do it your way........

NCbob

[John Z]

OK, that is the kind of info i was hoping to get from here. The fellow who went through the generator suggested the use of syn. I know it works well in the air cooled bikes i have owned. I would always put it in before a trip out to Sturgis and similar events. But i will go by your word and not make the switch. I change the oil pretty often anyway,,, i just thought if i could get the same additional 20 degrees worth of temp, it might keep things cooler in the bay. Thanks.

[justin25taylor]

I agree with Bob.
Back when we tried a few Onan's, we tried the synthetic thing without success. BTDT


I use synthetic in the Kubotas without any issues. My genset runs for months on end I only shut it down to check or change the oil. They always last many, many thousands of hours.

If you can spare the power to run it,might try to find an old blower out of a dead HVAC unit to move air in or out of the bay. Every little bit helps

Best,
Justin

[TomC]

My question is this- would you run synthetic in your Briggs and Stratton lawn mower?  The Onan two cylinder is nothing more than exactly that- a big lawn mower engine detuned to run at 1800 rpm instead of 3600 rpm.  In my opinion, the only place synthetic should be run is in the axles and transmission.  I think it is a waste in the engine since you have to change the oil periodically anyway.  The only way you can get away from changing the oil often in an engine is to have a centrifuge oil filter-of which most good ones are too large for mobile use.  No matter how long any of the filter manufacturers or those with the infamous toilet paper filter claim, you still have to do an oil analysis on the oil to see just how long you can run it before dangerous acids build up to a damaging level.  Personally, 10 gals of Delo 100 SAE40 every year isn't much as far as cost.  Good Luck, TomC

[John Z]

No i would not run syn in my lawn mower because i am not concerned with lowering the operating temp of the lawn mower engine. Also lawn mowers cost a couple hundred bucks and are pretty much a disposable item. 

[Frank @ TX]

Hi JohnZ,
Where is the heat coming from, the exhaust pipe?   The remote rad not drawing the hot air out? The engine cooling system dumping the heat into the bay?
That's the first thing to look at long before thinking about engine oil.
Frank

[DrivingMissLazy]

but now without all that excess gas to cool things down, it is a lot warmer in the bay with it running.

As a genset manufacturer for many years, I do not understand how excess gas was keeping the compartment cool and what is a lot warmer? Have you actually checked the actual bay temperature? I really do not know how changing oil would change the bay temperature and I would never consider 50# oil unless the engine is totally worn out.
Richard

[John Z]

The heat is coming from the exhaust pipes or header, since it is finally running correct instead of being loaded down with all the excess gas. It is air cooled so no radiator. And i never said i was going to use 50 weight oil - did you read the thread? The engine is in very good shape and i would like to keep it that way. Syn oil will lower the temp of the engine and i thought that could be a benefit.

[JackConrad]

When we still had our very old Onan 6.5 KW gasolene air cooled generator, I installed an oil temp gauge. We never saw the oil temp get above 160. That was standard 30W motor oil.  Ii do not know how much cooler synthetic would run.  Jack

[DrivingMissLazy]

The heat is coming from the exhaust pipes or header, since it is finally running correct instead of being loaded down with all the excess gas. It is air cooled so no radiator. And i never said i was going to use 50 weight oil - did you read the thread? The engine is in very good shape and i would like to keep it that way. Syn oil will lower the temp of the engine and i thought that could be a benefit.

I am thinking 15w-50 for the summer and a lighter weight if i am going to operate it in way cooler temps.

John, I based my reply on this statement you made. Perhaps I mis-interpreted it.
Richard

[TomCat]

The heat is coming from the exhaust pipes or header, since it is finally running correct instead of being loaded down with all the excess gas. It is air cooled so no radiator. And i never said i was going to use 50 weight oil - did you read the thread? The engine is in very good shape and i would like to keep it that way. Syn oil will lower the temp of the engine and i thought that could be a benefit.

Maybe a few layers of exhaust pipe wrap will keep the exhaust heat inside of the pipe until it's outside of your genny bay.

Jay
87 SaftLiner