What oil viscosity is your Onan using?

[Seeburg220]

Curious what viscosity others are using in their Onan's? Not interested in drivetrain viscosities, just the Onan. I'm using 30W. Also, conventional or synthetic? This doesn't have to be an oil discussion, as those tend to get out of hand. Just a simple answer of what you are using. Thanks!

 

[RF_Burns]

I'm running Amsoil Z-rod 10W-30 synthetic for classic flat tappet engines in the Onan .... same as in my 455.

 

[Matt Colie]

Mark,
I will advise that you run a good synthetic. I run Mobil 1 then same as the main engine mostly for convenience. It is not a waste of money. Little engines like that tend to beat up their lube oil as they have no lube oil cooling other than the dwell time in the pan and the synthetics make fewer corrosive products than does most dino based lube oils.
Matt_C

 

[LarryW]

Quaker State 5W30 Full Synthetic.

 

[radcaddy]

I think the Onan doesn't care at all as long as it just has OIL. Use any 30W that you want, check the level regularly and change it every now and then. The Onan is a tank and it does not need or require anything other than a good drink of oil. So run whatever you want. Just make sure it has oil. Brand A or Brand X, conventional or synthetic.

Oils well that ends well.

 

[Ken B]

One thing I have learned from working on and being around air cooled aircraft engines is you do not want to use oil that is too thin. Air cooled engines are built looser to operate at various temperatures on heavier oil. Also for this reason it is normal to burn a little oil especially in hot weather. These engines run at various temperatures because there is no thermostat to regulate temperature to something like 180 or 195. You do not want to lose lubrication when the temps get high.

You also do not want to use synthetic oil in an engine that burns some oil. I have seen one engine that was being torn down due to a cylinder failure. He had run (illegally) synthetic oil in it. Everything in all cylinders was covered with a rock hard glass like deposit that was next to impossible to remove. They ended up scrapping the cylinders, pistons, and valves on that engine.

Arch (GMCer Richard Archer) who had an oil burning problem on a newly rebuilt his 455 years ago had that same deposit issue from synthetic oil on the one cylinder that was burning the oil.

For the above at reasons I use 15W 40 Rotella non-synthetic oil In most of my air cooled engines 4 cycle engines. . For the same reasons we use non-synthetic AD Ashless Dispersant oil in airplanes . Usually 50 weight, but 65, and 40 is also available. We also preheat engines before start when the temperature gets below about 30 degrees.

 

[Carl Stouffer]

I run 30w conventional just like the manual says. But, I agree that the Onan is probably not too particular.

 

[RoadWarrior]

Curious what viscosity others are using in their Onan's? Not interested in drivetrain viscosities, just the Onan. I'm using 30W. Also, conventional or synthetic? This doesn't have to be an oil discussion, as those tend to get out of hand. Just a simple answer of what you are using. Thanks!

Shell Rotilla 20-50. Same as what I run in the motor for the zinc additives.

 

[jim miller]

John Deere torq-gard 30W. Gets good reports from the oil lab that I have look at my oil every 100 hrs.

 

[Carl Stouffer]

I've seen Briggs & Stratton oil at the hardware store. I wonder if something like that is worth the extra money. Seems to me it would be formulated for the special conditions of air cooled engines.

 

[RoadWarrior]

I've seen Briggs & Stratton oil at the hardware store. I wonder if something like that is worth the extra money. Seems to me it would be formulated for the special conditions of air cooled engines.

You might check on Corsa.org, the Corvair site. Should be a lot of articles on oil in air cooled engines and there must be a VW Bug site out there. Probably more opinions then there are drops of oil though.

 

[mike foster]

I use 15-50 Mobile-1 in everything......huge temp range, 1200 ppm ZDDP.....

 

[Ken B]

15w40 in both engines.

 

[Matt Colie]

The reason the Onan specifies single weight oils for different temperatures is just history. 50 years ago Multi-vis oils were not very good and suffered a lot of shear down in service. This situation ended about 40 years ago, but some always take a while to catch on.
Matt_C