1982 onan 4.0 genset -Synthetic Or hdeo ?

[leroyd92]

I drained the black 30 wt ( assuming) and refiled with supertech 15w40.

Since this is air cooled, should i stay with. 15w40 or go to a full synthetic 10w30 ?

I'm in az,i do personally see us running the generator in 80-100 ° weather and also cold ( 30° is coldest for us )

 

[AMC]

I would stick with HDEO, whether synthetic or not. If you look at the additive package, volatility and TBN of HDEO compared to any PCMO; HDEO pretty much blows everything else away, especially with the additives.

For your machine and climate, I would recommend an HDEO 10w-30. Wal-Mart carries Rotella and Delo HDEO 10w-30 for a good price. That should cover your temp range and give good protection. Synthetic 5w-40 HDEO would work very well also. 15w-40 might start off a bit thick for a machine that doesn't get a lot of use and the temp can get to 30F degrees.

 

[Linctex]

I'd stick with 15W-40

Is this Onan 1800 RPM or 3600 RPM?

If it's 3600 RPM, it will last forever.
If it's 1800 RPM, it will last forever & ever & ever & ever & ever.....

 

[FlyNavyP3]

I think you're right on the money with the ST 15w40 you already have installed in the engine. Robust add pack at a value price. I wouldn't change a thing.

 

[bubbatime]

15W40 minimum
20W50 for any long stretches of use (several days of use)
Absolutely no xW30 weight oils

Originally Posted By: AMC
For your machine and climate, I would recommend an HDEO 10w-30.


No. The guy lives in Arizona. 15W40 minimum for his engine/climate. The SuperTech 15W40 he chose is a great choice.

 

[pkunk]

15-40 is the lube recommended by Onan. I use 15-40 in mine anywhere from S. AZ to the mtns of NM where I live and never had a problem.

 

[AMC]

Originally Posted By: pkunk
15-40 is the lube recommended by Onan. I use 15-40 in mine anywhere from S. AZ to the mtns of NM where I live and never had a problem.


I was assuming 10w-30 was the factory recommended weight and 15w-40 was just everyone's suggestion to go a little thicker because it is an old engine.

I will stick with the first part of my post though, HDEO is the way to go. 10w-40 PCMO is going to have a lot less additives.