Simplicity Onan Oil

[Beast of Busco]

I have a 16.5 HP Onan in my Simplicity 4040. It starts right up every time and runs really good, except it does burn some oil. I have used SAE 30 oil (Napa brand) in it during the summer (with a Napa gold oil filter) and used 5w30 in it last winter.

It doesn't smoke that much, and has good compression, but I suspect the rings need replaced. I have just been changing the oil more often and adding additional oil as needed (oil is cheap compared to me doing the rebuild).

With my enlightenment to the different oils on this website, I am tempted to try a better grade oil in this engine, possibly even making a blend with some of the high mileage oil. Any suggestions to spruce up this machine?

 

[416Rigby]

15w-40 is a safe bet in an air-cooled engine. Try Delo 400, or Rotella T. I'm running Redline 15w40 synthetic in an Onan 14hp on a riding mower with great success.

 

[Slick 55]

My dad's 20hp Onan has always used some oil since new. It now has 900 hours and still uses about the same amount. I ran Pennzoil SAE 30 for many years then switched to Long Life 15w40 and consumption is a tad less.

 

[DaveJ]

Way back when Onan was a Studabaker owned company they made a good power plant engine. In the "NAM" war, all the Signal Corps genorators were Onans. Where I work, all the genorators on our bucket trucks are Onans and they smoke and burn alot of oil. Verizons fleet uses only 30W but I am told in the same model Bucket truck that Qwest uses they use 15W40 and the Repair Techs I talk to dont have any smoke problems. DaveJ

 

[Beast of Busco]

Thanks for all the responses!

I probably add about 1/3 to 1/2 quart every 15 hours of use (it takes me about 2 hours to mow my 3 acres). I check the level before every use.I have noticed that after an oil change, the consumption drops for a while, then steadily increases. I change the oil in the spring, about mid-year, and then again before winter.

I think that I'll try the 15w40 and see how that works. For the winter, I'll probably stay 5w30, hopefully we won't get much snow and I won't have to plow the drive much!

 

[Beast of Busco]

I changed the oil tonight to the Shell Rotella 15w40. I added about 3-4 ounces of LC (3.5 quart sump) and changed the Napa filter. I figure I'll be mowing into October, so I have some time to see how it does before winter.