Recomended oil for Onan 4KW generator

tpi wrote:
I think passenger car XW30 synthetics are a tad too light.

And I think that statement just unnecessarily confuses the issue.

I too think that you should NOT use any oil where the first number is below 10 but that does not eliminate all "passenger car synthetics".

Given the situation, an air cooled gas engine often runs when the outside temp is really high, a 10W40 or 15W40 would be preferred for most people, I think.

Onan manuals are always an interesting read. There is an Onan standby generator using our Ford V10. 15W40 oil is recommended, and 5W30 is only recommended to 50 degrees F. FWIW they also call for cylinder head rebuild at 1000 hours (or two years whatever first) on the V10. 1000 hrs. translate to 30,000 40,000 miles of typical driving? Ummm don't think I'll be pulling the heads..

To answer your question-in warmer conditions a good cheap oil is 15W40 Delo or Rotella. I use Mobil 1 0W40. I think passenger car XW30 synthetics are a tad too light. Maybe mixed 50-50 with the same brand synthetic XW40 would really get it about right-a 30 weight on heavier end of spectrum.

SAE 30 32 to 100+
15w-40 10 to 100+
10w30/40 0 to 100
5w-30 - -20 to 50

The latter numbers is the temp range... per the manual. I ran Rotella 10w30 last time around 50 hours with no issue's. I put Pennzoil Ultra 5w30 in it this time. If your using synthetic's probably any range will work but with dino juice I'd stick to the list above.

Just don't hit the start button filling it up!

Some of these generators are splash lubricated, no oil pump and if the oil is to thin there will not be enough viscosity to prevent metal on metal, use 30W or what the manufacturer specifies.

navegator

Great thanks.

Just curious - if the oil is low, or generator too hot, will it automatically shut down after running for an hour or so?

My Onan 4K recommends 30W or 10W30 but these things tend to run VERY hot so I use 10W40 synthetic.....which is the recommended oil weight for most air cooled motorcycles.