15/40 oil for propane generator

[RalphVa]

I use 5w30 M1 in my lawn mower engines. Should be fine for your Onan air cooled. Think the only difference between diesel and gasoline engine oils is extra detergent to keep the soot in suspension on diesel oils. Diesel oils can be used in gasoline engines, if the 15/40 is what is speced and still under warranty, just use what you use in your tractors and then when off warranty, switch them all to 5w30. That's what VW had speced for use in its diesels for many years. Castrol 5w30 from VW is what I use in my JD and Isuzu diesel engines here in Va. Plan to switch to 0w30 M1 ESP when I'm out of the Castrol stuff because I'm an Exxon Mobil guy who worked in lube oil industry for 31 years and know that M1 was always the best. (Never saw any tests on the Group V stuff that's out there now. Bet it's just as good. Don't think it was there much when I was working, pre 1998.)

Ralph

 

[Texasmark]

I have been using Rot T6 5W-40 full syn in my ll kW Generac since new in 2014, and my two Bransons since new. No reason not to! The lower the first number the better low temp viscosity which helps to prevent "dry" startups....like my weekly 15 minute automatic cycling to keep things in working order. Most oil charts on newer equipment now list syn multigrades and the temps along with dino HD and regular single grade and their recommended temp ranges of operation. Mobil 1 0W-xyz states on the container that it meets or exceeds all mfgrs specks for 5 and 10w-30. What gets me is I have a lot of DR equip made up in Vermont,or sold from there. The maintenance package oil that they sell is labeled DR and is 30W HD. I can't believe in today's world they sell that viscosity especially in Northern climates.

 

[nyone]

Considering DR power equipment is in business with generac i would have to say they stste 30w oil because thats what the chinese wrote in the manual.

 

[Texasmark]

I run Mobil 1 0w-30 in my 11 kw Generac purchased new in Feb. 2014. Same oil that goes in my 2011 Silverado P/U. Exceeds owners manual recommendations.

 

[Copperhead]

On my Detroit 60, I use a Schaeffer syn blend 15w40 CK4 in the summer and Schaeffer syn blend 10w30 CK4 in the winter. Just changed oil. 1,038,811 miles and 22,496 hours on the engine. Still only uses about 1 qt per 11-12,000 miles. Engine all original except the water pump. Operates from 100F+ to -25F. While synthetics are great in niche applications, I am not convinced that they really are a value and offer any longer engine life for the average user. I also use Schaeffer 5w30 syn blend (gas version) in my pickup truck and SUV and other stuff including lawn mower, gator, generators, etc. I do use a Pennzoil conventional 10w30 in the wife's 2006 Cadillac CTS 3.6. Again, all original engine. Nothing wrong with a full synthetic, but given the quality of all base oils today, the luster of synthetic has grown a little dim. Except for special applications, not worth the money.

 

[jgedmond]

My Cummins / Onan whole house propane generator recommends 5W30 full synthetic.

 

[Texasmark]

Considering DR power equipment is in business with generac i would have to say they stste 30w oil because thats what the chinese wrote in the manual.

It was there back in 2005 at least, who knows how long before that, when I bought my 52" Pro Z lawn mower from them, first of numerous purchases and still the same oil in the kits.....back when they had BS engines made in the USA on their equipment.....last piece I bought was an updated leaf vac and the engine was of their own namesake and it looked like it was of Chinese origin......but the two engines I have from there are fine, well designed, built, owner friendly machines having amenities not available on most BS engines of the same size.....per the horses in my stable.

 

[daugen]

I have the same DR leaf vac, one with largest motor on it, definitely a top quality Chonda, and the black paint job on that engine looked about a quarter inch thick.
Still looks like new three years later, granted it's one of my lowest hour per year motors. Engine always starts immediately, but very noisy clattery muffler.
and I remember the requirement for straight 30W, which I had plenty of in the barn. Now running my normal 10W-30 full synthetic in it. My normal process has been change the oil at 5 to 10 hours, use conventional oil as spec'd back in it, and following year at oil change time switch to full synthetic or part synthetic. I use semi-syn in the tractors and full syn in just about everything else.

Perhaps the chemistry has changed, but for a long time they said full synthetic was too slippery to have rings set in properly or quickly. That may be all baloney now, even base oils are greatly improved as noted above. And more and more cars/trucks come with full synthetic as oem, which I 'm sure has most to do with fuel economy.

During warranty I toe the line, and therefore bought a couple of quarts of the Onan labeled 15/40 oil. Had to hunt around to find it at a reasonable price, still expensive, must be the fancy label...

The 3.6kw gen in my rv is a 3600 rpm buzzbomb. Worse it starts up and goes full speed immediately, no warm up period.
No oil filter either, this is basically a lawn mower engine, and that's the way I'll treat it.
Being propane fired, I don't expect the plug to foul or have carburetor issues, so should be reliable like my whole house gen.

appreciate all the comments and feedback. I simply had never seen 15/40 conventional oil with gas engine ratings.
Makes one wonder why Onan/Cummins goes to all the trouble of having someone custom blend it for them.
Part of this was my curiosity, what do they know I don't?...

 

[Texasmark]

Considering DR power equipment is in business with generac i would have to say they stste 30w oil because thats what the chinese wrote in the manual.

They had it in the manuals back in 2005, my first purchase. I think the Generac purchase was a couple of years ago when things really changed in the marketing department and products offered.

 

[Rebeldad1]

I am 79 years old, and have used just about every type/brand oil known to man.
I too, have not replaced any engines yet.
Could I have done even better with Amsoil ??

Maybe... maybe not. I went with AMSoil because it was the best that I could find. I serviced several hundred customer cars with AMSoil and felt very comfortable with the decision. It was the only synthetic oil at the time that listed a 100% guarantee that if a engine failed because of their oil they would replace it. Also the only synthetic oil where you could phone directly to the lab that makes the oil to ask questions. Big plus for me.