What Weight Oil Do You Run In Your Generators ?

I just changed the oil in my pressure washer this morning. (Kohler 6-1/2 H.P.) It just about polished off the 5 quart jug of 15W-50 Mobil 1, I had bought. So I was able to get the oil changed in both Westinghouse 9,500 watt gen sets. My little Honda EM-600, and the pressure washer out of 1 jug.

The next time I go to Wal-Mart I'll look for another to have in stock. That's getting to be a real problem. My Wal-Mart automotive section is HORRIBLE as far as keeping oil in stock. They are constantly out of Pennzoil 5W-20 Platinum Full Synthetic. Along with several other popular weights and brands. Is anyone else finding this as well? It seems about the only thing they have plenty of are the, "High Mileage" oils.

I just Googled "Why is Wal-Mart out of stock on so many items?", and I got the phone book. It seems it's a common problem lately.
 
I run 5w-40 Rotella T6 in all of my outdoor equipment including my Yamaha 4 wheelers.
22 HP Briggs in my riding mower, 30 HP in my Generac 15000 Watt generator, Champion 6250 Watt inverter generator, Kohler 6 1/2 HP (never change oil) push mower, log splitter, and Honda powered pressure washer.
I use Synthetic Mobil One 0w-30 in my snow blower though.
 
Thanks.

Do you have any evidence that you have a shearing issue now to be concerned about?
Gensets aren't typically quad cam high specific output DOCH utilizing feet of timing chains that shear oil heavily.

Often times narrowing the spread ends up degrading the base oil, with the highest base oil level being the "0W" variant.
Are you sure that isn't the case in your choice?

Id be interested to see if you ran some UOA's
I ran some on my Onan 8000 running off the shelf 0W-40 and it was fantastic showing I could go for far longer than the recommended 150 hours, holding up just fin e in an oil known for shearing.

Neither my 20KW Kohler, or any other gensets recommend increasing the W rating in hot temps.
There are plenty of posts here from our friends down in Florida regarding the use of 15w-40 in generators. I think that Cujet has a lot to say on this.

As I said earlier, I run 5w-40 RT6 in my generators now. They might be called upon to run anywhere from zero to 100 degrees F. I would not hesitate to use 15w-40 if running for multiple days straight in 90 degree weather.
 
I use 15w-40 HDEO in my generator, I recommend using robust oil in an engine that runs continuously and you rely on to keep the power on.
The lawn mower gets the left over scraps of oil, but that's not keeping the lights on and only runs for ~45 minutes at a time.
 
I think 15w40 is great for generators, unless they are recoil start in temps under 30f. Pull the cord on 15w40 in 20 f weather and the whole generator will come off the ground.
 
15w - 40 oils are better oils than 5W-40 oils.

Is that universally true?

Better in what way, sometimes the base stock gets better, sometimes it seems to get worse. Add pack?

I get that it probably has a higher HTHS number - but how much higher?

IF you are going to address a hot running condition by upping the W number - why not narrow the spread further by going to 20w-40?
 
Is that universally true?

Better in what way, sometimes the base stock gets better, sometimes it seems to get worse. Add pack?

I get that it probably has a higher HTHS number - but how much higher?

IF you are going to address a hot running condition by upping the W number - why not narrow the spread further by going to 20w-40?
Does Walmart sell 20W-40?
 
Does Walmart sell 20W-40?

Never looked for it- couldnt tell you.

to the OP - I had a house in parker for 15 years, Im sure you know but for the posters here its the same place, the parker dam makes lake Havasu, and Ive never lived in a hotter part of the world.

I saw trees chasing dogs, and 120 in the shade many time,
something W50 will be fine for summer, and I wouldnt run anything lower than X 40 in the summer there in an air cooled genset for any length of time.

Id recommend a basic sunshade over a penny in havasu - like this pict.


I rigged up a mister for mine to keep the intake charge cooler.

Interesting avatar - looks fun whatever they are.

IMG_2077.jpeg
 
Last edited:
I stopped at Auto Zone today to get some oil for the generator . I saw some STP Full Synthetic 10w-30 motor oil . I wasn't aware they marketed an oil . For $5 and some change / qt. I'll give it a try .
 
Back
Top