Anyone using the same oil for V10 and genset?

[chin_k]

I use 5W20 synthetic for the V10, and 15W40 for the Onan 4000. I wonder if it is a bad idea to use the same 5W20 oil on the genset? I just hate to have one more oil type laying around.... Be honest and call me a lazy idiot if you feel like it. We are all friends here.

[ASaucyBurrito]

I would not. There is a significant difference in viscosity between the Onan recommended oil types and a 5W-20. At 100C oil temps you may be 33% thinner than what they recommend. It may be fine, but I would stay on the safe side personally. Rotella is cheap.



Viscosity info from Schaeffers:

5W-20

Viscosity @ 40°C, 50.00 -55.00 cSt
Viscosity @ 100°C, 8.5 – 9.15 cSt

15W-40

Viscosity 40°C - 111.7 cSt
Viscosity 100°C - 15.51 cSt

[chin_k]

The genset do run a bit hotter, and the 5W-20 is too thin at that temperature. I do have a hard time getting Rotella T6 locally. Seems like the T4 is a more readily available, but not T6, unless I order 3 gal pack. I don't know much about the additives in the various brands and variety to know if I can get away with Rotella T4. I probably will just go call a few local places and see. If nothing work out, I can always go to the local Onan place and get the OnanMax.