Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 12, 2025 ...

Oil for gen-set?

February 17, 2017, 01:20:16 pm

Getting ready to go up to my two favorite techs in Flagstaff for a major service. I've always used the same Delo 15/40 in both engine & gen-set. My files show Onan specs 20/50 for our "Marquis. Is it a big deal to use 15/40? 

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Re: Oil for gen-set?

Reply #1 – February 17, 2017, 01:48:41 pm

Same for both, keep simple and don't worry about it 😎🌵

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Re: Oil for gen-set?

Reply #2 – February 17, 2017, 01:56:44 pm

   Mike ,
 I use  Rotella 15/40 in both the gen-pac and the 3208 it keeps it simple that way, maybe the 50# recommendation from Onan may reflect coverage for max use and abuse. Seems to me that Harley used to recommend 50# in there motors and a lot of my drag racing pals like heavier weight oils to offset high temp viscosity loss. is it because the gen is air cooled and running like the clappers .......HOT that the 50# is preferred

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Re: Oil for gen-set?

Reply #3 – February 17, 2017, 01:59:39 pm

If your gen-set is air cooled the 20/50 would be a better choice

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