What's the correct weight of oil I need for my 93 Unihome 8.3 Cummins?
15 40 is the right weight.
If your U280 is the same as ours (and it should be) then you can use the same Rotella T4 15W40 oil in the big engine, and in the generator engine (assuming you have a diesel generator), and in both of the hydraulic tanks. Check the tanks to be sure there is no factory sticker saying otherwise. This is nice because you only need to carry one type of spare oil for topping up everything on the coach.
Standing at the rear of the coach, peering into the engine compartment, you will be able to see two hydraulic tanks. Round, black, with a "T" handle dip stick in the lid. The tank on the left is for the hydraulic system that powers the cooling fan motors. The tank on the right is for the power steering system. They are totally separate systems, each with their own pump.
You should know the ESN (Engine Serial Number) for your engine. It is handy if you ever require engine service or want to look up parts at
Genuine Cummins Parts. See links below:
Lots of White Smoke (https://www.foreforums.com/index.php?topic=36996.msg354609#msg354609)
Genuine Cummins Parts (https://parts.cummins.com/#/)
Thanks Chuck, I'm not sure why my profile info didn't show on my post.
I changed to Rotella T5 multigrade synthetic in our 10Kw Powertech generator. Synthetic Diesel Engine Oil | Shell Rotella® T5 Synthetic Blend | Shell ROTELLA® (https://rotella.shell.com/en_us/products/full-synthetic-and-blend-oil/t5.html#iframe=L3NvcHVzL3JvdGVsbGEvbmV3c2xldHRlci9lbl91cw)
Pierce