I was putting in a road today with the 2U D8 and noticed the L/O pressure was down to 15psi. Temp was fine. I have not run the cat for seven years and it did just fine knocking down trees and making road. I am wondering what would be the best oil to use, 40 wt Delo? Or is there a better oil for an old cat. Thanks for any suggestions.

Make sure your oil isn’t getting diluted with diesel! If it’s not that, it is probably OK. It takes very little oil pressure to keep the original CAT gauge in the operating range. The old engines had relatively large bearing areas and allowances for not so tight clearances, so they depended on high oil flow more than high pressure.

If you want to use single weight oils, you need to pick one to fit your operating environment. I think 40 weight would be fine in warm to hot weather. 30 wt for most places in North America pretty much year round, and 10 or 20 for extreme cold.

On the other hand, I like multi weight oils. I think the newest formulations are really good today. I’ve been using Delo or Rotella 15W40.

i'll repeat what CCj said....make sure your engine oil is not being diluted with diesel....

-making oil in the engine crankcase is a big RED FLAG !!

-you don't mention what weight oil you are currently using?

-i like the multi-weight oils as well:biggrin1:

I will stick with 30w. Multi grade oils do not reach full viscosity until over 200 degrees, they default to the lighter number. I want to lubricate my engines with oil not polymers.

I use 30w in all my machnes

when I was working and running some of the now vintage Cats the mechanics only had 2 oils on the truck 10wt and 30wt

Thanks for all the fine responses. I have been using the 40 wt Delo in the 2U. Run 15-40 Delo in most other modern diesel engines. Shell Rotella 30 wt. in the 19A I didn't smell any fuel when I drained the oil, I will taste it to see if there is fuel dilution. This forum is awesome with awesome folks.

I’ve always heard that you can drip some of the oil on a paper towel and see a clear/wet ring around the black spot when it has fuel in it. Not sure how accurate that is. An oil sample test would settle it for sure, but a trend over time is best with those.

Usually when the old tractors put fuel in the oil it’s not a little bit, it’s a lot and it’s a sudden thing.

2U = old = sitting long time, could be restricted/sludged up screen.

I checked for f/o dilution. nun. Replaced filters and 40wt Delo. Should be good to sit again. Thanks all.