Wrong oil in Cummins?

Cub n M in OR · Dec 20, 2009

Just got back from my first winter-visit to my family cabin in the mountains. We've got a 20 year old snowcat with a B5.9 Cummins. When I started it today, it took quite some tome for the oil pressure to come up. Then it was only in the 40# range tops, and at idle would drop to 20ish. I know my uncle changed the fluids in the fall, and suspect he put 10-w30 in it instead of the 15-w40 I would have put in it. My thinking is that the wrong oil is the culprit of the low pressure. Probably was about 25 degrees today, mostly gets used in the 10 to 35 degree range.

Thanks for the help.

Ben

mike321 · Dec 20, 2009

You only need 10 psi per 1000 rpms. So if your max rpms is around 2500-3000 then 40 psi is alright.

bill mart · Dec 21, 2009

I dont know,15w40 is thicker than 10w30 and would more likely act like you are describing.Bill M.

Southtowns27 · Dec 21, 2009

I'm guessing it's a Tucker if it's got a Cummins 5.9 in it. I have a '67 Tucker 442-A. Anyway, I wouldn't be worried about your oil pressure. The 5.9 in my truck only carries about 45psi at speed.

John730D · Dec 21, 2009

Cummins says 2 PSI per cylinder is good at idle. 6 cylinder = 12 PSI.

My semi with the M11 only caries 40 PSI when warm, 20 @ idle.

Cenexguy · Dec 21, 2009

Pressure is detected by resistance to flow. The higher the pressure the higher the resistance. Be glad that the resistance to flow is lower in the cooler weather. That means that you are getting the lubrication to the most critical parts of your engine faster that you would if the pressure were to be, lets say double the pressure reading. There is a level at where the pressure becomes so low that you need to be concerned.
Keeping this in mind, some of the new cars are comming out with 0W30 oil in them. The sending unit that is designed to alert us to low oil levels are sometimes set to lower than one percent.

scot in pa · Dec 21, 2009

The 0w-xx pumps into the motor faster when it's cold.

Mike Aylward · Dec 21, 2009

Cub, I would be more worried if he used an automotive type oil rather than a diesel oil. Gasoline engine oil is not well suited to diesel service. Mike

fixerupper · Dec 21, 2009

In theory I would think the thinner oil would come up quicker when cold. The pressure drop won't happen until the engine is warmed up.Jim

Wrong oil in Cummins?

Cub n M in OR

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