Now, Cummins recommends 15-40 API grade CI-4/SL.
What would be the best motor oil (brand), is there any specific oil to avoid?
I live in a rather cold climate now, 30's to 40's in temperature, if that's an issue.

 

5-40 is fine to run in these engines for cold climate. Delo 400, rotella, or amsoil are going to be the best.

 

i've worked in a shop for a very long time in minnesota where temps get as low as -40 degrees, and i've never put 5-40 in any kind of diesel, it's way too thin even if the temps are below zero. I have personally owned diesels for a long time as well, started with a 6.5 TD chevy 1/2 ton and worked my way up to my current cummins and would never even consider using 5-40 in it. We had an oil tech come to our shop to do some research and he told us to stray away from using rotella anymore because they aren't current with their additives in their oil...he recommended Valvoline Premium Blue 15W-40 for any diesel motor, and best of all, it's recommended by cummins inc. now and cummins certified! I just changed my oil today, after running rotella all my life in my diesels, i have now converted to Valvoline. I grew up in a truck driving family and we swore by rotella...not no more!

 

Thanks.
Can I get Valvoline at all gas stations?

 

i'm not really sure, i just called the local parts store and they had three gallons of it so i told them to send it over...to be honest with you, i've never even looked at a gas station, but i'm assuming that they would have it at most truck stops and bigger gas stations

 

Charles D.

What year truck do you have? Please fill in your sig file so we all know what you have. This also helps if or when you have a problem and need help everyone will know how to help based on your year of truck.

 

Cummins and even Dodge has said that its OK to use 5w40 oil (at least in the 2006 engine) as long as it is Synthetic oil (you can not use 5w40 Synthetic Blend) and its ok to used it year round. I have talked to several people who live in CA and have no problems with using Amsoil 5w30 HDD oil. In fact I have it in mine right now and the engine has less noise at all speeds even idle then it did with 5w40 synthetic Rotella in it.

BTW, in my owners manual it recomends you to use 5w40 synthetic oil any time the temps get at or below Zero degrees between oil changes. My self I changed my oil when I think the temps would stay at or below 10 above zero for more then one or two nights at a time with it parked in my garage.

 

Thanks for the tip DBLR,
Let's now see if my signature shows...

 

Cummins recommends conventional oil changed more frequently in their engines....but recommends synthetic gear oils in transmissions.

http://www.cummins.com/na/pdf/en/pro..._Whitepape.pdf

 

Hank,

Do you have any recent information from Cummins that is for our 5.9L engine and not the 2003 semi engine PDF you posted?

I feel by using quality synthetic fluids in my truck, I not only get a gain of 1+ mpg, I also get a engine that will last a lot longer then the body around it. Of coursedid you forget that Cummins endorses Valvoline Blue Extreme that is printed on the label Synthetic oil?