Oil weights?

[CAROLINA CUMMINS]

First of all I use 15w-40 fully synthetic oil from Conklin. The owners manual and service manual both recomend this weight for 10 deg on up. Well before this truck was mine my grandpa run the same Conklin fully synthetic, but in 30 weight: for 10 years with no apparent ill effects. Now it comes time to order some more oil ( 15w-40) and you have to be a distibutor, which I'm not, and my grandpa is. So I hand him the money and tell him what I need, and he kinda fudges around and won't really order me any.

Saying I can use 30, which I have 4 or 5 cases of. But I really don't feel comfortable with using it. (I havn't changed it yet). I was wondering what you guys run(oil), and your comments.







Thanks, Steve

 

[Bob Beauchaine]

30wt is not now nor has it ever been recommend for your First Gen. I suspect that this came from the old Detroit Diesel 2 cycles that required a 30wt oil.



I use Amsoil 15W40 full synthetic and have for tha past 145,000 miles. The truck now has 156,000 + miles and the oil analysis from my last change looks as good as the first analysis.



Bob

 

[Midnite]

Steve, when you say 30wt, do you mean the old non-detergent straight 30wt (ie, not multi-viscosity)? If so, I'd probably agree with Bob, however what it really boils down to is if the oil has the right "C" and "S" API ratings. According to my '92 owner's manual, the minimum required API ratings are CE and SG (you need both). If it has those ratings (which I really doubt), it would actually be okay to use.



From what I've read though, old oil just sitting around in containers for years allows some of the additives to settle out. If you do use anything that's been sitting around that long it would probably be a good idea to shake or stir it up real good prior to use.



Mike

 

[JLEONARD]

I use 15-40 Rotella T. I would recommend using a modern 15-40 with the proper ratings... .

Just be advised that the rating codes keep geting superceded.

 

[Tim1]

chevron

I use chevron dello in everything except the Harley, always have and always will! This is a real touchy subject, and thats all i'll say. Tim

 

[dusthomps]

Rotella T

I've always run Rotella T in both of my trucks, but the previous owner of my 91 said he ran 10-40 during the winter months. To the best of my knowledge it had no ill effects on the motor.



Dustin

 

[CAROLINA CUMMINS]

Thanks,





All I needed to know was if 30 weight was not reccomended.









Steve

 

[Underdog]

My owners manual states" Use only high-quality Multi-Grade

lubricating oil in your Cummins Turbo Diesel Intercooled

Engine. "