10w30 vs 15w40 son

15w-40 Rotella T4 for me usually, however I have run T6 5w-40 full synthetic a few times. It is rated for my truck. Engine smells funny for a few days after a change with T6. I should probably make up my mind and not switch around but the Blackstone reports are always good so I guess it isn't hurting anything.

I have not used one or t'other long enough consecutively to see any mileage difference.

Last oil change I couldn't find either and used Lucas 15-40 non-synthetic from Rural King. It was super cheap, like $50 per 5 gallon maybe? Seems fine, truck hasn't blown up.

 

15w40 Delvac, that's what says on the engine. Rotella sometimes when Mobil is out of stock.

 

Would not think of running anything other than 15w40 in a diesel. I've known people to run 15w40 in a minivan.

 

From what I have read a higher WT oil will be better long term and better in warmer weather but if your going to trade in the trucks at 500K I don't think you will see any problems with 10-30 WT and if your going to do cold starts below 0 then a full synthetic will be of a benefit.
Hit up youtube for what different oil pours like in cold temps

 

What is the oil thing yer speakin' of there ol' son?

 

Guess you know who the one vote is now

 

It's what we use down here seeing as we don't have all that maple syrup you folks up north have.