10w30 vs 15w40 son

Funny, I had this conversation with a guy earlier today, Ive ALWAYS used Rotella 15w-40..... didnt know if it was safe to use anything else. Ive thought about going synthetic, but didnt understand the t6 vs t5 or whatever rosella has.

Edit to add---- this is for my current and former S60 12.7's

And a 14L 60 series.

 

Truck- I went from 10w30 xle to 15w40 Delo xle. Advice from a Cummins engineer. Engine sounded better after switching. Noticed very small difference in economy. X15 performance
Reefer- 10w30 delvac. For the cold starts and what my Reefer folks recommend. Never switched. Carrier

 

I run/buy from a local distributor there house blend which consist of 15/40 synthetic blend. I use it on my former Cat when it started to show more blow by and a slight consumption. I learned that Chevron Delo had changed there formula to meet newer emissions. Delo is all I’ve ever ran in the trucks I’ve owned. Long story short…. I switched to the local house blend and after 2/3 oil changes, the oil consumption stop. Even on my newer Commiefornia Comapart engine, it stopped the oil consumption. @staceydude has been using Delvac on my former Cat and has had goodluck with it. This comment is base on actual facts that I’ve experienced with my engines.

Edit: forgot to mentioned the house blend from the local distributor is half the cost of ALL the name brands out in the market. My advice, find your local distributor and ask what they have to offer.

 

Always 15-40 delvac. Cummins 2350

 

Xle 10w30 was factory fill. I bothered an engineer to tell me which one is better. He said Cummins is recommending 10w30 valvoline. I asked him if he owned my truck which oil he would use. Without hesitation he said 15w40.

 

Cummins reccommends valvoline because the 2 companies have been doing business together for along time. they have a contractural obligation to market each others products.