The truth about synthetic oils?

[Old_Me]

I use Delvac 1300 in everything and change oil and filter every 4000 miles. i even use it in lawnmowers. lol

nearly every trucking company i worked for told me to use Shell Rotella, no matter the diesel engine they had.

i cannot recall ever using Delvac over the years.

most times, the trucking companies followed the factory book on what oils to use.

owner-operators used whatever then wanted.

 

[OldGrunt]

Years ago, I used to have a Ram 3500 with the old 5.9 Cummins in it. One year my ex-wife gave me a gift of a 4 or 5 pack of a Blackstone Laboratories Oil Analysis kit. The factory oil change interval on that truck was between 5000-7500 miles. Whenever I received the results of those oil samples back, it always said I could safely do another 10,000 miles before needing to change the oil. I bumped up my oil change intervals to 15,000 but was a little too worried to chance it further. I never had a bad test result, and I traded that truck in on my current one at over 275,000 miles. My current 2020 6.7 Cummins has 15,000 for an oil change interval. And that's what I do that one at. I don't sample my oil anymore. But I do run Schaffer's 9000 full synthetic in it. For those that don't know, that is a very good oil.