Oil change intervals - are we all following the manufacturer or going by feel?

I've been turning wrenches on diesel trucks for about 12 years now, and I keep seeing guys at the shop argue about oil change intervals like it's a religion. On one side you got the sticklers who say follow the OEM manual to the letter, like 15,000 miles on synthetic or whatever the book says. Then you got the old school guys who swear by 5,000 miles no matter what, even with modern oils and filtration. I had a customer last week with a 2019 Cummins who was dead set on 3,000 mile changes, and I tried to explain he's wasting money and oil, but he wouldn't budge. But I also had a guy with a 2015 Duramax run 20,000 miles on the same Rotella T6 and his oil analysis came back clean. So which side are you on? Do you trust the engineering or go with the 'better safe than sorry' mindset, and have you ever seen an engine fail from stretching it too far?

2 comments

2 Comments

patriciareed19d agoMost Upvoted

I had a buddy who ran a fleet of box trucks and he switched to 20k mile intervals on synthetic after doing oil analysis for a year straight. No failures in over 300k miles on those engines. The thing is, most guys don't realize how far oil technology has come since the 90s. But I get the hesitation if you're towing heavy or idling a lot that changes things a bit. For daily driving though, 15k on modern synthetic is probably fine for most modern diesels. Still makes me nervous honestly but the data backs it up.

dianal9419d ago

Man, oil analysis is the only way to really know for sure what your engine needs.