Vent: The difference in injector response after I switched to synthetic oil was night and day in 3 months

I was running conventional Rotella in my '01 Cummins for 7 years and after swapping to a 5W-40 synthetic the injectors stopped chattering and my cold starts dropped from like 4 seconds to instant, anyone else see that big of a change or is my truck just weird?

2 comments

2 Comments

bell.emma2d ago

Got a couple hundred miles on that syn oil yet or did it clean up right away? Because I had a similar shock on my 7.3 Powerstroke when I switched from dino oil to a 5W-40 syn blend, but it took a solid tank and a half of driving before the injector rattle really quieted down. What weight rotella were you running before, was it the 15W-40 conventional? Curious if the cold flow difference alone could make that big a change or if the detergents in the synthetic just scrubbed out years of carbon from the injectors.

jade_hunt481d ago

@bell.emma I used to be one of those guys who thought synthetic oil was overhyped and just a waste of money. But after switching from Rotella 15W-40 conventional to a 5W-40 full synthetic in my 2001 7.3, I changed my mind completely. It took about 300 miles before the injector rattle really smoothed out, and I swear the cold starts are way quieter now. The detergents must have scrubbed a ton of carbon out because the oil came out black as coal at the first change after the switch.