How long, generally, is a break-in period?

What gears are in the rears?

 

My experiences with break in periods with big diesel engines is fuel mileage and oil consumption. Performance is either there from the beginning or its not. It doesn’t usually get stronger power wise. Fuel mileage should get better and oil usage should go down to zero if break in goes proper.

With gas engines once we ran in the cam for 20 minutes it was full throttle fun at the track. Some guys I know never even spent the time running in the cam. It was assembly, fire up, set tune, race! Lol!

 

I swear I was reading on here the other day the exact same question and someone piped up and said that Cummins derates them until they hit a certain hour/mileage, then they open up.

No idea if there's truth in that or not, just something I "thought" I read on here.

 

If it was a CAT, one would say "drive it like you stole it" and that was a break in. But with a Cummin's Progressive Warranty they'll only pay for the first item that breaks. All the collateral damage downstream is on you (or the carrier). Always remember though, with a Cummins, you're actually getting 2 engines. No really.

 

How does it perform at 1600 rpm?