hey fellas! interesting discussion! i'm by no means an expert, but here's my take. certain more 'special' or non-mainstream engines are 'run in' before leaving the factory. for instance, my 1990 Corvette ZR-1 with the hand built LT5 quad cam motor was run in on a dyno for about 10 mins before it left the factory many years ago. all of the ZR-1s were. but standard L98 Corvettes didn't have this done to them. I believe that all Porsche GT3 and GT2 cars are 'run in' at the factory similarly (but I don't think base 911s or Boxsters etc get this treatment). i'd totally believe it that our Cummins 5.0s are run in before leaving the factory too. what I'd dispute (mostly this is a phrase-ology thing) is that the engine is 'broken in'. I'd say that to break an engine in totally takes many hours and many miles to totally 'break in'. as an example, I bought my 2016 XD Cummins brand new (less than 20 miles on the clock) and over a period of 5k miles or so (thats when I did the first oil change) the fuel mileage steadily increased, and it's oil consumption steadily decreased (in the first 5k miles I burned 3 qts of oil). after the first oil change til now (i'm at 12k miles and about to do the 2nd oil change) i've not had to add any oil at all. (it's totally sealed up the rings etc). I didn't baby my Titan in any way, in fact I was pretty tough on it. within the first 400 miles it was hooked up to my enclosed car trailer and towing my racecar all over the eastern seaboard. I use it like a truck and use it hard about 80% of it's total mileage.
so yea, I'd bet that they run our engines in for a certain time at the factory; but I personally wouldn't call that totally 'broken in'.
PS all the engines in my road race cars are run in on the engine dyno stand after being rebuilt. the run in takes about 20 mins and is a certain procedure of rpms. then the oil is changed and the valves reset and the heads torqued and then they are dyno tuned (takes about an hour or two. engine is run up to max rpm and max power til it's putting out what is expected). at that point the oil is changed and the valves checked again and then I put the engine into my racecar and race it! I still don't consider it totally 'broken in' til 2-3 race weekends have gone by (probably about 8 hrs of racing time on the engine). at that time I change the oil again and it's fully 'broken in' and at it's best most powerful state. after that it begins the slow steady decline of 'wearing out' lol!
2016 XD PR 4x4 Cummins
Last edited by d15b7; 04-10-2019 at 09:38 AM.