Running an engine in... ?

[g11ary]

I have noticed it myself, so know it to be true, but why?

[civicboy28]

I think its to do with if you run a car in at low constant revs you actually end up just polishing all the high spots, rather than wearing them down, to create a better path for the piston to go up the barrel. Like wise if you run in too hard, you can end up catching a high spot/lip of a port and chipping could happen.

I think with most modern cars you really dont need to run them in, as the manufacturing tollerences are so tight now.
I used to work at ford, and most of the brand new cars are doing 100mph between dealerships on their first day.

[DMDRIFTING]

I used to work at ford, and most of the brand new cars are doing 100mph between dealerships on their first day.

I think thats why ford\'s are ****** or repaired daily lmao

In all fairness, i\'ve been trying to find a website, on the running in of piston engines, and that 90%+ throttle should be used very early on to achieve maximum seal, all backed up with research/stats and proof.

Very interesting, also never use fully synthetic oil on seals or rings while installing!