Originally Posted By: callbay
When I was 16 years old ( a lonf time ago) a good friend bought a new 390 CID Mustang fastback. The saleaman told him to break in in hard to have a fast machine so we drove it out from the dealer and out to a "safe" place and took it up to top end.
I have always wonderd if there is any truth to breaking in hard for a faster car or motorcycle.
Comments?
Absolutely endorsed here. Third gen machinist in the family, says the rotating assembly is either right or wrong, rings seat in minutes. Why not expose any weaknesses early?
My car is a known oil drinker, yet my example doesn't use a drop, even at all day long HPDE's. Every new car needs full throttle for break in benefits like better ring seal, lower oil consumption, and higher power.
Note my owners manual language: "Full throttle is beneficial to engine break in"!!!
Previous posters saying that engines are run in at the factory is completely wrong for the overwhelming majority of cars produced. Some high end like HatterasGuy mentioned, but not your grocery getters. TEST MULES are run hard till failure, but regular production motors are RARELY run in in advance.