TripleS wrote:A few years ago I read an article in which it was claimed that tests had shown that engines that were driven really hard from new delivered a greater power output than those that had been carefully run-in. This, by the way, was referring to motorcycle engines rather than car engines, but I don't know if this makes any difference. I also don't know what effect this 'flog them from new' technique had on the durability of the machinery, but I suspect it could lead to a shorter life.
I've heard the same about cars, about power but also in relation to oil consumption - e.g. if someone made use of the full rev range from the start, it would typically consume less oil for the rest of its life, especially when later owners came to drive it that way. I've heard this many times but I have absolutely no evidence for it.
TripleS wrote:In any case, running-in, as we used to do it, now seems to be unnecessary, at least with the sort of cars I've known this last few years. I imagine this follows from improvements in design, materials, tolerances, surface finishes, lubricants, and who knows what else.
Possibly the ECU maps on cars might handle what was traditionally the 'running in guidance' for you to some extent; again there's a bit of anecdotal stuff that says, 'oh my new car started responding better after 1500 miles' or whatever. Plus it might well have been 'run-in' in the factory by automated testing, I'm not sure. Definitely less of an issue at the user end though.