Advice on "Running In"

[Calais]

Seems to be a bit of both schools of thought here. My way sure is fun though......

In the end.... its your car, run it in however you like.

[Pietra]

bugger

And under no circumstances drive a new engine at constant revs for a long period. A trip up the Hume or down to Geelong on cruise control is the worst possible thing that you can do despite the fact that you are adding miles.

I really hate to ask this but why is this the case?

And can we put a definition to new in terms of kms?

[Calais]

I really hate to ask this but why is this the case?

And can we put a definition to new in terms of kms?

It has been explained to me as a way of ensuring that the engine rotating assembly is put through a varied range of temperatures and loads, to ensure rings, bores and the valvetrain to bed in correctly, and to "harden" metal parts during the early stages of life (ie first 5000km or thereabouts) by cycling them through a number of heating and cooling processes.

A lot of people will say that it just a pure wank... and I tend to agree with them... for a mass produced engine anyway.

(As mentioned earlier, I couldn't really have cared less. I drove my car normally from day one, and it's never given a days grief.)

[Pietra]

Calais - thanks but I was more seeing why K1W1 was saying a long trip on Cruise Control at relatively consisent revs was bad

[K1W1]

For the reasons Calais explained.