running new piston rings and bores in ?

Originally Posted by johnnyrod

oh look, free extra power available right off t'internet...

One question though, it was always said to use any old crap oil for running in and not good oil, then change it for good stuff after the first period (e.g. 600 miles) otherwise you'd always (?) get a smoky engine. Any real truth in that?

Modern syth oils apparently lubricate so well that it will take a long time to bed the rings in. Thats why its said you should use standard mineral oil.

Just repeating what is said elsewhere on the internet though, no way of testing this myself.

I personally would change the filter after the bed in process, because this is the time the engine will experience the most wear in its lifetime.

[embee]

Originally Posted by johnnyrod

... it was always said to use any old crap oil for running in and not good oil, then change it for good stuff after the first period (e.g. 600 miles) otherwise you'd always (?) get a smoky engine. Any real truth in that?

In essence, no. Use the regular oil, 10W-40 semi synth bike oil (JASO-MA). Very basic oils tend not to have the anti-scuff properties (cheaper additive pack), and you still want to protect for that.

In simple terms fully synth isn't "slipperier" or anything, it has better stability and high temperature capability than "traditional" mineral oils, so it can offer better protection under extreme conditions and will offer a longer service life, that's it in a nutshell. By high temps I mean local surface temps between rings and bores, which can be 160C+, not bulk oil temp in the sump (more typically 100-130C).

There's plenty of tech reading on the 'net, but try this for quite readable and accurate stuff.