Hi Bud,
I think a lot also depends on what sort of RPM you use when running in. If
the engine has a fast road cam then using 'off the cam, rpm' might be pretty
tedious.
I like to use a cheap 20/50 for the first 500 and then a decent 20/50 for the
next 500 or so. If the rings have bedded in nicely (neglible to zero blowby
in the oil catch tank (good reason for having a catch tank) its time for 15/50
Mobil One full synthetic.
Chuck makes a good point about what the engine builder recommends because
only they know what sort of job they have made of honing the bores (or do I
mean
glaze-busting??) and how long the rings will take to settle in. I don't know
much about the bedding in of the other bearings (mains, big ends etc) and have
always thought the real issue was how the rings seal.
I once ran in an engine on Mobil 1 Synthetic and from memory in ran in better
then the next rebuild when I used the 20/50 but this probably says more about
the rpm and way I ran in the engine (ok for short burst of high rpm....)and
generally the use of a Synthetic for running in is not recommended. If you
have any feel for the engine your'll feel the engine getting looser and more
willing to rev and rev quicker though maybe for a standard engine rather than a
fast road car engine this may well not be the case.
Regards
Daniel1312
In a message dated 30/03/05 02:01:34 GMT Daylight Time,
cfchrist@earthlink.net writes:
> mineral oils
> and semi synthetic or synthetics are yet another can of worms that is best
> left to the engine builder to explain why's and how-for's with respect to
> each individual rebuild.
> i like a loose fast spinning motor personally. i'm a fan of castrol
> 20-50wt in my tow vehicle and i run straight racing 70wt in my street
> bugeye. (yes i warm it up first!) (and straight racing 60wt in my stroker
> harley motor).
> but! those are motors i built and i know exactly what's in 'em.
>
> chuck.
>
> >I talked to a guy at Elgin Cams today - he said they recommend straight 30
> >weight oil to break in a new engine.
> >
> >I'm breaking in a new 1275 on my street Bugeye right now, and I'm going
> to be
> >breaking in a new race 948 soon.
> >
> >I've been using Castrol 20w50. Shoud I be using a different oil for
> break-in?
> >
> >Thanks
> >
> >Bud Pazur
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