--- Daniel1312@aol.com wrote:
> a hot running engine in a Spridget fand the centre
> bearing and oil ways of a
> turbocharger unit. STP is fine for the
> Sprite/Midget unless it is
> turbocharged in which case a straight synthetic is
> all that should be used.
Yup. Biggest problem with turbo bearings is "coking",
that is, a hard carbon deposit from the "burnt" oil
that forms on the bearing surface from excessive heat.
The deposit is diamond hard, and will micro scratch
the bearing surface, which quickly runs away into a
seized bearing. I've seen this in both journal
bearing and ball bearing machines. That's why turbos
that do not have reservoirs that provide oil after
shutdown should be idled for a few minutes to let the
oil cool down and circulate throught the bearings at
low turbo RPM. Aside from their better high temp
properties (and heat transfer), synthetics do not
coke.
=====
Ron Soave
"You Are What You Remember"
1960 Bugeye
1972 BGT
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