On Thu, 21 Jan 1999, Jeff Johnson wrote:
> Tom and fellow listers,
> General Motors had to go with a synthetic oil in the Corvettes' engines
> because they had a design problem. On cold start-up, conventional motor
> oil could not flow fast enough to lubricate the overhead cams and major
> damage resulted. So, GM specified synthetics and that took care of that
I assume you are talking about the LT5 (ZR1) engine. The LT1 engine
(pushrod GenII SBC available in 91-96 Corvettes, 93-97 Camaro/Firebird,
94-96 Impala/Caprice/Roadmaster) was always shipped from the factory in
'vettes with Mobil 1. The official reason was that the C4 always was
marginal on cooling and with the reverse flow cooling thermal breakdown
was an issue, so an oil cooler and synthetic oil was specified. However,
on F-bodies and Caprices, dino oil was supplied and specifed for changes.
An oil cooler was available for F-bodies with 6-speeds however. I think
the whole synthetic thing in vettes was more of an exclusivity thing than
engineering. (Sorry about the no LBC content above, regressing into
a past life, Z28 6spd).
> On an LBC note, many listers have indicated that the use of
> synthetic motor oil in their cars has caused the engine to leak even
> more than normal. According to a tech rep from Pennzoil, there is more
> than enough anecdotal evidence to support this as fact.
> Since the synthetic flows better, it will make its way out through any
> pin holes or hairline cracks of an older gasket, and then, if you switch
> back to regular motor oil, you'll still have the leak. Just a caution to
> anyone who hasn't put a synthetic in their LBC- the downside of leaks
> may override any benefit of the synthetic's lubricating properties.
I ran mobil 1 in my Z28, and after about 30k miles it would drip a couple
of drops out of the rear main seal if parked for a week or two. I was
told by the dealer mechanics that this was due to using synthetic and
not to worry about it. I didn't. Once I finish rebuilding the TR6 motor
and breaking it in, I may consider running synthetic in it as well.
Certainly if your are mosquito fogging (hi Dave M) or rust proofing your
frame while driving you proabably are just throwing good money away.
Brian Ricker firstname.lastname@example.org
'70 TR6 CC56818L