Chris mentions an argument on the Porsche mailing list
that talks about Castrol pitting a cam. It's also
been reported that Castrol is not a good choice for long-
term high-performance use in water-cooled VWs for the
same reason.
A couple years ago, a technical marketing guy from
Drake Engineering in Southern California was talking
heavily on rec.autos[.tech?] about his experiences
hot-rodding VWs. As a dedicated fahrvergnuegener,
I paid attention. His experiences seemed to indicate
that Castrol GTX and German metallurgy were incompatible.
Specifically, German camshafts assume the presence of
a particular compound in their oil -- and no, I can't
remember what it was (molybdenum disulfide, I think, but
it's been a while). In any case, Castrol doesn't have
this. This causes no apparent problems in the American
and British cars in which I've used Castrol GTX; I've never
used it in a Japanese car.
As for this:
>I think race teams chose motor oil the same way 4 out of 5 leading hospitals
>chose analgesics: price and sponsorship. Anyway, who cares what they chose?
Well, some of us do because we're race teams. Though price
and sponsorship do enter into it, racing also assumes some
additional tradeoffs that the basic sports-car enthusiast
doesn't face. I ran synthetic (Mobil 1) in the Biscuit Tin
of Steel while I was racing it because of its superior
characteristics at high temperatures, such as I regularly
found on course. In addition, the lower viscosity of the
synthetic (15W-50, but here the 50 reflected more on the
heat range than an actual viscosity -- it's pretty thin)
gave me a measurable improvement in fuel economy (as much
as 2-3 mpg at 75 -- er, freeway speeds :-) and a barely
tangible improvement in top-end (5500 RPM and up) power.
Racers will trade off durability for a few fractions of
a horsepower, but synthetics give both. When I build my
E Prod motor for next year, I will violate the sacred memory
of Captain George Eyston and use Redline instead of Castrol.
Meanwhile, it's Castrol GTX in the crankcase of the street B and
Valvoline in the GTI now, to be replaced with Mobil 1 soon.
And yes, I *do* use Castrol in the street B for tradition's
sake. If you can't be traditional about an MGB, you might
as well get a Honda...
--Scott
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