Geez - I don't read the group for a couple old days and I see a tempest about
oil in OD transmissions.
First, NO after market manual is reliable - they copied factory specs for the
most part, as they were intent on getting the manuals out and selling, and
did no original research that I am aware of. In many cases they screwed up
when they copied, or cited the wrong model source, etc, so they are, all in
all, a secondary source that is of dubious quality.
Second, the factory manuals, which of course should be the Gospel according
to St. Abingdon, also screwed up once in awhile, but not nearly as often. You
sometimes see procedures that must have been written by a cross-eyed person,
or someone with a left/right ambivalence.
But back to oil for transmissions. For the street, a straight 30 weight works
well, and for racing, a 50 weight will give laggy shifts until warmed up, but
then continue to function all through a race, where a trans gets one hell of
a lot hotter than an engine does.
You cannot compare the small Laycock OD unit with the larger series used in
Triumphs, for instance, which as a matter of routine used 90 weight oil and
seemed quite happy with it. Whether this was a function of the passage sizes
in the larger units I cannot say.
And you purists that are worried about detergent oils and foaming - forget
about it! Engine oil works just fine in the trans, and causes no problem at
all attributable to the use of detergents. This is from 3 decades racing and
street driving experience, and close contact in the 70s with Castrol
technical reps and the factory, locally and by correspondence.
The whole thing reminds me of the MG TC guys swearing that you shouldn't use
detergent oils in their engines (which weren't available when the cars were
produced). Then to prove their point, they would cite some guy with an
unrebuilt original engine, probably with a 1/4" deposit of gunge throughout,
from 40 years of using nondetergent oil. Big surprise - when you start using
a modern detergent oil in that case, it starts to pull all the gunge into
suspension and CAN cause problems. That isn't evidence that 'new' oils don't
work with TC engines, mind you. In fact, on a rebuilt engine of any kind,
modern oils do a much better job than the old ones ever did.
I used to hear the same thing when I as racing at Monterey with some of the
old cars - they swore they HAD to use Castrol R despite the fact that modern
racing oil was actually better, the R was hard to get and expensive, and
turned to mush in a sump over the winter sometimes, etc. On the other hand, I
always wanted to add a little R to my sump, to see if using it as an additive
could produce that wonderful scent so reminiscent of racing in the early
days. Makes you want to sit on the floor, turn the lights down, put on the LP
of a BRM or F1 Aston running by at red line, and use the eyedropper to add
some Castrol R to the hotplate, while we all close our eyes and journey to
yesteryear.....
Bill
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