I think this is the main confusion of this topic in general.
The specs for 90wt in the O/Ds isn't just viscosity related...
its the other temperature and shear specs involved in the differences between
'gear' oils and 'engine' oils. at various operating temperatures
90wt gear oil viscosity at 40°C is in the neighborhood of 70-100 while the
a 20W50wt at 40°C is closer to 100-150 but both are with 10 of each other at
100°C
The flash points of gear oil are usually in the 200-250°C range
while engine oil specs have a flash point a bit higher in 220-290°C range.
If you're in cooler, damper climates. engine oil is fine
warmer climates...stick to the gear oils for the retention of the shear
properties
(better syncho engagement effects)
So what does all this mean? Both will work fine on the street.
You're driving habits will have a greater effect if you maintain 'clean'
oil in your car.
On the track is a whole 'nother ball game.
Anyone that's wants cold hard numbers on all this can go directly to
http://www.mobil.com/index_flash.html
http://www.redlineoil.com
http://www.castrol.com
among a zillion others that list all the specific properties of their products.
(I only named these do to recent email threads naming
these as a few people use.)
Paul Tegler wizardz@toad.net http://www.teglerizer.com
----- Original Message -----
From: "Nolan Penney" <npenney@mde.state.md.us>
To: <spitlist@gte.net>
Cc: <spitfires@autox.team.net>
Sent: Thursday, August 31, 2000 7:32 AM
Subject: Re: Tranny oil
I think actually the lower viscosity oil recommendation had to do with Laycocks
oil specifications for
their transmissions. They do not recommend the standard 70 to 90 weight gear
oils. I think they
recommend about a 50 weight gear oil or an equivalent weight motor oil. I can
try to dig this up
if you like.
>>> Joe Curry <spitlist@gte.net> 08/30 3:13 PM >>>
That is likely to be expected in colder climes. I think it is why earlier cars
(TR3/4, etc) had recommendations of using engine oil in
the OD transmissions.
Joe
A666K@aol.com wrote:
>
> I have some Redline in my newly installed OD. I experienced some slipping
> from the OD right after installing, and only when tranny oil still cold.
> Hasn't happen much since then (about a month since completion), I'll put on
> another 500 miles or so before deciding.
> Hope this helps,
> Avi
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