Larry is correct. When I taught Aircraft Powerplant Lubrication Systems I
had a guest speaker come in who owned a small oil and grease production
company. He had a chart that showed how one oil is rated at different
viscosities if it is measured as a gear oil or as a motor oil. If I was at
work, I could look at it, but I think Larry is correct that SAE 40 engine
oil has about the same viscosity as SAE 90 gear oil.
Notice that I say SAE 40 not 40 weight. The numbers assigned by SAE have to
do with viscosity, and have absolutly nothing to do with weight. There is an
API (American Petroleum Institute) specification for oil specific gravity
however.
Then the student always asks "then what does the W mean as in 15W50?" It
means Winter. 15W50 means the oil meets the SAE spec for Grade 15 when it is
cold and it also meets the spec for Grade 50 when it is hot. Forgive me, but
my pet peeve is people saying "30 weight"! Sort of like mjb and his 67 foot
long Chevrolet. It's my job to correct people so it's hard to break the
habit.
Just my $.02.
J.R. Herrera
1957 TR3 Jackstand Queen
1959 TR3 Old Reliable
>From: Larry Young <cartravel@pobox.com>
>Reply-To: Larry Young <cartravel@pobox.com>
>CC: fot <fot@autox.team.net>
>Subject: Re: Gear Oil
>Date: Thu, 16 Jan 2003 19:31:04 -0600
>
>With this recent discussion of gear oil and shock oils, it is important to
>point out that (if I'm not mistaken) there are completely different
>standards for reporting gear oil and engine oil weights. On engine oil,
>the
>
>upper number is based on the viscosity at 212 degrees F. Maybe someone can
>clarify this, but I believe gear oil goes by a completely different
>standard. and I have no idea about hydraulic shock oil. So if you think 90
>wt gear oil is heavier than 40 weight engine oil, you may be wrong. The
>information is probably out there someplace.
>Larry Young
>
>riverside wrote:
>
> > We received a recommendation from a Lapenis
> > specialist to use non detergent 40w oil in the J-type.
> > (30w nondet in cold weather). Anybody doing this?
> >
> > art de armond
> > -----Original Message-----
> > From: Joe Curry <Spitlist@gte.net>
> > To: Friends of Triumph <fot@autox.team.net>
> > Date: Wednesday, January 15, 2003 4:13 PM
> > Subject: Gear Oil
> >
> > >Thanks to all who have replied to my gear oil question. The consensus
> > >appears to be that my assumption (the synthetic oil is too slippery for
> > >the synchros to function properly) is correct.
> > >
> > >I will be looking at the recommended solutions and choosing a more
> > >suitable lubricant.
> > >
> > >Thanks again,
> > >
> > >Joe (C)
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