>Kirk's transmission mechanic recommended 20W50 motor oil for the tranny
>instead of hypoid gear oil? Somehow, 20W50 motor oil doesn't seem like a
>suitable replacement for 90W or multi-weight hypoid gear oil.
****************************************
IMHO, gear oil has additives, specifically for the kind of abuse that
certain helical cut gears do to lubrication fluid (fluif). That is the
shearing action that this kind of gear does to the oil during normal
operation. Engine oil does not offer the SAME kind of protection that gear
oil provides. If the manufacturer specifies gear oil, there is probably a
good reason for it. Depending upon the material used in the construction
of the gears, the angle and shape of the teeth, type of bearings, synchros,
etc different mfg's will specify different oil's compatible with their
particular vehicle. Countless hours were (are) spent testing for
durability, compatibility, wear, ease of use, etc., and oils would be
specified as best upon completion of those tests. It isn't just because
somebody owns stock in the oil company. Just because one car mfg specifies
one type of oil as suitable for their vehicle DOESN'T mean that it can be
used in your's. for me anyway, I'll stick to what the manufacturer
specifies - In my Triumphs, its 90W hypoid gear oil - including the GT6
with J type overdrive, and no problems in over 8 years.
Barry Schwartz (San Diego) bschwart@pacbell.net
72 PI, V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (long term project)
|