<VV> Manual Transaxle Oil

[Seth Emerson]

Good Info, Gary - Thanks for checking it out. You came to the same conclusion as others. Thanks for nailing it down. - Seth


-----Original Message-----
From: edward szuch via VirtualVairs <virtualvairs at corvair.org>
To: virtualvairs <virtualvairs at corvair.org>
Sent: Sat, Sep 14, 2019 8:54 am
Subject: <VV> Manual Transaxle Oil

Just wanted to share some info on Corvair transaxle oil.  I know there have
been quite a few discussions on this but I couldn't remember all the
details so I was checking around by phone and Google.  I ended up at the
penngrade.com site which was the old Brad Penn Co now under the D-A
Lubricant Co.  I called the contact number and was eventually put in touch
with a Mr Ken Tiger (sp?).  He said he gave an engine oil presentation at
the Pittsburgh convention but no one had requested info on transaxles with
a hypoid differential.  This issue is the EP (extreme pressure) package
(lots of sulphur) added for the hypoid gears attacks the brass synchronizer
rings and can cause surface corrosion (pitting). Long story short, he
recommended their PennGrade 1 80W90 Classic Multi-Purpose Gear Oil which is
a GL-4 rated oil.  Their part number is #7729 but will appear as a #77296
at Summit, Jegs, Amazon.  The '6 designating a quart bottle container.
Interesting point was that he asked me what the owner's manual said and I
checked mine (1966) and the shop manual and they both said MIL-L-2105-B.
This is a military spec and when he checked his resources, found
information that said it was the same as API GL-4 and other resources
saying it was an API GL-5.  However, some of the info from the API GL-5 was
from later documentation of the mil spec (2105-D, 1995) so his conclusion
was to stay conservative and go with the GL-4 oil.  This oil will not harm
yellow metal (brass synchros) and has a sufficient EP additive package to
work well with our hypoid differential gears.
This oil does not have a limited slip additve (LS) so I'll have to get some
of that for the posi unit in my car.  He said there shouldn't be an issue
with adding it to their oil.  He suggested the GM additive so I'll try that
first.
I bought my oil from Summit for $8.99/qt.  Amazon only sold by the case and
JEGS was selling the GL-5 version with an LS additive.
Hope that helps someone considering a manual transaxle oil change.
Gary Szuch
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