105/115 gearbox lube

["Dean W. Cains" <dwc@domain.elided>]

Hi Group:

This talk of moly/pre-moly synchro's and EP/non-EP gear oils has me wanting 
to share my experiences.  I bought my current Spider, a '74, a few years 
ago, and at the time changed the gearbox oil along with all the other 
fluids.  It had been a while since I'd had a 115, so without much thought, 
I used 2+ quarts of Mobil 1 75w/90 (GL-5/EP) in the gearbox, the type (but 
not the brand) recommended on the underhood label.  The gearbox shifted OK 
for a while, when the box was cold, but as things warmed up, second gear 
synchro got very weak.  I almost always double-clutch by habit, so this 
wasn't a real problem, except once in a while I'd catch some noise going up 
into second.

Fast-forward to a few months ago.  I was changing fluids again, and this 
time used a 70 weight motor oil (no EP additive) in the gearbox.  During 
the first few drives, shifting was marginally better, but after a week or 
so, it had improved significantly.  Perhaps the EP slime took a while to 
wear off the synchros?  It's been 1500 miles or so, and I'm still impressed 
with the shifting, even up into second without double-clutching.

Rewind to 13 years ago.  I went through a similar process when I bought a 
new BMW M3, which had its gearbox as one of several weak links.  It was 
noisy for certain, but also awful on upshifts.  BMW had changed to moly 
synchro's after '83 (so I'd been told), and that's apparently when the 
gearbox complaints began.  The hot update at the time was to switch from 
factory's 90 weight GL-5/EP oil to Redline's GL-4/non-EP gear oil.  The 
nasty rattling noise was still there, but the shifting was much improved.

The anecdotal evidence I've heard is that the EP oils are too slippery for 
use with the already-slippery moly synchros.  This fact was indeed 
mentioned in Redline's literature back when I changed to their oil for the 
M3, so perhaps there's something to it.  Anyone know for sure?  Can any 
harm come from using a motor oil in the Alfa gearbox?  I've owned quite a 
few other cars (British) that used motor oil in their gearbox, with no harm 
done there.  For the record, the motor oil in my Spider's gearbox now is 
Kendall Nitro 70w, a little over 2 qts.  Any petroleum chemists or 
engineers out there?


Regards,

Dean W. Cains
dwc@domain.elided

'74 Spider Veloce
Lutz, FL

--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided