>
> I know this is probably a dumb question, but my manual states that I
> should use 30W Hypoid Oil in the transmission. The only "Hypoid" oil I
> can find in the stores is 85/90W. Someone once told me to use regular
> 30W motor oil. I tried this and the gearbox soon disintegrated,
> leading to the purchase of an all syncro tranny. (Probably a blessing
> is disguise) I am past due for another oil change, but I am hesitant
> to use the 30W motor oil. Does anyone have any suggestions?
I'm surprised your manual recommends Hypoid oil since this type of oil
usually contains sulfur compounds which can attack the copper in brass
synchro rings. But then again, maybe Alpines don't have brass synchro
rings.
BTW, the SAE viscosity ratings for motor oil and gear oil are not
equivalent. I don't remember the exact relationship, but I believe 90
wt gear oil has a viscosity somewhere between 30 and 40 wt motor oil.
30 wt motor is probably about right wt for a gearbox.
Regarding the use of synthetic gear oil, let me relate my own personal
experience. I put synthetic gear oil in the differential, transmission
and rack and pinion steering of my Cobra a few years ago. I used
synthetics that were the equivalent of the non synthetic oils
recommended in the owner's manual. In every case, I noticed leakage
within a few months. The gearbox leak wasn't too serious, just enough
seepage to get things nice and dirty, but the differential and rack
leave noticeable drips on the garage floor.
My understanding is that synthetic oils are highly detergent and can
wash away the sludge that has been keeping 30+ year seals and gaskets
from
leaking. I don't think this is a problem for a freshly rebuilt
transmission, but if it's been a while since you transmission has been
apart, I would avoid synthetic oil. Maybe you'll be lucky and not
develop any leaks, but once a leak starts, there really not much you
can do short of replacing the leaking gasket or seal to get rid of it.
It's just not worth the risk, IMO.
Roland
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 09:21:50 CDT