RE: Manual transmission oil: what is the best (long)

["Jeff Greenfield" <alfaguy@xxxxxxxxxx>]

The problem with most synthetic gear oils is that they have friction
modifiers in them that actually make them too slippery. A conventional
manual transmission requires a certain amount of friction for the
synchronizers to work properly.

The reason for the friction modifiers is so that the oil can be used in
limited slip differentials. These require the friction modifiers so that
friction discs in the LSD won't chatter.

Using any of these oils in a conventional manual gearbox, will actually in
most cases make them shift more poorly, and will exasperate worn synchros or
those that are on the verge.

For a 105/115 car, if you wish to use a synthetic you need to use an oil
such as Redline MTL, or their 75w90NS. Either of these will work well, meet
the proper specs for the application and do not contain any friction
modifiers. There are probably others out there as well that do not contain
the friction modifiers, but I don't know of any off hand.

For a transaxle car, without a LSD (Alfetta, GTV-6, Milano, etc - I don't
what the 164 calls for) you can use the 75w90NS as this is a GL5 spec Hypoid
oil.

The interesting dilemma occurs for those of you with a LSD transaxle (Milano
Platinums and Verdes if memory serves correctly). In these boxes you need to
use something that has SOME friction modifier in it to keep the LSD happy,
the problem is that this has a negative effect on the synchros. According to
the people at Redline, the best thing to do in these applications is to use
the 75w90NS with a small amount of their friction modifier which is
available separately from them. You want to use approx. .5% - 1% by volume.
Start out with the lesser amount, if the LSD 'chatters' at all, add a little
more. The 75w90 has approx. 5% friction modifier in it which is too much for
the synchros in the gearbox.

If you have a gearbox or transaxle that has had a synthetic oil in it that
does not work well it can take quite awhile to restore proper function. The
best thing to do is to change the oil in it when hot. Run the car for a bit,
maybe a few hundred miles, and then change it again. Don't expect immediate
results, in can take quite awhile.

I went through all this on my own non-Alfa LSD transaxle equipped car a few
years ago. I tried several different oils in it in an attempt to improve
(well actually restore the shift quality to where it was before I put the
synthetic in it). The 75w90NS with a small amount of friction modifier did
the trick, but it took several thousand miles for things to return to
normal.

And yes, after all this, I still prefer synthetic in a gearbox as it works
much better and is kinder to the synchros when cold.

Jeff




Following the last debate about AFT in tranny, what is the best oil to put
in
a manual transmission for the spider 3 series ?



I changed the tranny oil last winter in my 1986 spider for generic synthetic
80W90 oil.



Yesterday, I drove my car for the first time since last October and I heard
sound coming from the tranny in neutral. Also, the syncho feeling was quite
different as well as the shifting and I had to double clutching to
retrograde
(OK that is not so bad).



The new oil doesn't seem to have improved but rather diminished the previous
smooth shifting (if possible for an ALFA) condition of my tranny.



Any tips ?


Damien
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