I am a dedicated Amsoil proponent. Pretty much all I use. That being said, when I built (rebuilt) my 612, I changed the tranny and diff fluid with the Amsoil 75w90 Severe Gear product. I have used it in all my Alfas and my Maserati QP. Turns out that my diff is "chattering" when starting from a stop and turning at the same time. It appears that though the product says it works fine as is for most limited slips, Amsoil states that if you experience chatter, you need to add their AMSOIL Slip-Lock friction modifier additive. I will try adding that and report back if the issue is resolved!
Jason- Add very small amounts until the chattering stops. Like an ounce at a time. Too much and you will make the synchros too slippery to do their job and you will start getting graunching. Incidentally, Valvoline synthetic 75W90 does not chatter in my 575M with essentially the same transaxle.
Taz, that is great advice. Thank you. They recommend 4 ounces and suggest that will do 2 to 4 qts. The manual suggests it holds some like 5 liters. I think you only really get out about 3 and some change but probably get more if you blow out the cooler. Do you think maybe start with 2 ounces or do the 4 ounce tube (it comes in four ounce tubes)?
Totally different (but similar) was the whale oil additive to GM positractions. It did not take much.......seriously. It was a one or at most two ounces, but of course did not have that kind of volume.
Jason- I would start with one ounce. You do not want any more in there than it takes to do the job. May be a little more work that way, but too much is way too much.
Yeah, I figure if I tune it for "just enough" with the cold weather, it will be flawless in the warmer weather. Check my logic...
Bob- That is the noise the gears make if they are not properly meshing. Grinding might be a good synonym. If you have driven non-synchro boxes, the noise most low timers make when they shift gears.
