Ok guys so last september I had the unfortunate case of something inside my diff case blow up, luckly when it happened I wasn't to far from the garage and I was able to drive back with a beautiful clanking soundtrack!!! I ordered a used diff case, drained it and it had some humidity/water mixed with the oil, installed the used case and poured in some fresh Motul 90PA (oil I had laying around from back in the days when I had a AE86 with a Kaaz 2-way lsd), drove for a few days, drained the oil again and poured in some more oil, parked the car in november and only started driving the S2k a few days ago.
I've had a problem with it seems it only showed up when I installed that diff case, its like when brake rotors are touching the shield plate but it only happens at specific km/h , 32-33km/h and 50-52km/h, either if I am accelerating or slowing down, it doesn't happen until the fluid warms up so now during these cold days of spring it taken about 15-20 min. before it appears.
I was thinking of draining it again and use the rest of the Motul 90PA and top it up with a bit of 80W90 gear oil, make it slightly thicker because the noise seems to not apear until the case warms up and the oil thins out, is there a thicker oil you guys would recommend?

Also what is the cause of the diff cases "exploding"? I remember reading last summer when it happened to me that some bolts stretch and cause the ring gear to not mesh properly with the pinion gear and they chew each other but my memory is fuzzy, which bolts are these? the ones that hold down the diff+bearings? I have to open up the case someday and see what went wrong.

Anyways I just want my current diff case to last for a year or so until I put some money aside to purchase a J's Racing 4.7 final gear drive and a 1.5 way or 2 way diff, I want to go to the track and don't want to come back on a tow truck.

 

Buy some Amsoil Severe Gear 75w-110 or 75w-140 and you'll be safe.

 

thanks for the advice, i'm going to look up for Amsoil sellers on the west end of toronto.
See if I do an oil change this weekend and then let you know how it sounds.

 

A contact of mine hooked me up with some Lubrication Engineers (LE1605), which is an SAE110, Im going to run it this summer and have it analyzed to compare it to my run with Amsoil 75w140 last year, should be interesting.

 

This. Lubrication Engineers is the way to go.

 

I know my contact ran it in his differential for a season and when he had it analyzed it had much lower wear numbers than previous runs he had, it looked pretty impressive, as long as you don't plan on running it in winter as it gets pretty thick in cold temps being a single grade fluid.

 

I don't have winter tires so I usually park it during the month of november and bring it back out at the end of march/beggining of april, Lubrication Engineers.... mmm I'll look it up.

EDIT: wait a sec. LE1605 is not automotive gear oil, that is industrial gear oil according to the webpage......wow that is extreme, definitely worth a shot!!

 

there is some confustion about that listing, I don't know all of the details but it is perfectly fine for automotive use and many people have been using it for years along with the fluid that preceeded it.