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I know a couple of racers who have the castrol 90W/140 in their box aswell. They do full season (8 raceweekends) with their oil and do service off season. Change oil and check diff. Never heard of weird noises or excessive wear with the castrol and haven't experienced it either. I've raced it too little to give a good experience feedback, but it did run fine in 2 heavy racing weekends with qualifying and 1/2 hour races on Saturday and 1 hour races on Sunday.

To be honest I don't think the viscousity of the oil is extremely important, it's only viscousity.
The quality of the oil is much more important.
Actually, the hypoid would be the dimensioning part and if that works with an oil with less viscousity there should be no problems at all in the clutch packs.
Less viscousity means less friction in the gears and bearings means less heat.
If you switch to a higher viscousity oil because you think you need it due to high temp you are thinking backwards, the oil will not take higher temps and degrading will accelerate over about 140*C in really all oil.

So buy GOOD oil, stuff you know will work and not "magic infomersial stuff with a flashy label you never heard about "
Also look for GL5 and possibly "LS" if you worry about noise.

Dennis , Mats thanks again. Off to import my castrol. BMW will not tell me where they get oil and want R5000 bucks for it. Which is nuts. That like the price of a GTA crankshaft . I feel sorry for BMW owners here out of motorplan.
Castrol lsx 90 is only R300 just to give a comparison.

http://cgi.ebay.de/Castrol-SAF-XJ-SAE-7 ... 286.c0.m14
Wrong language but you get the idea

Thanks Maurizio, I can read that as its similiar to Afrikaans. Ok so I am now convinced its the right oil as it has the codings for LS units.
The codings are as below quoted from wikipedia
'' API GL-5, oils for severe conditions. They contain up to 6.5% effective antiscuffing additives. The general application of oils in this class are for hypoid gears having significant displacement of axes. They are recommended as universal oils to all other units of mechanical transmission (except gearboxes). Oils in this class, which have special approval of vehicle manufacturers, can be used in synchronized manual gearboxes only. API GL-5 oils can be used in limited slip differentials if they correspond to the requirements of specification MIL-L-2105D or ZF TE-ML-05. In this case the designation of class will be another, for example API GL-5+ or API GL-5 LS. ''
if any one interested check ''gear oil '' in wikipedia.

Gearbox oil update.
MD this is the best reply fromall the oil companies I have emailed. This is the same oil Jes runs.
''Thank you for contacting Red Line Oil, your transaxle I believe is shared between the transmission and the differential? As a result you need a fluid that will provide good shiftability plus compatible with the final drive and limited slip.
In your transaxle I would recommend the 75W90NS, matches the viscosity called for and isn't too slippery for the synchros, plus it is a GL-5 gear oil providing protection if equipped with a high offset hypoid final drive. The "NS" fluids provide the proper coefficient of friction for good synchro performance, good shiftability. The 75W90 and 75W140 both contain a friction modifier to control chatter from a clutch type limited slip when making a slow/tight turn on the street, but would be too slippery for the synchros. Generally chatter is not an issue with transaxles, certainly not in a race car as you aren't making slow/tight turns except possibly in the pits, then if present just a slight annoyance. The 75W140NS would be an option if you required a higher viscosity though wouldn't expect it to be required and would likely be substantially stiffer shifting compared to the 75W90NS. ''

Red line is the oil I use.

John

Kevin, is it possible your gears are loose on the mainshaft? Local tuner Vin Sharp showed me a TS mainshaft where the gears all had a little bit of play(axial and angular), ultimately allowing the pinion to move in and out of mesh with the crownwheel. This play was despite the mainshaft nut still being tight and staked.

Scott

Scott, that was all checked. It was a 100% oil failure. Thanks

scott.venables wrote:Kevin, is it possible your gears are loose on the mainshaft? Local tuner Vin Sharp showed me a TS mainshaft where the gears all had a little bit of play(axial and angular), ultimately allowing the pinion to move in and out of mesh with the crownwheel. This play was despite the mainshaft nut still being tight and staked.

Scott

They better be "loose" because they need to be able to spin freely when not engaged. However, there are sleeves which form the inner race of the bearing as well as providing a solid piece to torque down the axle bearings to.