My question with the transaxle lube is more related to balance (I think)- what is best for the synchros and gears and what is best for the torsen LSD? I've heard good things about the Ford XT-M5-QS, which apparently is manufactured by Castrol and sold by Castrol under their own name in Europe. In my '83 BMW 533i, it is easier to have a solution- Red Line MTL in the trans, and Red Line 75W90 High Performance in the rear end. But with the MazdaSpeed, it's all in the same case. The guys who run the Red Line MTL in their MazdaSpeed 3 cars say that while shifting is smoother, LSD low speed turn chatter is present. And if friction modifiers are added, it may be to the detriment of the synchros. The factory fluid in this new car is fine for now, although from my BMW experience, normally all ///M cars get the engine oil, transmission fluid and differential fluid changed at about 1200 miles. While this may or may not be appropriate for the MazdaSpeed 3 DISI Turbo car, I thought of it as a good starting point. However, the nearest Mazda dealer (who I have a Thursday morning appointment with to do an oil change, hopefully they'll use the correct weight oil) says they don't have any particular recommendation for the transaxle other than the 75W90 dino fluid. Of course, the service writer also stated something about the turbo having bushings and not bearings, and the motor being better off with conventional motor oil over synthetic. I don't know enough yet about the car or specifics of oil to have much of an opinion on the subject, but when he said this, my B*(($%!t meter started moving. I just want to treat this engine and driveline right from the start...
