I don't know if it helps anything but on my Escos you actuaally can overheat gearbox oil - after WHOLE DAY of practice on the track by 3 people there where some problms with switching gears which I think come form over heating. At the same time there where problems with engine oil pressure at idle so I think the car was genneraly too hot - even inside it was hot as hell on a cool day. But as I say this is after something like 10 hours of time trials and such.