Design faults in major manufacturer car engines

Its the early four speed + lockup which had the problem. A metal sealing ring wears inside, which isn't a problem until you start revving it in neutral ... then oil seeps past this ring, loads upo the front clutch pack and makes it partially engage. Thus "wearing it out". The later gearboxes (1987 on i believe) had a small oil drain hole drilled to prevent the problem.

A test: Jack the two driven wheels off the ground. Start in "N". Rev a bit (with handbrake off if rwd). If the wheels start turning in "N" you know your gearbox might be killed by the mot tester doing his normal "warm up" before checking the co mixture. If, like mine, (bmw 525e) nothing happens, its still a good healthy gearbox. If, like mine 4 years ago, you could click it into neutral, rev it and have the car creep forward .... the gearbox is about to fail. (As mine did)!!!

Then its a long drive home backwards!!

It was emissions testing in the US which showed this up. And now in the UK where they require the engine to be run at around 2000 rpm in neutral. But older cars don't need this test in the UK, so may well be ok.