[AlanM]

This is amazing. I just bought an MD very cheap at the auctions which had just had a transmission service done at MyCar auto. It had the "Transmission limited function" lit up too, and in fact couldn't be driven, I had to tow it.

I discovered the transmission only had a little over three litres of oil in it. (They had charged for the full 6.2 litres though.)

There's a procedure to changing the transmission oil in these. It's a bit of a rigmarole. You can find videos on YouTube, but basically you fill it till oil runs out a level hole, refit the bungs, start the car, go through all the gears a few times, shut down the car, take out the level bung, some oil will drain out, you have to wait until it stops, then add more oil until it starts to run out again. Then it's full.

There are two chambers in these transmissions, the front has the pump and valve body, the rear has the actual gearbox. The front chamber is higher than the rear and they are separated by a weir. You fill via the front chamber which overflows into the rear, where the level drain is.

What happens is when you drain the oil, it (mostly) emptys out the valve body and all the passages too. When you refill it, it fills both chambers but not the valve body etc. So you have to run it through the gears. Which then means the front chamber isn't properly filled until you top it up again.

Doing it properly takes a while, which is probably why they so often don't. You have to remove the undertray obviously, but also the left front wheel and the inner mudguard.

Anyway, as said above, they take a bit more than six litres. But even if you put six litres in without going through the process, you'd end up with an overfilled rear chamber and an underfilled front one. And possibly a "Transmission limited function" message.