Thanks Rabin. The problem is that I gave out the job of changing transmission oil last Autumn and haven't driven the car much since then for various reasons including having to change the engine mounts. It seemed OK except for some minor leaking which I put down to old age (the car that is!). Having eliminated the steering, I dipped the trans and noticed the overfill. We have an Acura which, when changing the trans oil, requires filling until the high mark on the dipstick, as per an engine oil change. I suspect that the mechanic did the same when changing the 505 trans oil. I have drained the oil which looks OK, fairly clean, no smell and probably about a litre more than I expected. My concern is whether any damage could have been done internally without being noticed, so far. Cheers.