BW65 - advice on changing oil please

[KansasCityMilkman]

I topped up my gearbox with the wrong type of oil last year (Dexron). I don't think it's done any harm however I want to replace bottom gasket so will replace with correct oil. My question is whether to drain the oil whilst it's hot or to do it when cold? I appreciate oil in the torque convertor won't drain much.
Thanks.

[Lingen]

I gather that Dexron is bad news in B.W boxes as it degrades the clutch lining material. Perhaps it hasn't had time to affect yours yet! I wouldn't drain it at any temperature that might scald you if you spill any, but it will drain better warm than cold. The trouble is that there will still be a lot- possibly 50%- of the contaminated oil left in the torque converter that you can't drain out. I think it might be worth getting professional advice to find out how best to rectify the problem. It may be that if you didn't add much Dexron, there is nothing to worry about.
Mike.