I have a 1993 525i Touring. It has the 5 speed auto (don't know the model number but I understand there are only two choices in the E34 anyway).
I have mentioned this problem previously but now I'm after more advice.

Since I've owned the car last January, on cold mornings it holds on to 1st and 2nd gear for the first 5 minutes of driving. Also - at any time it won't go into 5th unless exceeding 80kph.

When I took it to a auto expert for a service and told them, they said its most likely the rubber o-rings and seals around the valves becoming hardened with age and its only after the oil warmed up a bit and the rubber softened that the valves begin to move properly.
They added a rubber softener to the oil but it hasn't made any difference at all.

I mentioned this problem to a BMW service expert (not a dealer but specialises in BMW servicing and tuning) as I asked him to recommend his preferred auto specialist.
He suggested that I just live with it because no matter what, it was going to be horribly expensive to have any work done on the auto at all - mainly due to the cost of the gasket sets etc.

I was hoping that just the valve body could be dropped out and the rubber -rings and seals etc replaced.
Has anyone done this?
Can anyone offer an opinion?
Is it a job I could do myself or is there a lot of setting up involved (I am an ex-mechanic, but I have little experience on automatic transmissions).
Should I go see the auto specialist or am I wasting my time?

best regards,