[AlanM]

I'd definitely err on the side of doing the oil changes early.
I recently bought a mk4 Mondeo cheap with a "stuffed" powershift.

It was behaving pretty badly, slipping,lurching, missing gears, it was questionable if it would make it home. On the positive side, shifting manually seemed to find every gear, and running in 6th at 100 was excellent.

I'd sourced a reconditioned transmission in Melbourne for $2000 exchange, plus freight.

I decided to gamble $250 on servicing the mechatronics unit and changing the fluid and cartridge filter before going to the length of pulling out the gearbox.

There's a series of videos on YouTube on pulling out and cleaning up the valve body, solenoids etc. I'd decided that if I found bits of spring retainers in the fluid or filters, the box was going. Luckily I didn't find even a fragment. The fluid was absolutely filthy and smelled burnt though.

So I basically followed the videos. Some of the solenoid valves were virtually stuck solid and quite difficult to extract. I actually sanded hard scum off with wet and dry paper. They moved nice and smoothly afterwards.

I ran Forscan and did a clutch and shift fork relearn, and the transformation was amazing!

Not perfect, but much better. I'd done the clutch relearn at the minimum allowed temp of 40', so I decided to do it again at the Max 70', since the transmission seemed to be worse when hot.

That made a huge difference, and a few hundred km later the transmission is pretty bloody good.

So, in a very long winded way, I guess I'm saying the fluid can make a huge difference and even though it's not cheap, it's an awful lot cheaper than the best priced reconditioned transmission you'll find. And a lot less work!