Transmission service...
 

I was looking into another A8L. The owner tells me that the transmission is a sealed unit. I find that hard to believe.

I was looking for a car with service history. Control arms, transmission fluid changed and timing belt/water pump replaced. Anything I am missing?

The transmission is serviced from the bottom, and its completely sealed unless you take out the fill and drain bolts on the pan. This must be done with a special tool.

So, is it a straight forward procedure if you have the right tool? You can't fill it from the top?

No, the tool is a gravity feed instrument. Basically there is a tank that you suspend from the hood latch and a hose runs all the way under the car and up through the fill port. You also cannot fill the transmission without the VAG COM, the reason for this is you need to monitor the transmission temperature. If the temp is too hot or too cold you won't get the correct fluid level. Basically it has to be 32*C when you dump most of the fluid in there, before starting the car you put in around 3 liters to prime it, once the fluid starts leaking out of the fill port around that temp then the trans is full.

It sounds like a hassle for the DIY guy. What is the recommended interval for the flush and do you know the cost at the dealer for this service?

Thanks,
Paul

I would do it every 60-80k, no longer than that. Another reason i say that is when servicing the transmission the tech might notice a leak on the pan, torque converter seal etc. which can prevent major problems down the road.

controll arms does not matter - it does not cost so much as transmission and engine. transmission and engine first things to check