While I was previously in aeronautical engineering for over 16 years, I am certainly no expert in DSG’s! However, after much research, and having recently completed this myself, the following summary might be useful for others:
There appears to be two methods of refilling, and two methods of determining the correct level.
The gearbox can be refilled by pumping or relying on gravity feed through the bottom drain. This is much quicker, particularly when using a pump (only minutes). The downside is that the official tooling is expensive, and it can be messy.
The top fill relies on a small diameter inlet port, exposed when the filter is removed. While this is slower, I found it very straight forward, and no mess!
As for determining the correct oil level, some simply measure the capacity of oil drained, and refill with the same quantity. Nothing wrong with this, provided the level was correct to begin with, and the temperature of the old and new oil are relatively close. Also need to take into account any oil lost, particularly using the bottom fill method.
I used the VCDS method, which although more time consuming, gave me reassurance that the level was correct. I think this is important, as the oil is not only used for lubrication and cooling, but also for the hydraulics within the mechatronic unit. This method involves overfilling, running the gearbox up to a specific temperature (monitored with VCDS), and then removing the drain plug with the engine running, at which point the oil will drain to the level of the stack pipe.
Concluded with a Basic Adaptions reset using VCDS, the DSG gets a proper treat!
Main dealers seem to be charging less than my local Indy, but I decided to service this myself to avoid the mess (as comment about Audi above), and so that I was certain that the level was correct. It was also interesting to see the condition of the old oil.
