Coolant tank colour & residue..

[pistoncranky]

Hi,
My 2012 (delivered 02/13) 132 TSi 2.0 is up to 56,000kms and due for the 60K/5yr service which will flush and change the ATF and the coolant system plus other oils, filters & plugs etc (brakes were done at 50K at this time last year because of the time interval and pad change) - last year the mechanic said the coolant was weak but I took it as an observation rather than a prompt to change it and he said it was okay.

I have noticed that the coolant reservoir / overflow tank is discoloured a dirty brown / reddish almost rusty colour and the fluid was a bit reddish but quite clear. I have stuck my finger inside the reservoir and wiped some rusty brown coloured sediment / residue off the inside of the tank and one of the sensors / inlets and it was quite gritty.

Has anybody else seen this or have any knowledge of that kind of thing?

Thanks,
Chris.

[Umai Naa!!]

It would seem as though the coolant concentrate is no longer ideal, and corrosion is setting in. Definitely time to flush the coolant, and give the expansion tank a clean-out.

[pistoncranky]

The expansion tank has been replaced and the coolant flushed so it all looks pretty and pink!

I was told that the Tiptronic Auto doesn't require an ATF service and the unit is sealed for life.. not what I thought I read here or in keeping with my past knowledge of A/Ts - any ideas about that. Does ATF not get contaminated by friction material?

I was also told that the rear bevel drive (differential) was a no-service-required unit and neither was the front one and that changing oil in these diffs sometimes cause them to have problems - again: who know about that?

I'm wondering about the "sealed for life" concept - is that a warning that you can expect to substitute a few hundred dollars in oil-services on these items for complete rebuilds or replacements costing thousands (or tens of thousands in new car costs)
From ancient knowledge changing oil was an old-school life-preserver.. or is the oil that much better now that they'll go the same distance as before and they always fail at about the same interval.

[Umai Naa!!]

Auto trans is due every 60K or 4yrs, along with the internal filter, although the dealers don't push it due to the shear cost involved in doing it through them.

No service interval on the bevel box (mounts to the transmission, sends drive to the rear wheels), but nothing stopping you from giving it an oil change. No special oil required, just an off the shelf 75W90 full-synthetic gear oil.

Haldex coupling (on the front of the rear diff) oil is due every 3 years from MY10-onwards.

No service interval on the diff oil itself, but again as per bevel box, you can do it if you chose to with the same oil.