Thermostat OEM Audi or Mahle

I’ve installed Borg Wagner thermostats and those always failed until I installed a Mahle one which never failed. For some reason any other brand will get stuck open and the engine will never get up to temp.

I used Mahle, but I got lucky I got the German-made one (afaik now most are made in Italy). It was NOS so I expect the electrical heater (to open early) to be defect. It's been 3 years without issue though.

I used oem bmw coolant and a mahle thermostat.

I have an 06 Audi A3 2.0T Sportback with just over 105k miles; recently replaced the thermostat, spark plugs and coil packs. Other than being in need of some new brakes and a bit of cosmetic love, she's running strong.

I had a brand new mahle one with the connector wired in reverse for constant. Kept blowing a fuse. Returned it for a replacement and worked fine.

Recently had the exact same issue on a 14 a6 ended up being a DOA t stat I compared the shaft length on the new t start to the 2nd new t stay and sure enough it protruded out about a mm further just enough to not seal properly causing the over cooling after the swap no more issues.

Had this happen to our 2018 Q5 a few months back, 35k miles on the SUV. Thermostat issue plus some other stuff.

Hatte auch schon ein Mahle Thermostat das kurz nach eimbau defekt war. Dannach ein Originales von BMW rein und seit dem wi3der keine Probleme.

Last week changed the thermostat on my 1.9 tdi 66kW to a Mahle TX 15 87D (11€), it was fine for the first two days, then the temps started dropping again.

1st Mahle. The engine only reaches up to 65 degrees and it drops further if I drive under 2000RPMs on highway for example or turn on the heating.