Thermostat OEM Audi or Motorcraft

Make sure you use the motorcraft thermostat.

Go with the Motorcraft thermostat as it has a rubber seal on the outside edge.

Not the water pump but I just had my thermostat replaced under the extended warranty. I was slowly losing coolant with no discernable leak.

I just got this done and Audi quoted me $2500 for just the thermostat. Mine was covered by the extended warranty Audi has on all water pumps leaks.

the 80c has been running flawless. Only difference is that my coolant stays at 83-94c. It used to get as high as 100 sometimes. Also the 80c part was recommended oe part #

Been running the 80 for a month or so. It works great. Car and Temps run flawlessly. Only difference is my average warmed up Temps are 85c. Used to be 95c

I finally got around to installing a new thermostat/o-ring/housing and coolant reservoir/cap yesterday. When removing the thermostat, I noticed that the bottom bolt was VERY loose... I had done the thermostat without housing about a year ago now, had never leaked coolant before... My best guess is that I just didn't torque it enough and it slowly loosened, but only when cold (just a guess, but would help explain why no drips when car was running on ramps) and in small enough amounts that I did not notice a puddle on the ground.

My Q5 with 75,000 miles on it developed a leak in the water pump area. Initially Audi denied there was a leak, so I took pictures and showed it to them. Then they diagnosed it with thermostat leak.

I replaced the thermostat from a non-OEM to Motorcraft about a month ago, and the only difference has been the speed at which the dial moves from higher temps to its normal positon.

The current plastic thermostat looks a little more beefy, but is still shatty plastic. They're commonly failing at 30-55k miles in the stuck closed position, instant overheat.