I used to have a 2006 MINI Cooper that overheated on me within 1 year of buying the car. At that time they replaced the thermostat and that resolved the issue.

Now I bought a 2011 MINI Cooper S. The dealer had to replace the battery because it was dead, and they also thought it was causing the check engine light to turn on. After replacing the battery, the check engine light still came on and the car began to overheat. I told them to check the thermostat since I had experienced problems with that in my previous MINI. I'm waiting for the results now.

So it appears that 5 years later MINI is still having overheating issues. I researched online and found that MANY people were having problems with their thermostat and overheating in general, especially with S models.

My first question:

Is there an aftermarket thermostat that is good enough to permanently resolve this problem? (if that's even what's causing the overheating in this scenario)

A friend of mine said it would be a good idea to replace the oil cooler with an after market one. So my next 3 questions are:

Which oil cooler is best suited for a stock 2011 Cooper S?

What is the "perfect" temperature for the car to run at so that it does not experience any problems?

What other parts could I replace (without voiding the warranty) so that the car is less likely to run into temperature problems?

 

I've had my mini since 05 and never had any overheat trouble and still running the original therrmostat .. I have no idea why you have had 2 cars with the same trouble you don't list where you live so can't say it's where you are at ...
have they checked the electric fans ? Air in system?

An Aftermarket oil cooler can help with high oil temps but likely will not change operating temp more then a few degrees

 

They confirmed today that it was indeed the thermostat....lol.....and i haven't even driven the car off the lot!

Anyways, they checked the car for everything else and all seems good. Do you have any idea what is the "perfect" temperature for the car to run at so that it does not experience any temperature related problems?

 

I noticed that when I shut off my car, the fan still stays on. Is this normal?

 

Yes it cools the radiator for a period depending on temp