we all know the mcs works better in cold climates, but why? when I'm driving for the first half hour the car feels with good response from low revs. but after some time I just feel I'm not driving a car with 170hp anymore.. more likes 140..

outside temp is 89-90º. oil temp for first 30 minutes is between 160 and 170. when the car start to lose power the oil temp is 190-210.
the car is 2006, with no mods.

so.. is the oil temp or the intercooler? I ask this because I want to improve this problem so I don't know if I should buy a bigger intercooler (GP) or an oil cooler.

 

the oil cooler is not needed. you dont want cold oil, it has to be hot enough to burn out impurities.

you do have a problem with heatsoak on your intercooler. another option to look into would be water/meth injection. i'm just coming into mini's, but with VWs everyone did it. i wonder what i don't see it too ofter on the mini.

 

If you want that crisp throttle response all day long, a water-to-air intercooler and methanol/water injection will help you feel like you're running on race gas, primarily by decreasing IATs. There are some good threads on these in the Drivetrain Modifications forum, along with holistic heat management. Some also say that a thermostat that opens at a lower temperature also helps.

 

so is not for the oil temp? is the heat from the supercharger/intercooler?

will the GP intercooler make some improve? I don't want to go on the mods way.. maybe the pulley some day, but I'm trying to stay on the stock/non modified car.

 

It's the relatively small intercooler. A Supercharger makes heat and the IC can only remove so much of it. There is an Intake temperature sensor (IAT) which reads temps at the intake and dials back timing and other power related parameters as a "life Saving" measure...

Power lost to heat is a well documented phenomenom..

 

Many people are going the GP IC route - they're difficult to locate (you may need a GP VIN before the dealer is willing to order one for you) and may be pricey (I've heard something in the order of $800 for one).

Another alternative to look into is something like the Alta Air Diverter for the OEM IC, which will force more air through the IC, with an optional water sprayer.