Brought it in yesterday for the 10K service and had them use Mobil 1 15W-50. The car is not yet chipped but I plan on chipping very soon. I think I've decided on the MTM/Hoppen Stage 1+ setup, which includes the MTM stainless steel muffler w/twin, 70mm tailpipes. This combo(chip+muffler) brings the horses from 150 to 193 and the torque from 155 to 232. I also plan on installing a K&N panel air filter at that time. Do you think the 15W-50 weight is best for this combo and the Connecticut climate(pretty hot, humid summers)? I usually drive relatively hard, as my tach hits AT LEAST 4K RPM every time I drive it.<p>JT '99 1.8Tqms A!, soon to be "xenoned" <br>

I had 15W-50 in the car after 5K service and chipped soon. I am in Houston, very hot all year long. <p>After visiting redlineoil.com, at 10K service I switched to 10W-40, even though the summer is coming. Reason: synthetics are in a class by themselves, the numbers do not really reflect the improvement over dino oil. E.g. redline 10W-40 is better at any temp than a 20W-50 dino oil. <p>In your climate your best bet may be redline 10W-30. On the other hand the only disadvantage you may experience w/ Mobil 1 15W-50 is slightly slower turbo spool-up. It really does not matter as long as you are using a good synthetic. <p>Interestingly, redline states 10W-30 is the best oil if your primary concern is longevity. <p>No flames please...

I just had my 10K service 2 days ago and also switched to Mobil 1, but I chose 10w30... I am in NY and have used it on prevoius cars with no problems... Just got chipped today with APR stage 2, and car is totally changed... No problems with synthetic and my setup...<p>DMak 1.8TQMS

Ha!! I'm running Amsoil 0W/30 series 2000 in South Florida. I don't think you have much to worry about. If I were you I would use the Amsoil 0W/30. Best oil on the market. I think mobil makes a 0W/30 now. You can't compare the new sythetic oil weights with conventional. Conventional oil relies on film stregnth for protection. The film stregnth comes from the viscosity. Not so with synthetics.