I have the same car however I have no mods. I bought it used with 5,000 miles two years ago...it now has just over 10,000. First summer I used Mobil 1 5w-30, last summer I used Mobil 1 EP 5w-20, and this year I have tried Amsoil XL 5w-20. Drove it for the first time this weekend and the engine is noticeably quieter with the Amsoil than it was with Mobil 1. I will probably switch to PP next change and do it every six months no matter how many miles were driven. The general consensus from what I have read is stick with 5w-20 with the mach.