T tcc101 New member Mar 6, 2011 #1 I have a mk4 gti with about 117xxx mile. What's the best way to do it? Also, iis it bad to go from regular unleaded to the 91 octane? Or should I gradually switch it?
I have a mk4 gti with about 117xxx mile. What's the best way to do it? Also, iis it bad to go from regular unleaded to the 91 octane? Or should I gradually switch it?
