Quote Originally Posted by Lucas_R View Post
Same engine but in the Mk5 they are much more reliable. When they were put in the Mk6 (and Polo GTI) they were tuned to run very lean (use less fuel) which makes them run very hot, and the pistons were bad quality - eventually the pistons will crack or burn a hole in a piston which requires a rebuild.

Use 98 octane fuel (good quality from BP or Shell etc - not no-name service stations), keep the oil fresh and you should be ok.

Regarding the tune, most places wont tune these anymore due to the reliability issues. The DSG in the Mk6 is equally as bad (7 speed dry clutch), but im not sure if the Mk5 GT had this same version of the DSG.
You’re right about the fuel quality. We use only BP in our 118TSI. The engine oil and filter gets changed every 6 month and I always put 2.9L of oil with 0.7L of Morey’s Oil Stabiliser. So far so good. The Golf is 9years old now.