If you are only topping up in between services,say less than half a ltr in a year using 502 this surely would not be enough to dilute or effect the other 4.5 ltrs of oil in the engine ?

, i still can`t get my head around the vw golf gti owners handboook saying to use 502 on non longlife service and this being incorrect

Can anyone say what standard oil all gti mk6`s are filled with when they leave the production line and if it was 502 can you top it up with 504