I have owned a Golf GT Tdi 170 since new and have covered 5500 miles and have been topping up with Castrol Magnotec (1.25litres used already) with is a VW 505 01 grade oil, anyway I was reading through the handbook today and saw I should be using a longlife oil with a VW 507 00 grade and now im worried I may have damaged the DPF or even the engine could somebody advise me to whether I need to worry as now im thinking of taking the car to VW to get a new oil change done.

Thanks