i have a 2003 vw jetta 1.8 liter turbo. a few weeks ago i got my oil changed at a volkswagen mechanic but i forgot to ask if they used a fully synthetic oil (i didnt want to sound stupid). later looking at the bill i saw he used a synthetic blend for around 25 dollars. am i in trouble? i know conventional oil causes big problems in my type of car and that it calls for fully synthetic. what should i do?