hi, i just called my local audidealer and they told me that they sell the 5w 30 non synthetic...is this the right one....i'm at 40,000 miles and was wondering if i got the right one...i got "Mobil 1" regular....5w 30 will this one be ok???

and one more thing...whats the difference between non/semi/fully synthetic oil...

thanks for your help!!!

forgot to say....it's a 2002 B5 chasis S4

 

Check your owners manual for oil weight. Or you could go onto Mobil or Castrol website and find the correct oil.
You should definitely use full synthetic oil, and make sure it meets VW 502.00/505.00/503.01 specifications. It will state them on the bottle
Mobil 1 full synthetic 0W-40

 

5w 30 is perfect run on full synthentic thou. You will be alot happier and so will your motor.