Use full Synthetic which meets the 505.01 specs that Volkswagen recommends. The 2006 TDI needs this type oil for proper lube of Turbo. 2004 thru 2006 Pump Deuce engines require this. Did lots of reading on this subject after I purchased my used 2006 TDI. I use Castrol 5w-30 SLX which can only be purchased at a VW Dealer. This is what they put in if you have them do the job. Their are other types of 505.01 oils that can be purchased off the net but why pay shipping when dealer around my area sells the stuff for $7.00 a quart. No cheaper off net and shipping is charged from most places. Book calls for replacement at max of 10,000 miles but I would only push it to 6K or 7K at the max. If you want to go the distance of 10K then replace the oil filter halfway there! Buy a filter off the net for about $6 to $7 dollars. Hope this helps you question.
Your Wrong. Buy it from Walmart. Going to Start Useing "Mobil-1 5w -30 Synthetic Oil" It Cost $ 6.37 Qt. Fram Iol Filter $ 11.94 I've been Useing that "Mobi-1 in my "1996 SVT Mustang COBRA" I change at 10,000 mile's.
Well that might be nice for your COBRA but it does not meet the 505.01 specs and Mobil-1 will not lube a Diesel Turbo with a Pump Deuce fuel delivery system. And by the way mister know it all! Since when did a Mustang COBRA have a diesel engine in it anyway. Let me know if it is still running at 300,000 miles.