HELP! 1.8 turbo 2005 Passat engine sludged and dealer denies warranty!!
 

I bought my girl a used 2005 Passat with a 1.8 turbo 4cyl/automatic which only had 51k miles on it.The car looks great and seemed to run good for the past 1k miles. Now the oil light is coming on and the dealer says the engine is sludged up. The pulled the valve cover and showed me that it looked like a barbeque in there. They first told methey wont warranty it unlessI give them oil change records. The previous owner gave me about 5 records, which I forwarded to the dealer. They still refuse to honor the warranty because theFirestone where the previous ownerhad the only changed at used a Synthetic blend which is half synthetic and half dino oil. The dealer insists that Volkswagon says to use full synthetic only in the 1.8 turbo. My problem is I dont have the original owners manual which I suppose could make or break me. The dealer cant provide any information to me showing anything that states full synthetic oil.
Can any of you guys help me out?? The dealer wants almost $3k to fix this car. The payments are already killing us.
All I need is a scan of the page in the owners manual showing what type of oil is to be used and/or a tsb from Volkswagen stating that the 1.8 turbo requires Synthetic only.
Any help would be GREATLY appreciated. TIA