So about 8 mos ago i bought a 2004 A4 1.8t quattro. had a CEL about a day after purchase but went away. Couple months later noticed i had a small coolant leak (thought it was from a hose clamp failing) didnt pay too much attention and kept it topped off. As time passed the Start ups were getting worse and rough and the CEL came back on. Checked the code and it was for a misfire in Cyl. 2. Changed all plugs. CEL came back. Really rough start-up now producing thick whiteish smoke. So i yelled at the dealership enough to look at it for me for free. and same thing Cyl 2 misfire on startup only, and told me to replace my thermostat becuase it was my leak, and the change the coil packs. But siad they found no reason for white smoke. changed coil packs. no coolant or water in oil or vice versa. CEL Came back. bout a month later (not driving the car) ive finally replaced the thermostat, that stopped my coolant leak but i still lost about a liter of coolant. Car is still idleing rough, and now i HAVE found coolant in the oil. CEL is back havent checked the code yet.