sorry to say, i think richard is right. in my experience with diesels, white smoke is bad. it means coolant in the combustion chambers. unburned fuel is black smoke, blue smoke is burned oil. the coating on your back window might be coolant after its been through the exhaust after burning. check your oil. does it look normal, or does it look kinda like chocolate milk? if its milky, there's coolant in there.that means head gasket, or cracked block or head. have you had trouble getting heat from your cabin heater? that's a sign your head gasket is going bad. coolant is going into the block, but not into the heater core for cabin heat. if either of these signs are there, you have a big problem.either way, don't drive until you get it looked at.