hello hope you can help, got white smoke coming out of exhaust not too thick would it be down to having white stuff in air filter breather pipe, cleaned out most of it and put new air filter in as the other one was oily also when i bought the car the coolant was very watery and slightly brown (think they just put water in there) and it doesnt seem to be loosing liquid , if it was a head gasket problem how much coolant would you be loosing over say 10 mile journey ?