Took X5 4.4 to dealership to replace tires. While there I was told my car was left idleing and they noticed I(meaning my X5) was a smoker. I was told that my size engine was know to have smoke when the valve stem seals needed to be replaced. I was also told this could run anywhere from $3000-$7000. This sounds rediculous to me, but I was wondering if anyone else has had this problem. I often see very light smoke, but I do smell the fumes. What is my problem? Thanks in advance!!!