I have a 1985 SAAB 900 Turbo. It has only 80,000 original miles on it. Not too long ago the engine started cutting out, and it began blowing oil out of the dipstick/filler neck. I took it to the mechanic for an opinion. He checked the PCV valve and found excessive back pressure in the top of the engine. Was informed it would require a rebuild or a replacement engine. Does this sound right for only having 80,000 original miles? According to the records that I have the vehicle was maintained well but could have been sitting for a prolonged period of time before I bought it.