Last week I got my 87 535is back from a "full service" tune up and I noticed later that night that it was really running rough so I took it back the next day and of course they looked it over and said nothings wrong so three days later I got the idea to check the oil and it was Way to full this has got be the reason for the rough running...how much damage do you think has been done? I really baby this car and this is a highly recommended bmw shop in Portland Or.