Interesting that some mechanics claim synthetic oil is the greatest thing since instant coffee and others are more wary. My guy claims that if the car is built before synthetics became available, the seals and gaskets will eventually break down as they are not constructed to resist the action of some of the additives. My own attitude is that as my SL is basically a toy car and does very little mileage, using a high quality standard oil is all I need. I change the oil based on time more than distance anyway and typically this works out to between 1,000-1,500 miles. I doubt I'd get any benefit from synthetic oil even if there was no risk factor, and using a good quality mineral oil is way cheaper than a synthetic which is another small bonus. There must be many other SL drivers in the same position.