I'm not a PRO but...I switched to synthetic a while ago. No problems with leaks, etc. I now use Mobil 1. 280,000 Kms and going strong. From everything I have learned about using synthetic in an older car it seems the major factors are (Larry can correct me here if I'm wrong) -
1 - Developing leaks from older seals which may not be able to seal properly with synthetic. Basically a small gamble. I had no problems though.
2 - Synthetic 'cleans' up older, hardened oil deposits which can cause leaks, blockage. I think this one is a bit of a stretch, again I've had no problems here.
3 - Once you switch, stay with synthetic. I've heard this confirmed everywhere.
As some people have already stated, if your car is fine with dino, why not keep it that way? I changed due to the extreme temps we get up here - from +30C to -40C and colder in the winter. The main reason for me was that synthetic retains it viscosity at lower temps while dino oil really gets thick and sluggish in colder temps. I have noticed a big difference in winter cold starts with the synthetic.
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired
"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon