Syn oils have better cleaning properties except for maybe diesel specific oils and is generally a finer oil.

In my opinion, if you have leaks or just about to, the syn oil will find them for you by cleaning your engine.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)