I have a 1982 300D, 231,000 miles and was thinking about putting Mobil One synthetic oil (red cap) into the engine. (where else would I put it?) Anyway, I have a mechanic friend who uses it in his 1976 300D and swears it's better than anything he's ever used. I have friends who say "be careful" etc. and obviously don't think it's a good idea. I would appreciate any "pros" and "cons" regarding this matter. Thanks.