[turbohead7]

Not true at all, Aaron M. Not all fake synthetic oil is labeled semi-synthetic. Let's just say I have the inside scoop from a higher-up @ Mobil 1 Manufacturing who has absolutely no gain in lying to me. I just thought I'd pass this seldom heard bit of information on to anyone who might read my post. You wouldn't believe the crap certain oil big-wigs are putting in bottles and selling to you as "synthetic" at $6.00/qt. But hey, use whatever oil you want; but don't think that just because the bottle says "synthetic" that that's what you're getting. My statement about older engines in no way advised using thicker oil in older engines in need of mechanical repair. I'm not one who believes in the old "Rings-in-a-Can" fix. The bottom line is, if your 1979 911 engine already leaks, 10w-30 synthetic won't do you any favors. And if your 1983 944 has 47,000 miles on all original gaskets with no leaks, 5w-30 Mobil 1 will find some place to sneak out. You see, Mobil 1 synthetic is naturally more "slippery" or "sneaky". This can be a double-edged sword making it an excellent lubricant; but sometimes "finding" leaks that a petroleum based oil of the same weight would not. Now you see why thicker synthetic oil should be used in older engines: It can prevent leaks which have not started yet. There is no oil on the market that can "mask" mechanical wear, and if there was I would not reccomend it to anyone. Also, not all 944 owners use the reccomended weight. People make their own blends, racers change viscosity based on track and temperature conditions, and Porsche has approved Mobil1 synthetic 0w oil for just about any Porsche ever made. I get the zero weight stuff for free and use it exclusively in all my cars. I have some old leaks and some new ones, some I fix and some I live with. But the cars love the stuff and who could say no to FREE Mobil 1? 20w-50 is plenty thick for any car, my advice is for all cars, not just 944's.