Guys, since a 911 is really "oil cooled" to a certain extent, I would think you would want to stick to what the owners manual says, and not experiment with going to a thinner product. Also, and I think this is VERY important to know, a given designation like 20W50 says nothing about whether it is a mineral oil or a synthetic, and oils with this same 20W50 designation will differ GREATLY in many ways if you compare one that is synthetic, to one that is not.
Therefore since we can buy a 20W50 in a mineral oil and a synthetic, what is the basic difference you ask? Well, you may be surprised to know a synthetic like AMSOIL 20W50 will cold flow down to colder temperatures than some 10-weight mineral oils will, simply because synthetic is an engineered product with all molecules the same general size, while mineral oil has clumps of differing sizes of molecules. Synthetic will also provide better heat resistance, better lubrication, and LOWER RUNNING TEMPERATURE due to lower frictiion.
I'm a water cooled guy visiting the 911 board because I'm in the market for a 1973 911 for my collection. I'm on the hunt. I don't know all that much about the 911 except that it puts very big demands on oil. Therefore I would think all 911 owners would be using a synthetic.
Here is a link you may find of interest. I posted it on another thread, but I want to share it with everyone so I want to post it here too. It may be buried in the other thread.
http://www.network54.com/Forum/message?forumid=426130&messageid=1125341697
You will note, at the end of this thread I provide a scan of the owners manual for my 928. It stipulates a 20W50 for that particular car over a specific temp range. It does not stipulate a synthetic over a mineral oil. Since I've done considerable research on oil for my various cars, clubs, boats, etc., and since I also know what my oil pressure gauges are reading, I highly recommend going to synthetic for anyone who wants to keep good equipment in good condition.
Sincerely,
P
Anyone out there with a 1973 911 or similar model for sale, send me a note !