[Jazzbass]

Originally Posted by 88carrera

Should I go with 40 weight in the summer, or is 20w-50 ok for all year?

Summer is when you need the high viscosity oil the most because of the higher temps - they have more of a tendency to break down your oil. You could run 10W-40 in the winter, but in an 3.2 Carrera I'd run 20W-50 in the summer.

Keep in mind - newer Porsches (996+ and 986+) are water cooled. The oil is just a lubricant. In our cars, oil is (with air) the main way the engine is cooled. Running the right thickness of oil is much more important than for the newer cars - apples and oranges, so they say.

[GoThingNC]

My brother has been running Castol 20w/50 year round for the last 12 years.

Still sqyueaky clean inside.

He only drives the Carrera 2,500 miles per year and feels that with the Synthetics the cams will be dry after sitting for a week or two which will result in excess wear due to dry starts.
Dino oils doesn't drain off as fast.

John

[Vicegrip]

Another thing to keep in mind is higher pressures at the oil pressure sender does not mean more or enough oil to the far reaches of the motor. When things start to get loose or a oil pump is getting sloppy and the pressures drop, going thicker might only reduce the oil being fed to the ends of the cams or sprayed to the backs of the pistons. I like M1 myself. one thing is that it does not coke up like dino and the insides of the motor stay cleaner.

There is a motor over at Audi that I am going to take a picture of and post here. A real horror story of "lets just see what not changing you dino oil for a real long time" looks like.

The oil guy that came up with the mentioned rating method is a bit thick himself.

John you brother might to look into thin fillm shear strenght and bond adhesion. Acording to the info I have gathered this is primarly what protects on startup. The work is being done at startup by an almost invisable film. High mol level shear strenght is key and the synthetics are measurably hands down better than dino. One place that some might find wear from synth not seen in dino is high reving motors with high lobe cams. Talking pure race, not anything streetable. In this case the ultra grade race spec dino oils look to be better than synththetics.

[Mike W]

Originally Posted by TD in DC

Although for a water pumper poseur porsche, my engine rebuilder urged me to use Mobile One 15w50 for the race car.

That's what I run in the 911 and (I think) the 944 all year long.