Air-cooled 911 oil choice,what are people running?
There's an endless debate about oil for air-cooled 911s. The engine runs hot and the oil does a lot of work cooling as well as lubricating. I've been running Motul 300V 15W-50 but some people say that's too thick for the SC engine. The factory spec is 20W-50 mineral oil but that was written in the 1970s. What are SC owners running in the Australian climate? I do about 8,000km per year with two or three track days.
Motul 300V 15W-50 is a good choice for mixed road and track use. It has the high-temperature film strength that an air-cooled engine needs and the 15W cold pour is fine for Australian temperatures. The factory spec of 20W-50 was for mineral oil, and a modern 15W-50 synthetic is better in every measurable way. I run the same oil in the S14 M3 engine for similar reasons. Don't go thinner than 15W-50 for an air-cooled engine that sees track use.
For my 356 I use Penrite HPR 30 which is a 20W-60. These older air-cooled engines have larger bearing clearances than the SC and need the thicker oil. However, the SC has tighter tolerances and the 15W-50 is perfectly appropriate. The key is to change it frequently, every 5,000km or after every track day, whichever comes first. Oil is cheap. Engines are not.
I run Motul 300V 10W-40 in my 944 Turbo but that's a water-cooled engine so different requirements. For air-cooled I'd stick with 15W-50. The consensus in the Porsche Club of NSW seems to be that Motul 300V or Penrite HPR 10 in 15W-50 are the two best options for the SC. Both have proven track records.