I agree with reklund. My 81 had 367,000 miles running penzoil 10w-30 before it needed a rest.

If you check out the Amsoil website they have an oil filtration bypass system that they sell for virtually any engine, even the 22r/re.

Its the deposits that cause the most damage to your engine.

Synthetic can withstand higher temps, and maintain its viscosity longer than conventional, its proven its superior, however may not be necessary in such a low reving, cool running engine such as the 22r.

I say run what you prefer, but change the oil, or atleast the filter every 3,000 miles.

Im an Amsoil guy, but I swithed to Mobile 1 becasue its much easier to come accross locally.     

Oh yeah, not sure if it helps but im running an oversized filter, its a fram tough guard (fram generally sucks) I read the tough guard use a bit better parts than the standard orange filters. To find the larger size I simply opened up boxes comparing the threads, and hole size to the recommended size. Its over twice the size of the stock filter.