Long life on an engine has more to do with staying on the rich side and operating in a clean environment than RPM. If anything, low RPM is harder on the engine than higher. If you insist on lower RPM operation, use additional oil. Low RPM operation also makes the needle setting much more critical.

jeffie8696,
First off, sorry for jumping in on your thread. I am still pretty new to this hobby, and trying to learn as moch as possible, mostly from reading alot on here.
HighPlains,
Can you please explain why low RPM operation is harder on an engine? Does it hurt the engine to fly around at half or even lower throttle? I like to do a few touch and goes, and also practice flying low and slow. Please believe me, I am not second guessing you at all. Just trying to learn, and I have never heard that before. I have two OS 46s, and run them on the rich side, put I too am starting to experiment with different props. Was planning on a max of about 12 to 13,000 rpm on those, but sounds like that might be too high?
Thanks,
Pete