Bill,
I used to pre-mix my oil & gas back when I was running auto gas (non-ethanol), pumping into a fuel trailer at the nearby gas station. I would pour the required amount of 2-stroke oil into the trailer tank, then add fuel. By the time I was back at the airport it was well mixed. After they started blending all mogas with ethanol, I was forced to go to 100LL as my wing's adhesives are incompatible with alcohol. My wings have a series of baffles, so adequate mixing became a problem. So, I switched to the oil metering pump (OMP), using Richard Sohn's OMP adapter and drawing from an auxiliary tank mounted on the firewall. Now, I just have to remember to keep the oil tank full. I often add a small amount of 2-stroke when filling the tanks, but that is probably overkill.
It is my belief that the OMP puts the oil exactly where it needs to be, directly on the apex seals rather than mixing in with the fuel only to be burned up and blown out the exhaust, most of it never reaching the apex seals. (Probably a topic for future discussion.) Anyway, I'm happy with the OMP approach. It is a very simple pump and has proven effective in millions of RX-7's and RX-8's. The one modification I made was to fabricate steel oil lines to replace the plastic lines.
Mark S.
Lancair ES - 20B - pport