I've owned five planes with small Lycomings and Continentals. I fully
agree with what the others have said. Leaning on the ground and in the
air, burning mostly auto gas, and using MMO is the way to go. But I'll
add one more -- FLY REGULARLY! Try to not let that engine sit idle for
more than three or four days if you can. The engines that last the
longest are the ones that are run just about every day.

- Brett