A dealer recently told me that a 20-1 fuel/oil mixture should be used in all 2 cycle equipment, including Lawn-Boy mowers. He said Japanese manufacturers recommend the 20-1 mix for use in Japan, but EPA regulations have forced the 50-1 mix in the US. He claims the consequence is drastically reduced equipment life, and that the 20-1 mix would double the lifespan of a 2 cycle engine. He also said the 20-1 mix would increase torque under load and improve performance, and that the engine would not smoke after warming up. I watched as he demonstrated and sold a Maruyama trimmer which was filled with the 20-1 mixture. It did smoke a little when first started, but seemed to run very strong without smoking after warmup. I was impressed, and am wondering if anyone else agrees with this?