When I bought my Axys last fall I asked the dealer the same question, he recommended the Red. He said that they had run identical sleds for a season, one on gold and one on red. They then tore both engines down to compare. Both were good, but the one running the red had less wear and less build up. He also said that the red had more protection against hot spots. He's had a lot of experience with sled engines. I'm going to stick with red. Yes, a little more expensive, but not much.