Mostly as you can tell i just read and enjoy all of your informative posts but thought i should check with you guys before i make a purchase. My 38cc Lowes poulan has quit on me so i called the Dolmar dealer about 12 miles away to ask about the 5100. He said it is the 5105 now but didn't have any in stock. He did have the 510 and said that would be the way i should go. When i mentioned that the 5105 had 3.9 hp vs 510's 3.3, he said not to go by that but to focus on the cc's which are the same. He also said that you have to be really exact when mixing oil and gas so as to not to damage your engine due to the high rpm's at 14,500. He cautioned me about ethanol in the gas as well causing a hotter engine leading to damage. He did say that he would order me one but he really thought i should go with the 510 and a 3/8" chain for cutting firewood. I felt like he was sincere but was he really trying to unstock a 510? BTW, he quoted me $495 for the 5105 and $415 for the 510. Thanks for any advice.