I've got 13,500 miles on my 24 vale. It's time for an oil change and have been thinking about amsoil. I'm going to swtich to synthetic, sooner or later and was just wondering if it was too early to swith it over. I've pulled about 15 different loads with my truck and I think it will be ok to switch over to synthetic now, but i wanted more opinions. Also, what kind of changes can I expect with syntheic? Like fuel mileage and oil change intervals? Thanks in advance for your help.