The Amsoil vs Rotella-T thread got me to wondering. I have crunched the numbers with high dollar synthetics and found that to make them pay on my small farm, I'd have to run them at least 5-6 years in service. I'm running Rotella-T out two years and about 75-80 percent of the rated OCI hours now after great UOAs at over a year in service at about 50 percent of the rated hours. I was intending to test again and maybe try three years. Amsoil people; what you you think... 5-6 years possible?