I will give you my 2 cents worth about synthetics. Back in '78' my neighbor bought a new 1086 IH tractor and a couple of months later so did I. He takes very good care of his equipment in every way and he used regular engine oil until it had about 4000 hours and then he went to a popular brand of synthetic oil and still uses the synthetic. I have used regular oil from my dealer for the entire life of my tractor and I pride myself in taking good care of my equipment but he was a little more prompt with his oil changes. At 5000 hours both of us overhauled the engines. The crank and cam were in good shape in both tractors, so piston-sleeves-bearings is all that was needed for the short block with the exeption that he needed a new oil pump and I did not. We both overhauled them again at 10000 hours. His cam was shot and the crank had to be ground and his oil pump was worn beyond specs. My crank was like new with no wear and I estimate the cam had another 5000 hours left in it.(I do my own work) I did replace the oil pump this time. Of course this is a comparison on only two tractors so it is in no way scientific, just an observation. He also uses synthetic hydraulic-transmission oil and he has replaced the TA once. I have always used HY TRAN and I have replaced a hand full of TA's. Both tractors have been used in about the same manner through the years. End of story!