I agree with Don on the longevity issue. The operator's technique can literally make or break the transmission. I trashed the transaxle in my old Yenko by dropping the clutch at 5K with racing tires mounted. It twisted the input shaft of the tranny right in half. I took a furious ribbing from the car club about it until the mechanic called me and said the repair would take a few days longer than he planned. Seems he was testing his rebuild and twisted the new input shaft in half. Fortunately, he was a club member also.Don said:I very much doubt synthetic oil is going to make any difference.