In Reply to: Changing over to synthetics posted by Reece on 08/15/01 at 8:05 AM:
Changing from mineral to synthetics does not require flushing. That is if you are using a PAO type - Mobil1 or other name brand synthetic. There are some obscure brands that are not completely compatible and do need a flushing procedure.
Depending on the engine you run, age and climate you will need to determine the following.
Seal compatibility, OEM approval, best viscosity for your engines age, your climate and driving.
OEM approval is only a concern on some exotic engines that need the higher friction of the synthetics to operate properly.