I recently brought my 08 automatic to Service Pro (Fast Lube) for an oil change. I asked for synthetic, as my understanding was that the life was twice as long as regular oil. The garage used 530SYN, but indicated that I should change my oil again just 5K miles later. This is the same interval as regular oil. Does this make sense to anyone? Should I be good to go for 8-10K daily driver miles with synthetic?