Im sure thats dealer price i only paid for the premium membership, i think with the 25% off my cost is around the $43-$44 range for the more expensive signature series. Amsoils recommended oil change interval is iirc 25k miles for normal use and 10k for heavy use. I changed mine every 10k with a filter change at 5k. That was in my pathfinder i only have around 100 miles on my gp and ive changed it 2x first was break in oil and now regular.