Fool may be a bit strong - naive maybe. What the loacal chain dealership will tell you about what repairs your car needs, as I have found with my VX dealer, depnds as much on their current up-selling policy as anything else, in the same way as the car sales quotas/time of mnth/quarter etc. can affect the price you will pay for a car
Don't know where I can get oil in bulk do you? - I have 3 family cars now to service, each of which has an oil change every 6 months