For me, the choice to NOT do it myself is one of economics. I lose money when I change my own oil; and I lose money everytime I mow my own lawn.
How do I LOSE money? Why wouldn't I SAVE money by doing it myself? Great questions...I will explain:
It's quite easy! I have my own side-business doing web and e-commerce development. For the past 4 years it has sucked up ALL my free time that I let it...last year I worked almost 1000 hours (that is ON TOP OF my FT job).
My hourly rate for that work is high enough that IF instead of doing that work, I change my oil, I lose money.
Same with mowing my lawn.
However, I LIKE to mow my lawn. It is relaxing, and it's a good way to clear my head, so I DO actually mow my lawn, lose that money I could make, and consider it relaxation therapy.
Now, some would say the same about servicing their vehicle, or performing mods...that they "LIKE" to do it and "ENJOY" doing it, and its more of a hobby. To that, I say "GREAT!"
I did my own mulching this spring, because I know "just" how I like it done, but I paid to have the mulch delivered rather than spend half a day carting it in the ST (we needed 11 yards total). And, I have other home projects to do, that I won't pay someone else to do because I need the exercise, and I would probably lose money (net) if I paid someone else to do them.
I guess what I am saying is this...Just don't get too hard on people who take their cars in for service, even for little things. You may feel they are wasting money; but if they are like me then maybe they have learned how to avoid "stepping over dollars to pick up dimes!"
TJR