They should tell you what they will do, instead of just doing whatever for a tuneup. I didn't need an oil change so soon, but neat that you used synthetic though a bit costly. Be nice to see a printout, of any emission test, electrical output, etc. to see how the car is performing. Maybe show the old coolant. If I asked what you did to the car, be nice if you tell me, instead of having the customer read it off the invoice, maybe the mechanic could take two minutes and say yeah all is good, just changed fluids, didn't notice anything major.