First of all, if I were you, given the sitution you describe, I’d check the fluid levels daily.
Second, you need a mechanic you can trust to do right by you.
Think about it. You can go to Walmart or Target or your bank, and they’ll usually do right by you. Why? Because they need repeat business to thrive. If they do a bad job, you won’t come back. And worse, you’ll tell other people you know what happened, and they won’t go there either. Walmart, Target, and yoru bank relies on customer good will to thrive.
Mechanics sometimes don’t think of repeat business as a motivating factor. They’ll do a well-done repair, and never see the customer again. They’ll do a badly-done repair, and never see the customer again. There’s no feedback mechanism.
So I think that’s what you need to develop is a MFM (mechanic feedback mechanism). The way you get it is to seek outpotential mechanic opinions from your friends, neighbors co-workers, church goers, anybody you have a personal relationship with. Then visit some of those mechanics, see how much experience they have working on your make/model, and then tell the one you decide upon that the reason you are going to them is because “John Schmidt” or whoever it is, a current customer of theirs, recommended them to you.
Then your new mechanic will have incentive to do good by you. Because if he doesn’t, you’ll tell John Schmidt what happened, and not only will the mechanic loose you as a customer, he’ll likely also loose John Schmidt.
At some point you either have to do it yourself, or trust your mechanic. Hope that may be of some help.