Bleeding master cylinder in the car

When I replaced my master cylinder I was advised by a mechanic and a couple of other people to stay with the fluid originally used with the braking system. Their reasoning was the brake components were designed to work with it. I was ready to go to DOT5 as well. I was on the fence about it but decided to stick with DOT3 for my car and everything is fine. My car still has standard drum braking.

This issue is similar to the dino oil versus synthetic oil debate. There might not be a wrong answer here.