Brake fluids, which type for street and strip?

I'm confused on which type, 3,4, or 5 brake fluid to use on my street and strip cars
I've heard and seen comments to NOT use type 5 on these cars, I'm wondering why
All help appreciated

I use 4 on everything, it’s compatible with 3, and has a higher boiling point. Don’t have to consider the DOT 5 considerations.

Same here, I use Dot 4 in my cars. It is what most OEM cars use now.

I started using DOT5 well over 25 years ago. Primarily to save the paint on my restorations. I always get the stuff all over everything. DOT 5 does not hurt the paint, and I have certainly got enough of it on the paint to know. I have never had any problems out of 5 and I use it in all my old Mopars. But if the problems with paint on the 3 and 4 isn't an issue for you, then there is no real reason to due the changeover, in my opinion.

If it's a real track car, then check out DOT5.1 fluid. We use Motul brand in our endurance racing track car. Basically, the higher the number, the higher the boiling point. DOT is silicone based, but DOT5.1 is the same chemical type as DOT3 and 4, so you can mix them if you wish.

I agree

I have heard that using synthetic brake fluid in systems that don't require it might be harmful to the rubber seals inside the system. Any truth to that? I recently had a master cylinder cap with the rubber expanded so much I could barely get the cap on the master cylinder. I flushed the system and replaced the master cylinder and put DOT 3 back in out of precaution since I wasn't sure if what I heard was true. This was in a 99 Durango 5.9L

This a drag race car that will be ran at our local 1/8 mile track to see if the owner likes drag racing or not. It might run 120.+ MPH in the 1/8, we will see
I do not know anything about that motor, I may offer to make 1 or 2 passes in the car to make sure it goes straight and stops before advising him to go WOT in it
I will suggest that he tries a couple of part throttle launches and lifting at half track and go from there. If he likes it and wants to go for it I'll advise him to foot brake launching it at different RPM before switching to trans brake launching it later at WOT