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