I am going to be changing my brake fluid in my dot 3 system, and I want to upgrade to dot 4 fluid. any problems doing this as far as damage to system?

 

Not that I know of, the valvoline I used said DOT 3 and 4 on the bottle.

 

Dot 4 exceeds specs of dot 3, so dot 4 is better! nice easy upgrade...mixing is not a problem, but if your old fluid is really bad maybe a flush would be better than mixing bad/new.

 

What he said.
I've just done this last month and flushed the whole system with Dot4 when I put new calipers on my 03 QC Hemi.
No problems with this upgrade.
Remember, bleed the system starting with the rear caliper furthest away from the master cylinder and work forward, ie: Rear passenger-rear driver-front passenger-front driver.
Al.

 

Agreed. I flushed and bled mine a few months back also and I believe it helped. I used slightly over a quart to flush everything