Dot 3 &4 are Glycol based & absorb water. Dot 5 is silicone based and does not absorb water. You state that you are topping off. Do not use Dot 5 to top off brake system with Dot 3 already installed. Actually consider draining & flushing the Brake system & refill with Dot 5.
Dot 3 & 4 also have lower boiling points then Dot 5
Bob
Neither ordinary or extraordinary, just indefatigable.
2000 VX Green Dragon- Chick Demagnitizer-Supercharger-Injen Intake- Cold air box-K&N- Power Vault SS Exhaust-265-75-16 BFG MT kms-On Board CO2- Custom Boulder Bars- Custom Skid plates- PIAA 520 Fog Lites-3inch lift with OME 912 Springs-LINE X Bedliner on Cladding & Hood Insert-ARB Front Lockers & Custom Bull Bar. Vintage Offenhauser Hood scoop Thule Rack. XM Radio-Custom Storage Box-First VX to surmount the RUBICON.Thanks Sierra Stompers