All polyethylene glycol based fluids will not harm healthy rubber parts.
Dot 4 brake fluid rubber compatibility.
Even an older rubber part with a high concentration of natural rubber will not be damaged by new dot rated brake.
All steel lines.
Dot 5 is a silicone fluid.
I do not know what types of rubber are in the rover brake system but i doubt it has silicone or fluorosilicone.
Dot 4 absorbs less moisture than the dot 3 fluid and many enthusiasts have converted their hydraulic brake systems from dot 3 or dot 4 for this reason.
Since dot 4 and 5 1 are both glycol based brake fluids they are compatible with each other which means they can be readily mixed without harming your brake system.
Changing the fluid is not all that is involved in this conversion though.
This page contains a guide to selecting o ring materials based on chemical compatibility requirements.
The types of rubber not recommended for use with silicone fluids are silicone rubber and fluorosilicone rubber.
Like you were taught in high school chemistry regarding solubility like dissolves like.
Brake fluid manufacturers can and often do improve on these figures and it is possible to find dot 4 brake fluid with a higher boiling point than some dot 5 1 fluids on the market.
Dot 5 brake fluid is silicone meaning it doesn t absorb water.
It s not compatible with the other brake fluids and is used mostly in classic cars that remain in storage for long periods and need a.
The chemical compatibility data can be presented in one of two ways.
First you can select a specific o ring material to view its compatible chemicals.
For a faster reaction of the abs and esp systems dot 4 and dot 5 1 brake fluids exist with low viscosity meeting the maximum 750 mm 2 s viscosity at 40 c f requirement of iso 4925.
All dot 3 4 and 5 1 brake fluids are compatible with each other and with all systems all polyethylene glycol based fluids will not harm healthy rubber parts.
Both dot 3 4 and dot 5 fluids are compatible with most brake system materials except in the case some silicone rubber external components such as caliper piston boots which are attacked by silicon fluids and greases.
To prevent cross contamination you should also change all the rubber components in the brake system.
Or second you can select a specific chemical to view all its compatible o ring materials.
Dot 5 1 is used in high performance and heavy duty applications due to its high boiling point.
It s compatible with dot 3 and dot 4 fluid.
Dot 5 1 fluids are specified with low viscosity over a wide range of temperatures although not all cars fitted with abs or esp specify dot 5 1 brake fluid.
Even an older rubber part with a high concentration of natural rubber will not be damaged by new dot rated brake fluids.
