Mixing synthetic and non synthetic brake fluid?

Wizardskills

Wizardskills

Wizardskills

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Quick question. Is it OK to mix synthetic and non synthetic brake fluid together? I'm going to be changing the brake pads on my GT6 either today or tomorrow and I haven't touched the brake fluid since I got the car so I don't know what it has in it. With it being the brakes I don't really want to bugger it up for obvious reasons :p.
 
If you are considering using DOT5 where you've had 4.1/5.1 -dont. They dont mix and cause the seals to swell and break.

Silicone and mineral fluids dont mix.
 
TRNC said:
If you are considering using DOT5 where you've had 4.1/5.1 -dont. They dont mix and cause the seals to swell and break.

Silicone and mineral fluids dont mix.
Click to expand...

Whilst this is correct, silicone brake fluid is different to synthetic brake fluid.

Synthetic brake fluid is made from Glycol Ethers and Borate Esters, and, I am fairly sure, can be mixed with non-synthetic brake fluids (in the same way mineral and synthetic engine oils can be mixed).

If in doubt, check the manufacturers website, I am sure it will say.

Carlube dot3 & 4 can certainly mix with other brake fluids, so can Pagid synthetic, although I don't think anything will mix with silicone.
 
Last edited:
Motul Dot 5.1 synthetic datasheet says:

Mixable with DOT 3, DOT 4 and DOT 5.1 NON SILICONE BASE products.
Do not mix with silicone (DOT 5 silicone base) or mineral base fluids (LHM).
Store brake fluid in its original container, tightly closed to prevent absorption of moisture.
Aggressive chemical product if contact with hands, paint or varnish.
If skin contact, rinse thoroughly with water.
Drain interval : 12 to 24 months as per manufacturers’

http://www.opieoils.co.uk/pdfs/MOTUL/DOT-5.1-BrakeFluid8070(GB).pdf
 
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