DOT-3 Vs. DOT-4

[jldiaz]

Can anybody tell us the difference between DOT3 and DOT4 brake fluids? Can they be mixed?
Thanks.

[egon]

You can mix them, but its better to flush out the DOT3 and have only DOT 4 in the system. DOT 4 has a higher boiling temperature then DOT 3.

--Matt

[jldiaz]

OK. Thanks.
Any other issues, like moisture tolerance, etc?

[egon]

Moisture tolerance is about the same I think. Valvoline makes a synthetic DOT 4 brake fluid that has better moisture resistance. I've been using it for awhile, it shows its usefulness when stopping or holding the vehicle when off road.

Some links.

http://www.xs11.com/tips/maintenance/maint1.shtml
http://www.valvoline.com/pages/products/product_detail.asp?product=51

--Matt

[zebulon]

has a effect on the abs. if not used in right systems it wears the o-rings out at accelerated rate. and it can stick valves in some adv. abs systems. best to stick to OEM

[egon]

has a effect on the abs. if not used in right systems it wears the o-rings out at accelerated rate. and it can stick valves in some adv. abs systems. best to stick to OEM

MOPAR provides us (dealers) with DOT 4 Brake & Clutch Fluid P/N 454625AC. It specifies on the bottle "Can be used in place of DOT 3 fluid". DOT 4 is an OEM fluid.

--Matt

[Sterling90XJ]

.
Just like Dexron II and Dexron III... You can upgrade to a higher number, just don't ever go down to a lower one.

.

[jldiaz]

OK. thanks, Guys. I'll be switching from 3 to 4 soon.
Good link, Egon!

[tripletsjeepin]

They have Super Dot 4 also... the difference is that super dot 4 isn't suppose to change color....but it does. Just a tidbit for you

[egon]

4549625AC is the part number for the MOPAR DOT 4 fluid for those that are interested. I just noticed I forgot a digit.

--Matt