Outer Limits 4x4 Board

Just wondering if DOT 3 and DOT 4 brake fluids are interchangable? My zook says run DOT 3 only but was this made before DOT 4 was around (87)? The only difference I can find is that 4 has a slightly higher boiling temp. Supercheap only had dot 4 and I need to top up the brake fluid so is it ok to mix with the dot 3 if thats whats in it?

John.

its all the same. Just some chemical difference. One of them is easier on the seals, so i think older cars use dot4 or sumthing . Stopping wise its all similar, and even with the seal thing I dont think its a huge fuss

As long as its not silicone based, yes. You can use DOT4 in DOT3 systems, but not the other way around, if you can find DOT3 fluid anyway.

Nah its not the silicone based DOT 5. I thought it must just be older cars too but both my 87 zook and 2000 pulsar say use DOT 3 only.

I thought that DOT 4 said on the lable somewhere that is compatible for all DOT 4 and DOT 3 appliclations.
Im only going by memory here though.
I know the silicone/synthetic stuff can cause problems but I think you will be right with DOT4.

does it matter if you mix 2 brands,one is a differant colour

4sum4 wrote:does it matter if you mix 2 brands,one is a differant colour

I have never let it worry me but I dunno if it is a bad thing.
But its a good excuse to give it a good bleed and flush some fresh stuff through anyway

I just had a look at the bottle of DOT4 penrite I have in the shed and it states on the bottle "suitable for all Super DOT4, DOT4 and DOT3"

4sum4 wrote:does it matter if you mix 2 brands,one is a differant colour

Nah, you will be sweet.

i use the ferodo dot4 which is good for dot3, it gose into the 88 GQ patrol pulled me up everytime no dramas

Same as Auto Trans fluid and such

My GQ patrol Transfer case says to use Dexron II Auto fluid in it but i use Dex 3,

Its the seals etc, if you use a dot4 fluid in a dot3 system you can have alot of problems with your seals deteriorating. However its likely that all your brake components have been serviced, in which case they are likely dot4 compliant anyway.

Having said that, I dont think I have ever found a dot4 fluid that isnt dot3 compatible, so perhaps when dot4 first came out it was different enough to cause problems, but the newer style is cross compatable.

4sum4 wrote:does it matter if you mix 2 brands,one is a differant colour

Unfotunately if one is blue and one is yellow the fluid will turn GREEN.

Bazzle