DOT3 or DOT4 fluid

[Heath]

Have to do a fbrake fluid change soon and found a bottle of DOT4 fluid. only thing is my manual says DOT3.

Can I use DOT 4 in a vitara (early 90's model)

Cheers

[KiwiBacon]

Yes, they're completely interchangable.

[tallsam66]

If its an old bottle you have found in your garage DONT use it.
Brake fluid is hydroscopic & it absorbs moisture from the air.
Youd be better off to buy some new fluid & use that .

[TJ]

You can use a Dot 4 fluid in a Dot 3 system (with some fluid left over). Its not recommended the other way around.

Also, try to use fresh fluid. If its been sitting some time, its not likely to be too useful.

[Heath]

Cheers. The seal is intact, so I figured if it was compatible in it goes.

Cheers,

Heath

[Dr_PC]

Whats wrong with Fresh DOT 5 I say

[Heath]

I have a nice sealed bottle of vintage dot 4 (circa 06) in my garage. Would be a shame to not use it.

I am on a budget after all.

[KiwiBacon]

Whats wrong with Fresh DOT 5 I say

DOT5 is silicone based. DOT 5.1 is compatible with DOT3 & 4.

[Dr_PC]

I have a nice sealed bottle of vintage dot 4 (circa 06) in my garage. Would be a shame to not use it.

I am on a budget after all.

Okay I forgot Sorrryyyyyy

[Dr_PC]

DOT5 is silicone based. DOT 5.1 is compatible with DOT3 & 4.

I tend to totally replace my fluid rather than topping it up. Do this every couple of years

[Heath]

Yeah I'll be dropping the fluid out and doing a complete change. Only way to have confidence in your car is to do it all and do it right.

So what is the big deal with the silicon? Does it raise the boiling point?

[Sadam_Husain]

I remember getting caught out in my old FJ45 a few years back when I ripped a brake line out in the scrub and I used a bottle of meths to replace the brake fluid once we got a pair of vice grips locked onto the rear brake hose to get me back home. I dunno what DOT rateing the meths was but it worked ok and eventually I drained it all out and put some new brake fluid back in and it all seemed ok?

[Dr_PC]

Yeah I'll be dropping the fluid out and doing a complete change. Only way to have confidence in your car is to do it all and do it right.

So what is the big deal with the silicon? Does it raise the boiling point?

Yes

[KiwiBacon]

So what is the big deal with the silicon? Does it raise the boiling point?

No it doesn't, good DOT4's and all DOT 5.1's have higher boiling points than DOT 5 silicone fluid. They're also cheaper, easier to find and not as spongey.

[Dr_PC]

No it doesn't, good DOT4's and all DOT 5.1's have higher boiling points than DOT 5 silicone fluid. They're also cheaper, easier to find and not as spongey.

DOT 3 401ºF Wet boiling Point 284º F
DOT 4 446º F 311º F
DOT 5 500º F 356º F
DOT 5.1 518º F 375º F

Silicone-based fluids are regarded as DOT 5 fluids. They are highly compressible and can give the driver a feeling of a spongy pedal. The higher the brake system temperature the more the compressibility of the fluid and this increases the feeling of a spongy pedal.

As I mentioned in my earlier post I tend to chmage my fluid every 1 to 2 years so I dont have problems with Silicon type fluids not mixing with water like standard type fuilds, and my brakes never get hot enough so I dont have that spongy pedal type feel.

When i was doing sppedway I use to use AFCO 570 degree fluid from the states but as the wet boiling point didnt meet the Yanke federal specs it was graded as DOT 3 but the dry boiling point was higher than DOT5.1

Depends on what you do with it and what you use it for

[KiwiBacon]

No it doesn't, good DOT4's and all DOT 5.1's have higher boiling points than DOT 5 silicone fluid. They're also cheaper, easier to find and not as spongey.

DOT 3 401ºF Wet boiling Point 284º F
DOT 4 446º F 311º F
DOT 5 500º F 356º F
DOT 5.1 518º F 375º F

Silicone-based fluids are regarded as DOT 5 fluids. They are highly compressible and can give the driver a feeling of a spongy pedal. The higher the brake system temperature the more the compressibility of the fluid and this increases the feeling of a spongy pedal.

As I mentioned in my earlier post I tend to chmage my fluid every 1 to 2 years so I dont have problems with Silicon type fluids not mixing with water like standard type fuilds, and my brakes never get hot enough so I dont have that spongy pedal type feel.

When i was doing sppedway I use to use AFCO 570 degree fluid from the states but as the wet boiling point didnt meet the Yanke federal specs it was graded as DOT 3 but the dry boiling point was higher than DOT5.1

Depends on what you do with it and what you use it for

I just had a read of the bottles in my garage. None of them list a boiling point but stuff I've had in the past did.
I've got a bottle of Nulon Super DOT 4 which according to their datasheet is 286C/184C dry/wet which is 547F/363F, about the same as the DOT 5 silicons.
http://www.nulon.com.au/facts/Factsheet%20112.PDF

I know a few motorsport guys who swear by this motul stuff which is 312C/216C which is 594F/421F.
http://www.motul.com.au/product_line_up ... ers04.html
I don't need anything that boils that high, my pads would be molten long before then.

[Dr_PC]

I know a few motorsport guys

Just have to remember when using racing type fluids they need and must have regular changing. Racing engine oils had to be changed after every race meet. They are designed for a purpose however the life of them is dramatically reduced. I do like the look of the Motul 660 tho

Sorry about the sort of thread hijack Heath Use any type of fluid just make sure that you COMPLETLEY replace all the fluid in the lines