DOT 4 (vs 3) For Older Car

[galaxy]

So yeah, dot 3 and 4 are compatible and interchangeable. Dot 4 higher boiling point (plus), but at the expense of being more hygroscopic (minus). Is there any benefit or real reason to run dot 4 in an older car (2002) that originally called for dot 3? What would you gain, if anything at all, assuming the higher boiling point is not needed? They are slightly different viscosities; is that something you’d ever feel in the pedal?

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[Norm Peterson]

If you don't actually need DOT 4's minimum boiling points, then there isn't enough reason to get DOT 4.

But that doesn't stop you from getting DOT3 fluid with higher than min-spec DOT3 boiling points . . . in fact I'd recommend doing just that (paying attention to wet boiling points in particular).


Norm

 

[1 old racer]

Unless you track it or live up in the mountains, do what Norm said.

 

[Norm Peterson]

They are slightly different viscosities; is that something you’d ever feel in the pedal?

The only thing about brake fluid viscosity that I am aware of is for recent-year cars with stability control that specifically call out the use of "Low Viscosity Brake Fluid".

The reasoning involves LV fluids having better resistance against cavitation happening inside the ABS HCU during ABS/Stability Control interventions.


Norm

 

[DougS550]

I dont know about your year model, but my 2019 Specifically states to use a DOT-4 LV. Make sure if your manual states to use "LV" Brake fluid to use it. Good Luck

 

[galaxy]

It does not say that from ‘02, lol! Thanks guys.

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