Dot 3 v Dot 4

[Deleted member 13129]

Hi every one
I was wondering what is your opinion on using Dot 4 brake fluid instead of the recommended Dot 3 .
I have heard that using Dot 4 can affect the seals in the piston calipers , about a year ago I removed as much fluid as I safely could from the reservoir about half , then filled it up with a brand called commer synthetic Dot 4, its specified sae j1703 , FMVSS,116 , as the toyota handbook states to use , I had a mot last week and was advised that the drivers side front brakes which is nearest to the brake res was slightly less than the passenger side not enough to fail the test but it showed a difference . Has any one had problems with using Dot 4 .

 

[AndyCook]

I am sure Julian posted something once on his overland cruisers Facebook page about Dot 4 causing seal problems

I have just replaced front callipers on my 5 year old Hilux
The brake pistons were repeatedly seizing, and there was minor corrosion
On the pistons
This hilux has had dot 4 brake fluid in system in the past

The brake master reservoir states Dot 3 only on the lid
But I am sure the owners handbook says dot 3 or dot 4

When I fitted new callipers to my hilux in July, I flushed out brake fluid and used dot 3 when refilling

 

[Towpack]

My understanding is that a Dot 3 can be replaced with Dot 4 but you can’t (or shouldn’t) use Dot 3 in a system specifying Dot 4. Additionally you can’t use Dot 5 in a system that’s used either 3 or 4 without a strip and flush of all braking components despite Dot 5 offering superior performance.

 

[flint]

+1 Apparently, Dot 4 tends to absorb more water than Dot 3, but has a higher boiling point.

 

[uHu]

Dot 5.1, Toyota brand. Beats them all, better than 3 or 4. Compatible with everything Toyota made. It's more about which additives are used than whether it's 3, 4 or 5.1.
I other words, the Toyota Dot 5.1 is the only thing you need in a Toyota from a year after the Dot 3 came around.
(Not to be confused with the dot 5.0 silicone not-compatible-with-anything)