is dot4 synthetic compatible?

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xpress
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is dot4 synthetic compatible?

Postby xpress » Wed Mar 02, 2011 10:58 am

Hi used shell dot4 I have half litre carlube dot4 synthetic. Same stuff? Or do i need to use mineral based. Is the shell stuff probably synthetic?


Stig
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Re: is dot4 synthetic compatible?

Postby Stig » Wed Mar 02, 2011 4:10 pm

Doesn't it say on the bottle? I know DOT5 silicone fluid says it's compatible with dot4 fluid.

Unless it's special stuff for Rolls-Royce or Citroen then I would have thought it's OK.

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Re: is dot4 synthetic compatible?

Postby Neil MG » Wed Mar 02, 2011 5:21 pm

DOT5 silicon is definitely NOT compatible with DOT4!

But yes it is ok to mix the Carlube DOT4 with the Shell DOT4. No need for mineral based fluid.
1956 Morris Minor Series II
1959 MGA 1600 Roadster
1966 Jaguar Mk2 3.8 MOD

rayofleamington
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Re: is dot4 synthetic compatible?

Postby rayofleamington » Wed Mar 02, 2011 6:05 pm

Neil MG wrote:DOT5 silicon is definitely NOT compatible with DOT4!

But yes it is ok to mix the Carlube DOT4 with the Shell DOT4. No need for mineral based fluid.
Anything mineral is NOT compatible with british car braking systems (or most others too!) and will wreck the seals.
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Re: is dot4 synthetic compatible?

Postby Stig » Thu Mar 03, 2011 7:57 am

Neil MG wrote:DOT5 silicon is definitely NOT compatible with DOT4!
Where do you get that from?

It says on the bottle that DOT5 silicone can be mixed with DOT4 and I've done it with no problems whatsoever.

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Re: is dot4 synthetic compatible?

Postby Neil MG » Thu Mar 03, 2011 8:53 pm

Stig28 wrote:
Neil MG wrote:DOT5 silicon is definitely NOT compatible with DOT4!
Where do you get that from?

It says on the bottle that DOT5 silicone can be mixed with DOT4 and I've done it with no problems whatsoever.
Just poor a little of each into a glass jar and see! Give it a shake!

What exactly does it say on the bottle? Most probably it says that DOT5 is compatible with DOT3/4 brake systems, (not DOT3/4 fluid.)
1956 Morris Minor Series II
1959 MGA 1600 Roadster
1966 Jaguar Mk2 3.8 MOD

les
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Re: is dot4 synthetic compatible?

Postby les » Thu Mar 03, 2011 10:16 pm

I was under the impression that silicon would mix with dot4, but negated the advantages of the silicon. Will have to check on that now!

xpress
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Re: is dot4 synthetic compatible?

Postby xpress » Thu Mar 03, 2011 11:29 pm

Concur with les.


Neil MG
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Re: is dot4 synthetic compatible?

Postby Neil MG » Fri Mar 04, 2011 1:59 pm

Just for the record Silicon fluid WILL NOT mix with DOT 4. They are NOT compatible. Before switching from one to the other the system needs to be completely flushed and ideally all seals and hoses changed!

There is a lot of debate over which is best silicon or DOT 4 and I could not hope to ever find agreement there. I am in the silicon camp because it doesn't damage paint and doesn't need to be changed every two years. But I also respect that some people have had problems and would never use it.

There should be no debate about compatibility! Again I would say for an immediate evidence of this just mix a little of each in a container. Give it a good shake or stir and watch the two fluids emulsify and then settle.

My advice to anyone who has mixed fluids is to drain and flush the system, change the seals and hoses and refill with one or the other.
1956 Morris Minor Series II
1959 MGA 1600 Roadster
1966 Jaguar Mk2 3.8 MOD

Stig
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Re: is dot4 synthetic compatible?

Postby Stig » Fri Mar 04, 2011 3:33 pm

I didn't say they'd mix, they're different densities so they don't. That doesn't mean they're not compatible. After all, water does mix rather well with glycol fluid but that doesn't mean it's a good idea to put it in your braking system!

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Re: is dot4 synthetic compatible?

Postby Neil MG » Fri Mar 04, 2011 6:41 pm

OK we can agree to differ, but I would recommend that anyone who is thinking of mixing or thinks that the two fluids may be compatible to at least do a bit of research (start with google!) before proceeding.
1956 Morris Minor Series II
1959 MGA 1600 Roadster
1966 Jaguar Mk2 3.8 MOD

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Re: is dot4 synthetic compatible?

Postby charlie_morris_minor » Fri Mar 04, 2011 7:41 pm

my dad put silicon in his MO but that was when we replaced all cylinders and lines

xpress
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Re: is dot4 synthetic compatible?

Postby xpress » Fri Mar 04, 2011 9:10 pm

Charles are you going to brooklands? :)


charlie_morris_minor
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Re: is dot4 synthetic compatible?

Postby charlie_morris_minor » Sat Mar 05, 2011 6:01 am

No I am on call for work unfortunately


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