Brake fluid in power steering?

My 2002 Renault Scenic has on the power steering cap "use DOT 4 brake fluid" so I did, then realised it was not the brake reservoir! Should I be concerned? It was just a small topup. Does it have the wrong cap?
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On 19/05/2019 13:32, Commander Kinsey wrote:

Have a look in manual that came with the car.
Bill
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On Sunday, May 19, 2019 at 9:07:23 AM UTC-4, Bill Wright wrote:

+1
First time I've heard of using brake fluid in the power steering, but they are both hydraulic systems. And this is a French car, wouldn't be surprised if they used wine. Seems it's probably right, unless the caps are the same for brake and steering and someone mixed them up.
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Google claims one is petroleum based, one isn't, and I might damage rubber seals. Ah well, if it's already losing fluid....

ROTFPMSL!

The brake cap also says use brake fluid, but it says "use DOT 3 or 4", it's a different cap altogether, different shape with a sensor on it.
I'll assume a small amount won't do too much harm, and in future just use the correct fluid in each, although I don't think you can still get DOT 3 or 4, I just use 5. 5 is better, right?
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On 05/19/2019 07:49 AM, Commander Kinsey wrote:

The devil is in the details... DOT 5 is a silicone based fluid that is incompatible with 3, 4, and 5.1. Mixing the two results in sludge. Changing from one to the other requires a complete system flush.
I have 5 in one motorcycle since that's what Harley used in the '90s. It's viscosity is supposedly more stable and it doesn't damage paint. It doesn't work in ABS systems. I'm too lazy to change it but it's hard to find since it never gained popularity. It's purple so it is easily distinguished.
DOT 5.1 is compatible with 3 and 4.
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I meant 5.1. I've never heard of anything asking for 5, I guess it was a short lived idea.
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On 05/19/2019 12:43 PM, Commander Kinsey wrote:

It's popular with the custom and classic car crowd. The other flavors are decent paint removers. Also, it doesn't absorb water which can be helpful if the vehicle isn't driven frequently.
The downside is it does entrain air and can be a bitch to bleed and get a firm pedal. Also, silicone contamination is a painter's nightmare. It doesn't take much contamination to cause fisheyes.
So mostly it was a brainstorm that didn't pan out. One of the selling points is its high boiling point that was supposed to be ideal for racing applications. The fly in that ointment was if any water got into the system it would not mix like it will with DOT 4, and the water would boil at 212. I believe it is completely banned from racing now.
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I wonder why the numbering is so wrong? It should have a different number if it's completely different. You'd expect 5 and 5.1 to be the most similar.
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On 05/19/2019 01:38 PM, Commander Kinsey wrote:

You do have to wonder about that... USB fell into the same shitpile. There used to be USB 3.0 that became USB 3.1 Gen 1 that now is USB 3.2 Gen 1. USB 3.1 became USB 3.2 Gen 2, and 3.2 became USB 3.2 Gen 2x2.
At least Microsoft saw the trap. .NET CORE is sort of a cross platform .NET and started at 1.0. It's now up to the 3.0 RC. Meanwhile .NET Framework started at 1.0 and is up to 4.8.
The next generation will blend CORE and Framework into 5.0 so there will never be a .NET CORE 4.x.
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wrote:

The brake fluid numbering makes sense when you realise what they are doing. Each higher number fr DPOT5.1 has a higher boiling point - the most important "mumber" for brake fluid. 5.0 was almost a total bomb -so 5.1 was brought out as it's replacement - with virtually the same BP spec.
Trying to make sense of any numbering system other than binary code in computers is futile.
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On 05/19/2019 04:38 PM, Clare Snyder wrote:

It would have made more sense to call it 6. If 5 wasn't rare on the part store shelves, how many people would have screwed up their brake system by buying it instead of 5.1? Even going by boiling point 5 is 260 C and 5.1 is 270 C.
For that matter DOT 2 (castor oil) has a higher boiling point than any of them.
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wrote:

Cite?
DOT 2 Brake Fluid. DOT 2 brake fluid is oil-based, and it isn't widely used in the automotive industry. It has the lowest wet and dry boiling points of all the brake fluids. If your vehicle calls for Dot 3, 4, or 5 fluid, you shouldn't add DOT 2 fluid.Oct 23, 2013
DOT2 was a mix of Castor oil and alcohol - with a boiling point of only 140c wet and 190 dry.( https://en.wikipedia.org/wiki/Brake_fluid )
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So apart from DOT 5.0, I can always use a higher DOT number? I assume the car doesn't care if the fluid is capable of a higher temperature. Are there no drawbacks to the higher numbers? Corrosiveness etc?
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On 05/20/2019 11:33 AM, Commander Kinsey wrote:

Cost? 4 is usually a little cheaper than 5.1 but it's not like either is really expensive. It's the 5 that is pricey and sometimes hard to find.
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All I can ever find is 5.1. And it only costs a few quid.
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From 17 years ago and 5 previous owners?! Yeah like I know where that is.
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On Sun, 19 May 2019 14:49:54 +0100

You could join these folks, and ask:
https://www.renaultforums.co.uk/
--
Davey.

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On 19/05/2019 15:10, Davey wrote:

Not much point as he is making the stuff up. He makes most of it up.
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On 5/19/2019 10:58 AM, dennis@home wrote:

You are right when you see the source. Old formally known as JW Sword changes his name frequently.
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Trivially downloadable.
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