D3 TDV6 Brake fluid options

[LR3 Disco Owner]

Ok, so I've been doing some research into brake fluid options as I recently replaced all discs, pads, shoes and sensors. Hopefully next time I have to do that I'll have a flat concrete floor to work on!
Anyway, after compressing all the pistons in the process of replacing the pads I had to drain off the excess fluid and it is looking fairly dark. In a syringe it has a greeny yellow tinge to it, but once the appropriate amount had been squirted into another container for disposal it was looking rather dark and opaque, so now I've added changing the brake fluid to my list of things to do.
I read previous threads on here about the use of different fluids, mainly Penrite and the OEM Shell fluid. There was talk of the Penrite Super Dot 4 and their Dot 4 ESP as alternatives to the Shell Dot 4 ESL.
The sticking point seems to be the ISO 4925 Class 6 specification, as many of the others I looked at including Castrol, Bosch, Valvoline, Nulon, the own brand ones and even the Penrite Super Dot 4 don't have that specification, rather they seem to be Class 3 or 4.
On looking at the Penrite website, they now actually specify their Dot 5.1 fluid for the Disco 3 TDV6, so I had a look at the specifications for the different fluids to properly compare them and they are shown below:

	Penrite Super Dot 4	Penrite Dot 5.1	Penrite Dot 4 ESP	Shell Dot 4 ESL
Density at 20°C, kg/L	1.069	1.067	1.055	1.058
Viscosity, Kinematic, cSt at -40°C	1147	690	700	716
Viscosity, Kinematic, cSt at 100°C	2.23	2.04	2.1	2.1
Equilibrium Reflux Boiling Point (wet)	183	184	165	181
Equilibrium Reflux Boiling Point (dry)	275	274	260	273

As you can see the specs confirm that the Super Dot 4 seems to be a slightly different beast and although they have the information for it, I found mention that the Dot 4 ESP has actually been discontinued.
So moving forward do people feel that the Dot 5.1 is a readily available alternative, and at $30 for 500ml how does it compare to the dealership prices, as I'm waiting to hear back from my nearest dealer? Is anyone already using it and what are peoples thoughts on using DOT 5.1 rather than 4, are there any downsides apart from the price?

[DiscoJeffster]

For this reason I just buy a litre from the dealer every few years and suck up the cost. I don’t recall it being that much.

In fact, I added it to one of my online orders from the UK - 1 litre, GBP 11.05.

[PerthDisco]

The Nulon Dot 4 in yellow bottle in SCA has the ISO 4925 rating that’s important. Only needs to be Dot 4 with that rating and no more complex.

[DiscoJeffster]

The Nulon Dot 4 in yellow bottle in SCA has the ISO 4925 rating that’s important. Only needs to be Dot 4 with that rating and no more complex.

Sorry that’s incorrect. It needs to be 4925 class 6 which is very different. 4925 is broken into many specs. It saying 4925 and not specifying the class is useless. I note the specs for viscosity on their documentation for that fluid do not make it class 6 viscosity compatible.

Penrite have their DOT4ESP which is up to class 6 compatible.

[LR3 Disco Owner]

And there's the kicker, ISO 4925 Class 6 states that the viscosity has to be at or below 750 whereas Class 4 is at or below 1800.
Now the ISO standard also says that Super DOT 4 should be Class 6, but both the Nulon and the Penrite don't meet the Class 6 specification with viscosities of 1231 and 1147 respectively, instead they just list that they meet ISO 4925 and don't mention the Class, could this be to deliberately mislead, as people would rightly assume that since it is Super DOT 4 that it should be Class 6?
I'd be interested to see a graph of the viscosity against temp to see how they compare at around 0 degrees as that's probably more applicable here than -40!

[DiscoJeffster]

And there's the kicker, ISO 4925 Class 6 states that the viscosity has to be at or below 750 whereas Class 4 is at or below 1800.
Now the ISO standard also says that Super DOT 4 should be Class 6, but both the Nulon and the Penrite don't meet the Class 6 specification with viscosities of 1231 and 1147 respectively, instead they just list that they meet ISO 4925 and don't mention the Class, could this be to deliberately mislead, as people would rightly assume that since it is Super DOT 4 that it should be Class 6?
I'd be interested to see a graph of the viscosity against temp to see how they compare at around 0 degrees as that's probably more applicable here than -40!

Exactly. I did the same research. They’re deliberately misleading in my opinion hence I just went with genuine, but there are alternatives such as the Penrite, if you can find it

[LR3 Disco Owner]

Penrite have their DOT4ESP which is up to class 6 compatible.

Unfortunately their website says they are discontinuing it and that the 5.1 is the replacement.

[BradC]

Penrite have their DOT4ESP which is up to class 6 compatible.

I used this for my last flush. Car hasn’t burst into flames and the abs still works. I still need to flush the clutch slave, but I keep putting that off.

The fluid that came out of the front calipers looked like mud.

[101RRS]

I just buy mine from a dealer - is the same cost as some after market fluid from Supercheap.

[PerthDisco]

Sorry that’s incorrect. It needs to be 4925 class 6 which is very different. 4925 is broken into many specs. It saying 4925 and not specifying the class is useless. I note the specs for viscosity on their documentation for that fluid do not make it class 6 viscosity compatible.

Penrite have their DOT4ESP which is up to class 6 compatible.

And I thought for the first time I found the correct part without several days of research! I scanned Bodsy’s Bible who does mention Class 6 but I just saw the bit where he says 4925 is important.