Motul RBF600 or 5.1?

[Asmodeus]

Hey guys,

I noticed that my current brake fluid (BMW DOT4) is pitch black after only one year of use. I was discussing with some friends about sticking to OEM or looking at other options and was recommended Motul.

However it's a 50/50 split between RBF600 and 5.1

Do I track my car? No, but I drive it hard enough that some might consider it track.

Also, being in Canada, I need to be sure that the oil is capable of properly functioning at -40C.

Oh, about the car, it's a 328i E46. In case that helps.

Thanks for helping me out with this

 

[Titanium_Alloy]

Motul 5.1, if I'm not mistaken, has much better cold temperature performance compared to many other fluids including all DOT 4. For DOT 5.1 rated brake fluid viscosity must be less than 900 cSt at -40 C. For DOT 4 it must be less than 1800 cSt and DOT 3 must have viscosity of less than 1500 cSt. I believe cold temperature performance of DOT 3 brake fluid is one of the reasons American car makers recommend it instead of DOT 4. Motul 600 has viscosity of 1525 cSt at -40C. Since you live in Canada (and probably have ABS on your car) I'd definitely go with Motul 5.1. Motul 600 seems like one of the best fluids for hot summer track event, although I wouldn’t even think twice about using Motul 5.1 in the same track conditions. It looks to me like Motul 5.1 offers the best combination of low and high temperature performance. I would go with Motul 5.1 in any car without a doubt. I must mention that I haven't used either of these brake fluids because they are really expensive.

Regards,

 

[Labatt Bear]

I've been using Motul 5.1 on my 01 Trans Am. It is much cheaper than Motul RBF 600. Since I don't do auto-x, its dry and wet boiling points are good enough for me.

MOTUL 5.1
Dry Boiling 518F
Wet Boiling 365F

MOTUL RBF 600
Dry Boiling 593F
Wet Boiling 420F

Here are the links for product specification:
http://www.turbofrogperformance.com/PDF_files/DOT_51.1_Brake_Fluid.pdf
http://www.turbofrogperformance.com/PDF_files/RBF_600_Factory_Line.pdf

 

[Asmodeus]

Titanium:

Thank you for your feedback. I personally was leaning towards 5.1, but am not knowledgeable enough with respects to brake fluids to pick one over the other (with total confidence).

And I agree, Motul products are very expensive. 5.1 is roughly $14/L (CDN), and their 5W40 (which I am using) is now close to $20/L.

Once again, thanks