I know there is a lot of info out there, but I cannot find the answer. Please help. I currently use SRF and I love it. Previously I needed its high boiling point due to weight of my car, lack of ducts and poor braking technique. I have remedied those weaknesses and therefore I believe I can safely afford to slightly lower the boiling point of the fluid used. My question originates from a persistent rumor, which came to me via multiple trusted “expert” sources. Some people claim that SRF eats through rubber. Also some teams seems to have problems calibrating there brake system after the car been parked in a garage during the off season. Now, in my car, I have not found evidence for either of these. My car was idle for 9 month and after some bleeding brakes seems to work flawlessly. I also do not see any leaks and the brakes display normal level of firmness. However, I have no measurements to support my observations. Nor is my system precise enough to really feel minor effects.

Question: 1) can anybody confirm the rumor or show evidence in its opposition? 2) does anybody know if GS610 is corrosive or might create some negative side effects for the brake system? 3) does anybody have any info comparing compressibility of SRF vs. GS610?

I am replacing calipers and an ABS module. I might upgrade master cylinder while I am at it. So a complete system flush is in my near future. Thus, if I must, now would be a great time to switch fluids.

Thanks.

:werd:

Ive never heard of it causing any negative side effects.

GS610: 8.91 lbs/gal
SRF: 1.065 lbs/gal

GS610 is cheaper though.

Thanks for reply. I too saw the density chart http://www.bobbyarchermotorsports.com/pdf_2848_3.pdf (http://www.bobbyarchermotorsports.com/pdf_2848_3.pdf) but I am not sure if density is the correct measure for compressibility for synthetically created brake fluid. According to these numbers GS610 would be 8 times less comprisable than SFR. If true, that would make GS610 the fluid to buy. Yes, its wet boiling point is significantly lower than that of SFR, but at half the price one can bleed twice as much. However, I am very skeptical that SFR is 8 times more comprisable than GS610. I imagine a cubic foot of steel is heavier than that of carbon fiber, but I doubt cf is more comprisable.


BTW, according to Castrol literature SFR is safe on rubber seal, but because it is publish by their marketing guys I take it with a lb of salt. :) http://www.castrol.com/liveassets/bp_internet/castrol/castrol_australia/STAGING/local_assets/downloads/s/SRF_B768.pdf (http://www.castrol.com/liveassets/bp_internet/castrol/castrol_australia/STAGING/local_assets/downloads/s/SRF_B768.pdf)

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My old T2 M3 has been using it continuously since 1997 without one problem. Continue to use it. And quit telling everyone your using it :) (its one of my secret weapons (all the guys running Motul complain about getting fade on hot days and I dont have any problems...))

Density of a fluid has very little correlation with its compressibility. In fact, almost all liquids will have extremely little compressibility with a few exceptions.

Density of a fluid has very little correlation with its compressibility. In fact, almost all liquids will have extremely little compressibility with a few exceptions.

Bullshit, explain.....

Sure a liquid is not compressible, insert moisture and expand to a gas at temp, and it's a different story.

BTW - SRF is ridiculous in its durability w/r to consistent performance.

Bullshit, explain.....

Sure a liquid is not compressible, insert moisture and expand to a gas at temp, and it's a different story.

BTW - SRF is ridiculous in its durability w/r to consistent performance.

I have never used either, so I would like to think I am unbiased.

OK, so pure liquid is essentially not compressable. Then insert moisture, assuming you mean water = liquid = basically imcompressable in liquid form. Expand to gas, and we know gas = very compressable. If there is any air dissolved air in the fluid (understand this to be common to varying degrees), THAT is compressable, which will make it seem that the brake fluid is compressable.

I believe GS610 markets that their fluid has less air in solution, but again, never used it.

Which fluid has a lower viscosity?

I guess I am missing something here. All brake fluids, in their purest form, are going to have virtually indistinguishable compressibility to the driver. It is their behavior when you add the unavoidable moisture and air into the system that we worry about. I only pay attention to the wet point because I am too lazy to flush my fluid every track weekend. SRF is not corrosive.

Bullshit, explain.....

Sure a liquid is not compressible, insert moisture and expand to a gas at temp, and it's a different story.

BTW - SRF is ridiculous in its durability w/r to consistent performance.

Well... then you're talking about compressing a gas then aren't you? The ideal gas law does a good enough job of approximating what happens after that.

My statement is still true, even if you didn't read it correctly.