is this brake fluid compatible with the 993 system or not? I read that it based on silicone ester technology. However, I have heard that a silicone based brake fluid should not be used in the 993 system.
True or False ?

I have heard read that some people are using it. Any issues with swelling rubber? Leaks?

 

All DoT 4 brake fluid is compatible by law, That includes SRF
silicon based fluid is DoT 5 and is not recommended for normal use
While SRF is one of the best fluids available(It's wet boiling point is over 100F higher than the next best fluid) it is also expensive and not usually necessary unless the brakes are thermally overstressed. 993 brakes are generally not particularly stressed. All the other DoT 4s cluster around the low 400 to high 300F range. Including ATE 200

oe fill is ATE 200 which is also a DoT 4 fluid
.

 

So would it be ok to use it being that it is DOT4?

 

The compressibility of Castrol React SRF Racing is very similar to that of current DOT 3 and DOT 4 fluids.
It can therefore be filled into any braking system used in motor sport with the exception of those for which a mineral oil is prescribed.
It gives a “hard pedal” feel.
https://www.castrol.com/en_au/austra...rf-racing.html

no issues, but I feel silly when I spend that much on brake fluid.
motul rbf is half the price.
https://www.pegasusautoracing.com/gr...pID=BRAKEFLUID

 

yes

 

compressibility has nothing to do w/ compatibility, while compressibility does vary the range isn't very wide. DoT 3 is an older standard and generally not something you want to use in any 911 , 964, 993 et al. Dot 4 while compatible may not be best for older cars because of the effect of the borates used in 4 to raise the boiling point, similarly Dot3 isn't the beast choice for newer cars designed around 4.

The highest wet boiling points which is the main thing to look for after DoT 4 are all DoT 4 or 5.1(note Dot 5.1 is still a polyglycol-ether based fluid unlike DoT 5 which is silicon based and dyed purple)

For my street cars I use ATE200(or ATE bue which is 200 dyed blue)(388) for the track car Motul(though 200 worked fine there too until the pads get a bit thin)(400)

after SRF(518) the best is Torque RT700(439) then Project Mu(430) and Endless(424)

 

that is just a cut and paste from the linked website answering the op's question.
feel free to correct castrol's website

 

????

 

FWIW, I did notice a positive difference in feel (firmness) between endless and the brembo race fluid. I prefer the brembo fluid and gave a case of endless away when I changed. I have never had either fluid boil over or lose brake feel. I use ATE200 on street cars. Unfortunately brembo doesn't publish the wet spec, the dry is one of highest. I've asked my shop to call their contact to see if it's available.

 

There are several different varieties of Brembo brake fluid, the best is Brembo LCF600+, wet/dry is 399/601 it's also a DoT 4

 

OP are you using the car on track? If yes, RBF. If no, Pentosin DOT4 LV.