brake fluid

BillGrissom said

I don't notice a spongy pedal in any of my cars. There is slight "lost motion", but that is normal (pads & shoes must move to contact). Racers use glycol because it has a slightly higher boiling point when new and pristine. They probably flush it before every race, plus rebuild the engine and tranny, etc. The main reason silicone is hard to find is because it is not recommended for ABS systems, which are everywhere today. I don't know if there are known problems or it was just never tested and qualified (i.e. accountants & lawyers input).

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Yes exactly. It road, circle track and that type of racing where some of silicone's slight compressibility becomes more of an issue. IIRC it has to due with the heat transfer and brake pressures involved. Agree that brakes should be bled before each race or weekend, and at minimum begining of every season.

Of course if the car is VERY Heavy and VERY Fast and uses front disks, then fluid temperature and condition could effect stopping at the end of the drag strip too. Drum brakes better isolate the fluid from the heat of friction so less likely to have issue with degraded fluid temperature.

That said, I've found it best to bleed the brakes of my vehicles every spring even for street use. Doing so really reduces the amount of fine rust which is hell on caliper pistons. For years I was using Castrol's LMA but after discovering Valvoline's "Synthetic" (now renamed something else) I've been sold on it because the fluid comes out much cleaner during the annual bleed.