661 wrote:I've used Motul 600 in all the cars for some time after having some brake boiling with the OEM ( Lotus Exige) stuff.
I've had no issues with it but have recently move to 660 for 'security'.
for racing (e.g. on a friend's Etype, faster and heavier than an Elan...) I've used Motul RBF660 : quite a significant increase in boil temp (325°C), but also very corrosive and prone to absorb water, so frequent purge are the essence (every race in our schedule)... that's ok for a race car, but my street elan is only a "fast road", plus the convenience of non corrosive hydraulic fluid ends up very pleasant as eventually it always ends up on the paint somewhere.
Granted, silicone DOT5 does boil at 260°C, but I might have improved a bit over the years as the dreaded pedal to the floor at the end of the straight has not happened to me for several years now (in spite of Pagid RSH3 at the front on 16P calipers, which do brake hard if you insist, yet fade appears before the fluid boils when I let myself endulge with overbraking). Also, there are a few tricks one can use to shield the fluid (castelated pistons, stainless or titanium shield between piston and pad ...).
I use silicone DOT5 on other vintage vehicles ('75 BMW R90S, Cadillac from the 50es ...) used somewhat infrequently, and for these the convenience of being able to trust the brake system not to be clogged due to internal corrosion largely outweights the cost of DOT5 to me.