Brake Fluid

[Pete C]

Hi All,
What is the recommended brake and clutch fluid to use? I believe I am to stay away from silicone fluids. One recommendation was Motul 660 Dot 4 non-silicone synthetic. Thanks for the help.

[SENC]

https://smile.amazon.com/dp/B0093PHU9C/ref=dp_cerb_1

[Elan45]

+1 on the product.

Over the last few years, I've only found it available on the internet and I've been buying it through ebay

I use it in my Elans, and my vintage racing Eleven and 20/22 Formula Jr. Its heat resistance is good enough that it will be used in my Sebring Sprite and Modus F3 and probabable in my Corolla AE86 GTS next summer when I go through the brakes

Roger

[nmauduit]

Its heat resistance is good enough that it will be used in my Sebring Sprite and Modus F3 and probabable in my Corolla AE86 GTS next summer when I go through the brakes

fwiw its boiling temperature is the same as DOT5 (silicone) brake fluid : 260°C

[661]

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'.

[steve lyle]

Any DOT 4 will give you an elevated boiling point over DOT 3, but some are higher than others. See: https://www.lelandwest.com/brake-fluid- ... -chart.cfm

[nmauduit]

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.

[gherlt]

Hello Pete,
first you would need to define the use. in absolute normal street use, there is no need for anything higher than DOT4. If you have a "hotter" style, the you could decide to use DOT 5, which is kind of one-way.

But I personally go with the DOT 5.1 (Motul has one), which is a bettered version of DOT4, but not silicone. It does mix with DOT4/3, no problems, it does does not degrade as much with water.
All the way better, but compatible with the rest.

[alan.barker]

I have 2 cars where the brake fluid is dot 4 .
I also have a car where the brake fluid is Silicone.
No problems with either but i NEVER MIX or change just stay with the same in each car.
Alan

[mbell]

I bought a bottle of motul 660 as wanted some good fluid given single circuit brakes and high temps in this part of the world. After reading the bottle I decided against using it due to concerns about water absorbsion as the car isn't used much and don't want to change the fluid very frequently. So I went with regular brake fluid, which I should probably change out now.

[Pete C]

Thanks for all the input.
I use the car for pleasure driving, touring.
My concern arose when my clutch drained the fluid and the rubber was swollen. Old fluid- Castrol of some sort and I may have mixed fluid types, and the system was last rebuilt 20 plus years ago.

The Castrol should be suitable for my driving. Thank you all again.
Pete

67 Elan S3

[tdskip]

Why not DOT5 if everything is brand new?

[steve lyle]

Why not DOT5 if everything is brand new?

I asked this question of the Corvette board a while back. The answer I got was that DOT5 is more compressable than glycol-based fluids, so your pedal might feel more spongy to you. This might be why there aren't any OEM's that use DOT5 (that I'm aware of, anyway).

The Corvette guys that use DOT5 tend to be those that collect their cars, and don't drive them much. They prefer DOT5 because it doesn't strip paint, and it doesn't absorb water (so the boiling point remains high, which they don't really care about, and they don't get any internal rust, which they do care about).

Meanwhile, of the guys that track their cars, basically none use DOT, they say for the compressability reasons.