Brake Fluid Advice

**Halon** · 03-29-2009

My car is a 1991. I have a very strong feeling that the brake fluid in this car is still the factory stuff. I also notice when pressing hard on the brakes, that the car pulls. Something I want to do is just completely flush out the brake system and get some new fluid in there.

I'm no brake fluid expert, so I'd like to hear what a good fluid to use would be. I've done some searching and it sounds like ATE makes some good fluid. But I'm not convinced it is for me.

This car is a summer toy, that I just toy around on the streets most of the time. See's very little track time. So, I'm not looking for the best Race Ready fluid on the planet. Whatever fluid I use, I would prefer to not have to replace it again at all soon, or in the next 5 years for that matter. I've heard that some of the better fluids may perform better, but don't last as long because of moisture. I'm trying to simply find a fluid that is a good compromise between performance, and longevity.

Open to any suggestions, but please keep my goal in mind. I don't AutoX the car or anything like that. Just some hard braking after a pull here and there, that's it. Would something like sythetic Valvoline stuff work?

MustGoFaster · 03-29-2009

That synthetic valvoline stuff is what I run. Easy to find, and a good fluid to boot. Never had an issue with it, even at track days. But really, if your not going to put a ton of stress on the brake system, even the parts store generic stuff would work just fine.

As for the pulling, your going to want to check your brake pads, caliper slides, and pistons. If a slide or piston has stuck it will wear out the pads on one side, and then the braking forces are unbalanced so the car pulls. If the fluid has never been bled, it's going to be dark in color. New fluid is clear, with maybe a slight hint of yellow.

If the fluid has never been bled, if end up with water in it. It just absorbs it through the rubber and what not. And then it collects down in the caliper and rusts inside and makes the piston(s) stick.

**Kracka** · 03-29-2009

Valvoline Synpower DOT4 is some of the best off-the-shelf fluid you can find at most stores and is more fluid than 99.9% of drivers will ever need. If you want to go a bit better b/c you plan on tracking the car there is ATE Super Blue (which is what I purchased), or even better yet, AMSOIL DOT4. MOTUL is also a popular choice, but it doesn't belong in street cars since its good for 6 months max. The better the brake fluid, the more expensive it is and the more frequently it needs bleeding/flushing. The Valvoline Syn is a good choice for you since its a high-performance fluid that will last for a few years w/o a problem.

sleepydsm · 03-29-2009

Wouldn't just plain off the shelf DOT4 be good enough? Pulling to one side while braking, assuming your front end bushings are solid, would indicate a problem like a seized caliper slide or stuck pads.

deadeye · 03-30-2009

As long as your running DOT4 your fine. It has to meet a minumum standard to get that rating so any fluid rated that way will work. The valvoline stuff has always been good and its pretty cheap so go for it.

MGF hit it right on with this one. As far as the pull goes, it may or may not have to do with the brake fluid. Given that you are thinking its stock stuff after 18 years it might a cause to a bigger problem. The fluid absorbs water causing the pistons/cylinders in the caliper to rust. This creates a slow/stuck piston which gives you less braking pressure on one side causing a pull. However you could have a stuck/sticky slide from lack of lube too. Tough to say without pulling it apart.

I would suck out the brake fluid in the M/C and replace it with clean stuff and then bleed the brakes until it flows clear. Start at the pass rear and work your way up. Then clean up the caliper slides and lube them up real nice and see what happens. If your lucky it will clear up the pull for less than 10 bucks. Otherwise a set of rebuilt calipers may be needed.

lucasoil4u · 04-01-2009

i work at a parts store nd valovine dot4 is really good stuff that lasts a long time...i recomend it!

Speedfreak · 04-01-2009

Quote:

Originally Posted by MustGoFaster

That synthetic valvoline stuff is what I run. Easy to find, and a good fluid to boot. Never had an issue with it, even at track days. But really, if your not going to put a ton of stress on the brake system, even the parts store generic stuff would work just fine.

As for the pulling, your going to want to check your brake pads, caliper slides, and pistons. If a slide or piston has stuck it will wear out the pads on one side, and then the braking forces are unbalanced so the car pulls. If the fluid has never been bled, it's going to be dark in color. New fluid is clear, with maybe a slight hint of yellow.

If the fluid has never been bled, if end up with water in it. It just absorbs it through the rubber and what not. And then it collects down in the caliper and rusts inside and makes the piston(s) stick.

Correct

Quote:

Originally Posted by Kracka

Valvoline Synpower DOT4 is some of the best off-the-shelf fluid you can find at most stores and is more fluid than 99.9% of drivers will ever need. If you want to go a bit better b/c you plan on tracking the car there is ATE Super Blue (which is what I purchased), or even better yet, AMSOIL DOT4. MOTUL is also a popular choice, but it doesn't belong in street cars since its good for 6 months max. The better the brake fluid, the more expensive it is and the more frequently it needs bleeding/flushing. The Valvoline Syn is a good choice for you since its a high-performance fluid that will last for a few years w/o a problem.

Pretty much spot on.

niterydr · 04-01-2009

Kracka, not to go off topic, but do you have a link for the Motul fluid expiring after 6 months? I never had a problem with it in my stealth and used it for a few years...
The valvoline dot 4 stuff is awesome for stuff you can get practically anywhere. That is what the Audi will get when a brake upgrade happens (2011, lol).

**Kracka** · 04-01-2009

Swanny, it won't just "expire" after 6 months, but it absorbs so much water it drops the boiling point down below a safe level. Like any brake fluid (which generally lasts only 2-3 years at the most) you'll never notice when it goes bad on the street because the fact of the matter is most of us don't drive that hard on the streets and don't push the brakes that hard. But, if you needed to, with the old fluid, the brakes might not be there for you when you most need them. This is why most tracks (I'm not talking drag racing) require brake fluid to be fresh, and at the most, only 6 months old and not discolored at all to be considered safe.

Here is a quick link for you with some basic brake info. Its on EvoM, but it pretty much repeats all the same stuff discussed on auto-x, S2k, etc. forums:
http://forums.evolutionm.net/evo-tir...ct-thread.html

niterydr · 04-01-2009

Quote:

Originally Posted by Kracka

Swanny, it won't just "expire" after 6 months, but it absorbs so much water it drops the boiling point down below a safe level. Like any brake fluid (which generally lasts only 2-3 years at the most) you'll never notice when it goes bad on the street because the fact of the matter is most of us don't drive that hard on the streets and don't push the brakes that hard. But, if you needed to, with the old fluid, the brakes might not be there for you when you most need them. This is why most tracks (I'm not talking drag racing) require brake fluid to be fresh, and at the most, only 6 months old and not discolored at all to be considered safe.

Here is a quick link for you with some basic brake info. Its on EvoM, but it pretty much repeats all the same stuff discussed on auto-x, S2k, etc. forums:
http://forums.evolutionm.net/evo-tir...ct-thread.html

Sweet, well I will check this when I get home.

Speedfreak · 04-01-2009

While I haven't heard too much about the high rate of moisture absorption of Motul, I've read about having to change it more often. However I'd bet that is due to the "normal" use that people who actually use Motul are subjecting the fluid to(track days etc). Here is a thread about it on H-T(the dealership/source is well respected in the NSX community):

http://www.honda-tech.com/showthread.php?t=1612881

I'd say sticking with the Motul over long periods of time is just fine for 99% of the people out there. But if you are road coursing it time after time, I'd change it more often.. Like you would with ANY fluid. So no loss if you ask me.

**Kracka** · 04-01-2009

Please also keep in mind the high performance fluids that absorb water more quickly will also hold that moisture down in the brake calipers causing the internals to rust much more quickly.

**Kracka** · 04-01-2009

Quote:

Originally Posted by Speedfreak

While I haven't heard too much about the high rate of moisture absorption of Motul, I've read about having to change it more often.

It requires more frequent change than traditional brake fluid due to being more hygroscopic.

**Halon** · 04-01-2009

OK, so I will either run off the shelf crap, or Valvoline Syn if it's not that much more expensive.

Thanks everyone.

turbotalon1g · 04-01-2009

i have a bottle of valvoline syn you could use, i know you won't use all of it.

**Kracka** · 04-01-2009

Once a bottle of brake fluid is open whatever you don't use right away is as good as junk and should just be tossed (if you care about keeping your braking system 100%) since it sits there on the shelf absorbing moisture from the air now inside the container. Yes this it nitpicky; please see my user title

MustGoFaster · 04-01-2009

Quote:

Originally Posted by Kracka

Once a bottle of brake fluid is open whatever you don't use right away is as good as junk and should just be tossed (if you care about keeping your braking system 100%) since it sits there on the shelf absorbing moisture from the air now inside the container. Yes this it nitpicky; please see my user title

+1

In the event I don't use the whole bottle right away (~ 1 month) I consider it just regular brake fluid and pour it in any car that needs some.

Ihearrtdsm · 04-01-2009

thanks for the info, didn't know some of that.

niterydr · 04-02-2009

Quote:

Originally Posted by MustGoFaster

+1

In the event I don't use the whole bottle right away (~ 1 month) I consider it just regular brake fluid and pour it in any car that needs some.

What ryan meant to say was any of the lesser domestic vehicles in his driveway

iceminion · 04-02-2009

When I replace master/slave/flex line for the clutch setup, I always clean the hard lines out, and then use DOT5 synthetic, good enough for motorcycles, good enough for me....anyone use DOT5 here?