StriderTacticaL

Ok so I bought my car with 27k miles on it and right now it is just under 30k. I kinda feel that my braking effort is increasing but my pads are still good. I spoke to my dad about this and he told me that brake fluid change isn't usual maintance and since my car had like 27k on it, it likely has not yet been changed.


He told me to just get a syringe and suck up as much as I can from the fluid reservoir and just put in the new fluid. Having some of the old ones in the line won't be a problem he said.

My question is which kind of fluid/brand am I suppose to get? So it's ok to mix it with a bit of the old fluid still left in the lines? Can I just suck up and refill the reservior, is it that simple?


Thanks,
Brandon

.boB

For street use, pretty much any DoT3 fluid will be fine. I tend to use Castrol, but it probably doesn't really matter.

You can use a syringe to remove the old fluid from the MC. But you have to move kinda quick. Brake fluid eats the plunger. I use a turkey baster.

BUT, you also need to fluch out the fluid that's in the calipers and line. This is the fluid that does most of the work, and gets all the abuse. The MC never heats up, but the calipers do. You need to bleed/flush all the lines until you get clean fluid.

RuffCat

Theres more fluid in the lines and calipers and ABS unit than you realize. It's where most of the fluid is. The calipers are what retain and create the dirty fluid. Brake fluis is one of the most common disregarded maintenence item on vehicle. Most people would drive 100kmi and not even think of changing the brake fluid. Others wouldn't even think that it ever needs to be changed. Actually, brake fluis is reccomended every 30-60kmi depending on the conditions.
I switched to Valvoline synthetic. My best answer for you is to get some Valvoline Synthetic the tall bottle. DO NOT EMPTY YOUR RESEVOIR as you will get air in the lines!!! You can take some fluid out, but don't go past the nipples on the side. Pour the new fluid in and start to bleed your lines one-by one so it pushes the old fluid out and the new fluid in. Do this on all the lines until you get a clean fluid coming through. Keep an eye on the resecoir and keep it filled. The fluid will be cleaner looking even if it already looks pretty good. It should be almost clear and not yellowed. You need to have someone pumping the brakes to do this or get a one man bleeder (I hate those things...PIA)
This process will put new fluid in your lines and calipers and allow you to keep your calipers hooked up and not get excessive air in the lines.

StriderTacticaL

Thanks for the replies. So I guess it's a bit more involved than I thought. I was hoping to just take most of it out from the reservoir and then add in the new fluid, drive around and have it mix up and then change it again until *most* of the old fluid is out. I guess this is not really a good idea huh?

.boB

No, not a good idea. I would take a long time for the fluid to find it's way from the MC to the calipers; if it ever does. Fluid does not really flow through the system. When you mash the pedal, it moves foreward. When you let up it flows back. But it's a small amount of fluid.

Face it. You just have to bleed each caliper until you get clean fluid.

Synthetic fluid is not a good idea in a street car. It has a very high boiling point, and that's good in racing. In street cars it rarely gets high enough to matter. Synthetic fluid is hydrophobic; meaning it repels water. That's a bad thing. Water will pool instead of mixing. Water is heavier, so it always ends up on the caliper. The boiling point of water is a heck of a lot less than brake fluid. It will also cause the inside of the caliper to rust.

Harley's used to come from the factory with DoT5 synthetic. You had to bleed every year or two.

You cannot mix glycol and synthetic DoT5 brake fluids. It will clot. If you want to switch to a non-glycol fluid, you have to completly disassemble and clean the entire braking system, put in new seals, and then fill with synthetic.

There are really only 2 common fluids you can use, DoT3 and DoT4. There's a DoT5.1 that is glycol based and has specs similar to synthetic DoT5; but it's really hard to find. Companies like Wilwood, Baer, Motul, etc, also market some high performance fluids. They're expensive, and a real waste of money in a street car.

StriderTacticaL

.boB thank you for your post. So when you said that synthetic fluid will not mix in with water, regular fluid will do just that right?

What is glycol? or is glycol just regular fluid and DOT 5 is synthetic? So DOT 3 and 4 is non-synthetic right? wahts the difference between them?

_Slowbra_

just go into autozone, get a bottle of DOT3 fluid, brands dont matter. Then empty MOST of fluid out of the MC and refill with new fluid (DO NOT empty the reservoir because you will get air in the lines=no brakes). Then go around to each caliper and bleed each line until you only see clean fluid coming out. DO NOT bleed the brakes on a painted driveway/garage, the brake fluid will eat away at almost anything it spills on. After you bleed each line/caliper refill the MC with the rest of the new fluid and you are good to go.

Just go with any DOT3 fluid, any of them are fine. Dont worry about synthetic stuff, youre not running the 24 hrs of Le Mans so you dont need it (as stated above).

.boB

The glycol fluids are DoT3, DoT4 and DoT5.1. They can all be mixed together without any problems. The high performance fluids from companies like Wilwood are usually glycol base - but you have to read the labels to be sure.

The glycol based fluids are hydrophyllic. Water will mix with them, and disperse throught the system without pooling. That's a good thing, but also the reason for changing the fluid.

Synthetics are DoT5. They are not glycol based, and don't mix with the glycol fluids. They are hydrophobic. Water doesn't mix with them, and that's a good thing in a race car. A bad thing in a street car.

I use glycol Wilwood 570 in my track/street car, and DoT4 in everything else.