Synthetic brake fluid?

[fishguy1123]

I am planning on useing a turkey baster to drain and then replace with new fluid. Bought some prestone synthetic brake fluid (dot 3) yesterday and it dawned on me that I not all the fluid I've seen said synthetic on the lable. Is it ok to use this even if the old fluid isn't? Or are all brake fluids synthetic and they just put it on the lable to make it seem better? Thanks

 

[Badbart]

The best way to replace the brake fluid is to bleed the brakes at all four wheels. The turkey baster will only remove what you can see in the master cylinder. You'll still have all the old fluid and trash in the lines. And, no, not all brake fluid is synthetic.

 

[fishguy1123]

I know the bleed is the best. Was just gonna do the res for now since I'll be do in pads and rotors in the spring and bleed then. Figured it couldn't hurt. So is it ok to mix the fluid or will it cause problems since it's not a full swap?

 

[HARDTRAILZ]

I use DOT 4 and thought we were supposed to use it and not DOT 3, but I may have imagined that.

 

[fishguy1123]

I checked the cap on the res before I went inside to buy it. Says dot 3 on it.

 

[Hatchet]

i have a dot 3/dot 4 synthetic in mine...

the mixing i dont know. but if ur gunna do a bleed you mite as well wait till then. why waste the good new stuff by mixing it with the old crap over winter.

 

[fishguy1123]

I was going to do the same thing to the ps fluid and just dicided to do the bf at the same time I guess. Mostly was gonna tinker around a lil bit and it sounded like a good idea to me.

 

[Mark20]

As long as its DOT3 or DOT4 you can mix them. From what I've read DO NOT MIX DOT5 with either though.

 

[RayVoy]

It is my understanding, that DOT 3 and 4 fluid is glycol based and will absorb water.
The only diff between them, is the boiling points.
The DOT 4 has additives to raise the boiling point; therefore, it is considered high performance.

You can mix them, but doing so will lower the boiling point of the DOT 4.

I also believe, that synthetic is considered DOT 5 and is not prone to absorb water.

I do not believe these can be mixed (but the bottle/can should tell you that).

 

[Mark20]

The absorbing water part is to keep water from pooling in one spot and corroding the brake system.

 

[gmcman]

DOT 5 is a silicone-based fluid, and absolutely cannot be mixed with DOT 3&4 fluid.

DOT 5 is also not compatible with ABS systems so it's not even a possibility.

 

[n0kfb]

I am planning on useing a turkey baster to drain and then replace with new fluid. Bought some prestone synthetic brake fluid (dot 3) yesterday and it dawned on me that I not all the fluid I've seen said synthetic on the lable. Is it ok to use this even if the old fluid isn't? Or are all brake fluids synthetic and they just put it on the lable to make it seem better? Thanks

What's the point to only changing the fluid in the master cylinder reserviour? if you do this, do it right. Step one is to check the owners manual so you buy the correct fluid. Step two should be to review the process to bleed the brakes on your specific truck in a service manual. Step three might be to make certain your bleeder screws are loose and actually are not crudded up so bad they don't pass fluid.

If you are not careful, this could be a lot larger job than you had hoped.

-- Dan Meyer

 

[fishguy1123]

The fluid is dot 3, just happened to say synthetic on the lable. As far as the turkey baster method goes I figured it couldn't hurt even though it isn't a full swap/bleed. Not ready to do that till spring and for 7 bucks I did it. Thanks for all the replies.

 

[Fire06]

If you are planning to do the brake fluid flush in the spring like you mentioned presoak the bleeder nuts a few times over the winter to help in the freeing of them in the spring. Sometimes they are a real pain in the ass to brake free usually friends and familly because they never bleed their brakes or squirt them with penitrating oil to keep them from siezing

 

[fishguy1123]

Good idea, I'll do that for sure. I have had to "argue" with them on previos vehicles in the past!

 

[Fire06]

You do realize though that doing something like that takes all the fun out of it. You never know it maybe a job that must get done on the coldest wettest day of the year.

 

[fishguy1123]

You do realize though that doing something like that takes all the fun out of it. You never know it maybe a job that must get done on the coldest wettest day of the year.

That when I call the GMT back up crew. No sense in me haveing all the fun to myself!

 

[Fire06]

Sorry I think I am busy that day I think or I am busy the other day you are thinking of . Sorry I really wanted to help on that cold wet day.

 

[fishguy1123]

Dang.... and you are just around the corner from me too!

 

[Fire06]

Just around the corner a little bit

 

[91RS]

You are fine to mix the synthetic, it will not hurt anything. Also' changing the fluid in the resivor befo flushing will help with getting he fluid cleaner. If you really want it clean do that a few times in the mean time and right before you flush the system.

 

[SBUBandit]

I got a Motive Power Bleeder for Christmas from my wife, so I plan to flush my brakes in the spring. Will most likely replace it all with Valvoline or Amsoil synthetic DOT4. Any one have a rough idea how much fluid it takes on the TB to do a full flush?

 

[91RS]

I got a Motive Power Bleeder for Christmas from my wife, so I plan to flush my brakes in the spring. Will most likely replace it all with Valvoline or Amsoil synthetic DOT4. Any one have a rough idea how much fluid it takes on the TB to do a full flush?

It doesn't take much to do a flush, but I usually use at least 2 of the big bottles and empty and fill the resivor first to try and get the fluid really clean. I actually ran 3 bottles through my truck.

 

[fishguy1123]

It doesn't take much to do a flush, but I usually use at least 2 of the big bottles and empty and fill the resivor first to try and get the fluid really clean. I actually ran 3 bottles through my truck.

I used about a 1/3 of a 32 oz bottle the first time when I removed it from just the res. Figure I'll do it a couple more times before spring then do a full flush.

 

[MichEnvoyGuy]

I seem to remember there was a recommended sequence of which bleeder to open first, to flush the brake system...didnt see it posted yet. Anybody remember the sequence or have it handy to add to the thread?

 

[The_Roadie]

I found How to Bleed Brakes

Must brakes be bled in a specific order?

Bleeding is done one wheel at a time. The "old timers" will tell you to start with the wheel furthest from the master cylinder and work your way closer. Typically, this would mean RR, LR, RF, then LF. However, it doesn't really matter if you start with the front or rear wheels, since they are on separate circuits on modern cars with ABS and/or dynamic stability control systems.

 

[MichEnvoyGuy]

I found How to Bleed Brakes

Must brakes be bled in a specific order?

Bleeding is done one wheel at a time. The "old timers" will tell you to start with the wheel furthest from the master cylinder and work your way closer. Typically, this would mean RR, LR, RF, then LF. However, it doesn't really matter if you start with the front or rear wheels, since they are on separate circuits on modern cars with ABS and/or dynamic stability control systems.

Cool. The last time I flushed I think I used that sequence. I guess it doesnt really matter anyways though!

 

[Skier]

Folks,

All Brake Fluid purchased now days is synthetic.

The "glycol" based starts out with Methanol and a trace of Potassium Hydroxide. Next Ethylene Oxide and Propylene Oxide are pumped in to some specific molecular weight. Then the uncapped Hydroxyl group is capped with Methyl Chloride. Called William ether synthesis. There may also be some other newer ways to cap off the Hydroyl group.

DOT 4 is vacuum stripped to a higher boiling point than DOT 3. There are probably various additives for various reasons, rust prevention, etc.

DOT 5 is either Dimethyl Silicone or Methyl Phenyl Silicone or some blend and can only be used in older non-ABS vehicles. All rubber parts also need to be replaced.

A synthesis chemist

 

[rodehawg]

The absorbing water part is to keep water from pooling in one spot and corroding the brake system.

That doesn't sound right to me at all. Being hydroscopic, it will apsorb moisture from outside and bring it into the fluid. The more moisture in the fluid, the more chance of corrosion.

 

[tblazerdude]

Also, a sign of water in brake fluid is a greenish tint. Example, "My brake fluid was spotless but had a green tint." This means there is too high of a moisture content, and needs to be flushed and replaced. Even if you never, ever, took your master cylinder cap off, moisture will find its way in.