toolman44092

I read that DOT 5 brake fluid cannot be used in anti-lock brakes.

I also have read that some of the Forum members like sythetic brake fluid. I thought the sythetics were the DOT 5 fluids.

What's the deal? I'm doing a complete flush in the next few weeks, and I'd like to use a synthetic if I am able to. I plan to attempt a few autocross events this year, and I'd like to upgrade my brake fluid while I have the chance.

Anyone have knowledge on this?

JoeyG

I use Valvoline DOT 4 synthetic fluid. It has a higher boiling point than most. Use it in the clutch master also.

leaftye

I like the Ford Motorcraft Heavy Duty fluid. It's $3 a bottle, and has a great dry temp.

Bill Curlee

Dry boiling point is cool but, if you want brakeing performance, look for the product that has the best WET boiling point! As soon as you open the bottle it starts to absorb moisture.
Why shift to synthetic? It has it's own drawbacks! It has an affinity for air and your system may not be compatable with it. If you dont get all the other gylocal based fluid out, you can have all kinds of issues!
Some people who run synthetic get spongey brakes when they change altitude.

Just run quality DOT-4 and change it every year or every other year.

VERYSOON

Bill

I believe you are confusing synthetic with silicone. Lots of Dot 4 brake fluid is synthetic.
Castrol SRF (wet boiling point 518 degrees) and Motul RBF600 (wbp 420 degrees) and Valvoline (wbp 333 degrees) are all Dot 4. ATE super blue/type200 is a Dot 3, I believe, with wet boiling point of 392 degrees.(Probably the best bang for the buck!)

Hope this helps the original poster. (I am looking at the spec sheets for the above.)
If you will look further down the post list you will see my post inquiring about forum member use of Castrol SRF. I believe my looking into this subject is the same reason you are. Checked the autocross section, just looking for more viewers opinions.
g

Cruncher

Are you sure about the clutch? The owner's maual lists a different fluid for the clutch and I was told that there is no need to change the clutch fluid since it is in a sealed unit.

I plan on having my brake fluid flushed in the spring and will be using Castrol LMA (the $3/bottle, not the $70/bottle). LMA is the low moisture activity fluid. I have used this brand for years and never had any problems, including any excessive moisture.

MNCrystalRed2011

I use Wagner DOT 5.1 fluid. It is compatible with DOT 3 or 4, but not DOT 5 (silicone).

C66 Racing

Couple of comments.

The owners manual specifies a DOT 3 brake fluid and I know of a Z06 owner who had brake warranty work denied for running a non DOT 3 brake fluid.

That said, as long as you recognize the warranty issue, I have been running racing brake fluid since the first month I have owned my car. I ran Motul RBF 600 for years, then last season switched to Wilwood EXP 600 Plus from forum vendor Hardbar. Wilwood EXP 600 Plus is 626F dry, 417F wet. This fluid is very comparible to the Motul in performance and cost, but as far as I can tell is American made. I have been happy with it and will use it again this season.

Also, the owners manual says the clutch fluid is GM part 12345347 or equivalent DOT 3 brake fluid. I have been using the same fluid in my clutch as my brakes for years as well.

Bill Curlee

There is no way you can tell the difference between DOT-3 and DOT-4 by just looking at it. For that matter I seriously doubt it you would know if someone changed out your GM clutch fluid with brake fluid. The guy would have have to tell the tech that he changed to DOT-4 or the tech would have had to guess and asked the C5 owner in a round about way if DOT-4 was in the system.

There is know way of knowing the difference just by looking at it.

BC

Cruncher

I know there is a part number for the clutch fluid. However, the mechanic had told me that the clutch fluid does not need to be flushed since it is in a sealed reservoir. I was also told that if I wanted the clutch fluid flushed, it would very expensive/time consuming.

Do you change your clutch fluid because you race and also, how hard/time consuming is it to do? In the latest issue of Corvette, there was an article about changing fluids. I don't recall reading about flusihng the clutch fluid, but I do remember the article stating that your brake fluid should be changed. Any insight? Thanks.

Cruncher

Maybe the person that Subdriver knew was using the "Blue" stuff...itsn't that DOT-4?

Bill Curlee

Wagner DOT 5.1 fluid. It is compatible with DOT 3 or 4, but not DOT 5 (silicone).


Woops Silicone--Synthetic,, made a quick slip of the fingers,, SORRY about that!

DOT-4 is regular old every day standard brake fluid. There are manufactures that make Synthetic DOT-4 (Valvoline SynPower). Synthetic DOT-4 will work fine.

Like I said previously, minimum wet boiling point is what you need to look at.

As long as you do NOT use SILICONE fluid (DOT-5) in your system, you will be fine.

gmblack3

Tell your mechanic to get off the pipe!

Your brake fluid is in a sealed reservoir too.

Yes the clutch is a major PITA to bleed:

http://www.97vette.com/howto/clutchbleed/index.html

You can remove all the fluid you can from your clutch reservior with a syringe or baster, wipe out the inside with lint-free paper towel, then refill to the center of the reservoir with your brake fluid. If your fluid was very dirty you will see the dirty fluid work its way back to the top. So do this every 2 weeks for a daily driver till the fluid is clean.

Best bet would be a full flush, the remove/refill every few months.

AU N EGL

was using Super Blue but boiled it too many times ( I am a late braker ) now use Castrol SRF and in the pick-up I use Ford HD brake fluid for towing the trailer.

IMHO check the color of your brake fluid. It should be a nice gold color ( ATE-Super Blue excluded) if your brake fluid is brown/ black and opaque, time to change it. Closed system or not Brake fluid is hydoscopic, it absobes water. a 2 or 3% water absorption into the brake fluid will decress your braking abilites up to 25%. ie 25% longer to stop

Brake fluid that is in your car or truck for a year is saturated 3% with water. time to change. Bleeding brakes is not hard to do at all.

Just more time for you to become intamate with your corvette

GUSTO14

DOT 5 is Silicone Brake Fluid. It is the only silicone fluid. Not to be confused with synthetic fluids.

DOT 5 is non-hydroscopic, so it is ideal for use in vehicles ("classics") that are not driven frequently. It also works well in vehicles that do not experience extraordinarily high brake temperatures. (I used it for low speed autocrossing for 3 years and never had a problem.)

Silicone brake fluid is not suited for racing because it will expand when heated excessively. In a sealed system this can lead to brake lock-up, so it is not recommended for those applications.

Silicone also aerates much easier than petroleum based brake fluids, so care must be taken when bleeding the brakes. (Shake a bottle of hydraulic brake fluid and a bottle of silicone. The silicone will retain bubbles much longer than the hydraulic.) This simply means don't pump the brakes rapidly while you are bleeding them to minimize the amount of bleeding you have to do. This is also the reason that it can be a problem with ABS.

I have used silicone brake fluid in a multitude of vehicles and never had a problem with it, from Corvettes to Harleys. (I have not used it with an ABS system yet but will under the right circumstances.)

If you have a vehicle that sees limited road time and want to reduce upkeep, it can save you a lot of time and money. If this is not an issue with you, don't even worry about silicone brake fluid as it costs about double what DOT 3 fluid costs. Also if you're building a race car I would not recommend using it.

Silicone is in fact compatible with other brake fluids, but does retain its characteristics. I.E. it expands when heated and aerates more easily. The main purpose in completely purging the brake system before using silicone is to remove the hydraulic brake fluid in order to gain the maximum benefit from the silicone. Namely to remove the number one source of corrosion in an automobile brake system. Oh yea, unlike hydraulic brake fluids, it will not damage paint…

GUSTO

VetteDrmr

More important to what brand DOT 3, 4, or 3/4 you use for autocrossing is that it's fresh. I flush mine once a year, and bleed them every other event. Running your car on a track continuously puts a lot more heat into the brakes than autocross, but you still need to take care of it.

HTH, and have a good one,
Mike

toolman44092

Thanks for all the input.

Great info.

C66 Racing

Cruncher, you're exactly right. He had ATE Super Blue (a DOT 4 fluid) so it was pretty much a no brainer for the dealer to determine it wasn't stock.

I do try to keep my clutch fluid bled because of racing, but it was more of an attempt to stave off the dreaded clutch pedal sticking to the floor issue than keep the clutch fluid clean. From my understanding of this issue, air gets into the hydraulic lines due to minor vibration of the plates which allows air past the seal on the actuator. When air gets into the lines there is reduced hydrualic pressure to push the pedal back up. Early in the 2004 season I started to notice my clutch pedal wasn't returning as fast on rapid downshifts (such as 5-4-3 at the end of a straight). I attemped to stave off this problem as long as possible with frequent bleeds. When I had my motor out for a timing chain repair, I ended up putting in a whole new clutch just because it was easy to do with the motor out of the car.

Bleeding the clutch is a PITA. The link provided by gmblack3 shows the process in all its gory details.

I highly suggest adding an extension line like the one LAPD sells if you have the opportunity. This line brings the bleed point up to the reservoir which makes bleeding the clutch a 2 minute job instead of a 3 hour ordeal.

The turkey baster method is an easy way to keep your fluid clean. You will likely need to suck it out and replace it half a dozen times before it starts to stay clean. But, this won't get air out of the lines like a bleed will.

Wait, shouldn't we be debating synthetic lubricants?

Cruncher

Subdriver,

Do you have a link for that LAPD extension? I'd like to see what it is and if it turns a 3-hour job into a 2-minute job, I'd get it yesterday. For the 2-minute job, I am sure that the dealer will charge me one hour.
The mechanic has already told me that he does not normally bleed the clutch fluid...he said it was in a sealed reservoir. Now that I know it is such a PITA, I know why the mechanic said he doesn't bleed the fluid. If the extenstion works, I will get it. I like to keep all my fluids clean and brake fluid absorbs moisture. However, I know people that have 10 year old cars and have never changed their brake fluid. Also, I used to use Castrol LMA (made by Girling(?))....I know of only one local place that still carries it.....I guess I will change to Valvoline since I don't think that the Castrol would be "fresh"...I think there is a 2-year shelf-life for unopened bottles. Thanks.

C66 Racing

Cruncher,
Here you go:
http://www.thelapd.com/Merchant2/mer...e_Code=thelapd

This line basically just extends the bleed location to up in the engine bay where you can reach it and bleed the clutch as easily as a brake. More easily actually since you don't have to do any prep work like take off a wheel.

Only problem is that putting it on is as hard as bleeding the clutch as getting access to the stock bleed nipple is still a PITA.