Brake Fluid for Silverado

[Rhymingmechanic]

I'm getting ready to flush the brake system on my 2001 Silverado. I just got a set of Speed Bleeders, but have not been able to decide on a fluid.

I have searched the posts on this forum, and there seems to be some disagreement about using DOT 4 in a system that calls for DOT 3--some say 4 could absorb more water or harm components, and others say they are completely compatible. The filler cap and manual both specify DOT 3--"Delco Supreme 11" or equivalent.

So, can anybody clarify the 3 vs 4 issue for this vehicle? I can get Castrol LMA 3/4, which gets good reviews here. Next to it at Pep Boys is Gunk Premium DOT 3, which claims a 450* dry boiling point, but does not mention a wet point higher than DOT 3 specs. How does the Delco fluid compare to those and other fluids? I've never seen the Delco specs.

Thanks for any comments.

 

[DJ]

Just to add more confusion, over on the Impala board the two most common recommendations are ATE blue and Valvoline synthetic. The Valvoline being much easier to find and cheaper, as well as being just about as good as the other stuff which is highend I guess you find it at German garages.

 

[seotaji]

quote:

---

which is highend I guess you find it at German garages.

---

i see it more at race shops, but yep, some geman garages stock it too.

quote:

---

there seems to be some disagreement about using DOT 4 in a system that calls for DOT 3--some say 4 could absorb more water or harm components, and others say they are completely compatible. The filler cap and manual both specify DOT 3--"Delco Supreme 11" or equivalent.

---

that is absolutely false in reference to Castrol LMA DOT 3/4. the whole point of LMA is just that, low moisture absorbtion compared to other fluids.

the gunk fluid with the high dry boiling point means nothing, as brake fluid starts to absorb moisture the minute you open the container. get something with a high wet boiling point and you'll be good to go.

most, if not all dot3/4 fluids are compatible, if they aren't it's listed on the label. i wouldn't use a dot5 though, since it is def. not compatible.

i'd use whatever you felt like using. higher quality fluids are usually best. i'd always reccomend to flush every year though.

 

[par]

Since you have the speed bleeders, I would suggest buying a discount brake fluid (dot 3 or 4; it really doesn't matter) and then changing the brake fluid every year.

 

[Ken2]

DOT4 has a slightly different chemical composition than DOT3 has...that's why it has different characteristics.

There is a very slight chance that some of the rubber-like parts of your brake system will react poorly with DOT4. I've never had it happen, nor have I ever heard of a problem.

Probably the best brake fluid for the money seems to the the Valvoline Synpower. By the way, all brake fluid is synthetic.


Ken

 

[par]

I you bled/changed the fluid every year in a street vehicle, then does it really matter what brand of brake fluid you use?

 

[wn1998]

I really think a brake fluid flush every year is very very overkill. I would say 99.5% of people in america don't ever flush their brake fluid even once in the lifetime of their vehicle. I have a 92 cavalier with 190k that has probably the same factory fill brake fluid with only 2 or 3 top offs and I have no problems at all. I can see how this might be different it a high powered sports car, but an average daily driver probably doesn't need it. If you do decide to do it once every 5 years is more than you need.

 

[XS650]

quote:

---

Originally posted by seotaji:

most, if not all dot3/4 fluids are compatible, if they aren't it's listed on the label. i wouldn't use a dot5 though, since it is def. not compatible.

---

I'm pretty sure it is a requirement that all DOT 3/4 fluids be fully compatible.

Someplace on the web there is a table that shows how much several different brands of fluid attract water. For most of us, that's more important than small differeneces in wet or dry boiling points. Unfortunately, I can't find the web page.

I do remember that the Valvoline Syn was one of the good ones and that one of the other brands with the highest boiling point sucked up water faster than most.

 

[Ken2]

The brake fluids are compatible, the there is a very small chance that an elastomer in the brake system is not.

DOT3, DOT4, and the higher boiling point stuff sometimes called DOT4+ or DOT5.1 are all compatible glycol ether compounds. DOT5 is the totally incompatible silicone product.

Isn't Ford DOT3 the brake fluid with the very high dry boiling point and lower wet boiling point? I think it is popular with some racers, but they change brake fluid often.


Ken

 

[labman]

Frankly the safest thing to do, is to leave the factory fill in it, as GM recommends. Long before it causes any problems, you will be losing most of it when you eventually renew the worn, aged, maybe damaged rubber parts rebuilding or replacing the calipers. I haven't had any problems at that time adding Prestone DOT 4 to the original GM fluid. Changing fluid neither delays or substitutes for preventative maintenance.

Otherwise you leave your self open to iatrogenic* problems. Doing unneeded work can cause more problems than it solves.

*iatrogenic (iatro- + Gr. gennan to produce) resulting from the activity of physicians. Originally applied to disorders induced in the patient by autosuggestion based on the physician's examination, manner, or discussion, the term is now applied to any adverse condition in a patient occurring as the result of treatment by a physician or surgeon, especially to infections acquired by the patient during the course of treatment. Cf. nosocomial.

 

[MolaKule]

quote:

---

*iatrogenic

---

Could one have a cryogenic, iatrogenic, anthromophoric situation as well?

Good one labman. Even I learned a new word today.

 

[Big Jim]

I use Valvoline synpower and change it annually. I believe in agressive maintenance.

I have seen too many old brake systems (and clutch hydraulic systems as well) that still have the original fluid long after the fluid turned black. You should see what it does to the internal hydraulic parts. All of which can be avoided by ocassionally changing brake fluid.

How often should brake fluid be changed? The industry standard is every 3 to 4 years for DOT 3 and every 2 years for DOT 4 under normal driving conditions. More often if you drive hard.

By the way, the real damage from old fluid is often not as evident in the calipers/wheel cylinders/master cylinders as it is in the ABS HCU (hydraulic control unit).

For normal or even high performance street use, either Castrol LMA or Valvoline Synpower are exceptional fluids. ATE Super Blue is even better, but probably a bit of an overkill unless you are an agressive racer.

 

[Rhymingmechanic]

Thanks to everyone for the replies. I just finished the flush, staying with DOT 3 fluid (Prestone) to be sure of compatibility with the system.

I was checking under the hood recently, and realized the master cylinder cap was not fully closed. I can't remember ever opening it, so the cap has either always been half-closed, or it was disturbed at a shop sometime in the last 3 years. Anyway, the fluid was dark and I was concerned about moisture contamination.

The rear bleeder screws had some white corrosion on the ends--maybe because the rear calipers are aluminum? Otherwise, everything looked fine. The Speed Bleeders (Russell brand, from Summit Racing) worked great, and the pedal feels quite a bit firmer now.

Big Jim, you said DOT 4 should be changed more often than 3. I'm still curious about the differences, and why a newer vehicle would call for an "older" fluid instead of the latest spec.

Thanks again for everybody's input.

 

[Ken2]

quote:

---

Originally posted by labman:
Frankly the safest thing to do, is to leave the factory fill in it, as GM recommends. Long before it causes any problems, you will be losing most of it when you eventually renew the worn, aged, maybe damaged rubber parts rebuilding or replacing the calipers. I haven't had any problems at that time adding Prestone DOT 4 to the original GM fluid. Changing fluid neither delays or substitutes for preventative maintenance.

---

Hmmm. I don't agree. One friend had total brake failure when his old brake fluid boiled during heavy braking. Fortunately, the only casualty was his shorts. Another case was in the local newspapers a few years ago where brakes failed due to the fluid overheating and flashing to vapor, and a child was run over and died.

I feel that changing brake fluid IS preventive maintenance.


Ken

 

[Big Jim]

quote:

---

Originally posted by Rhymingmechanic:

Big Jim, you said DOT 4 should be changed more often than 3. I'm still curious about the differences, and why a newer vehicle would call for an "older" fluid instead of the latest spec.

Thanks again for everybody's input.

---

Whatever it is that raises the boiling point in the formulation is also more hydroscopic. The trade off of raising the boiling point in the fluid is that it will require changing more often because it has a greater affinity for moisture.

It isn't really so much a matter of being an older spec as it is being a different spec. The Europeans tend to spec DOT 4 with it's higher boiling point I suspect because they build for use on the Autobahn where brakes are even more critical than they are here.

 

[Rat407]

I have an 02 silverado and went with the Super Blue ATE. I do most of my purchases online, I live in the sticks, plus the blue color made it easy to tell when it was 100% through the lines. I also used it in my 65 Impala which sits a lot more than I like and it was recommended since it has a lower moisture absorbtion rating than most.

Sorry for spelling, they really need spell check on these forums.

 

[wtd]

I have a 98 silverado and I flush the brake fluid about every two years when its time for new brake pads. I use Delco supreme from the dealer. So far no problems in 71,000 miles.

Wayne

 

[labman]

quote:

---

Originally posted by wtd:
I have a 98 silverado and I flush the brake fluid about every two years when its time for new brake pads. I use Delco supreme from the dealer. So far no problems in 71,000 miles.

Wayne

---

--

I strongly suspect the ones with the original factory fill haven't had any brake fluid problems either. If you really want to avoid problems, you should consider replacing the aged, worn rubber parts in the calipers next pad change.