First TECHNICAL ISSUE Post On The New Board

[Chuck S.]

Edit: Actually, this is the SECOND Technical Issue posted to the new board...Tyler Townsley had the FIRST. But...It has been a learning experience...I found out you can not edit the Title line in the index listing; only the first post will be edited.

Let's see if the California guys are up yet...

Question: Valvoline "Synthetic" brake fluid (Aren't ALL brake fluids synthetic? )...When Valvoline says that their synthetic brake fluid exceeds DOT 3 AND DOT 4 requirements, what do they mean? Are they saying that it continues to perform satisfactorily at temperatures exceeding those DOT specifications? Can this brake fluid be used in systems like ABS that are specified to use ONLY DOT 3 fluid?

[Michael W.]

Re: First TECHNICAL ISSUE Response On The New Board

Real Corvettes don't use ABS.

[Chuck S.]

Re: First TECHNICAL ISSUE Response On The New Board

There, fixed it...Real NCRS Corvettes most certainly do have ABS!

Keep it on topic there, Mikey, or I'll have to "dock" your rep! HaHaHa! Man, John given us some really powerful tools here...Do you realize how this would have been back in old DB days with this software?

[Duke W.]

Re: First TECHNICAL ISSUE Post On The New Board

You are correct, Chuck. All brake fluids are "synthetic" because they are all "synthesied" in a complex petrochemical process from petroleum derived feedstocks.

"Synthetic" has become just another marketing buzzword. Antifreeze is "synthetic" and even the least expensive motor oils are blended with some hydroprocessed stock, which is considered to be "synthetic". A least a small amount of hydroprocessed stocks are required to meet today's tough motor oil oxidation requirements.

DOT 3 and 4 brake fluids are polyglycol based and completely compatible with each other. The difference is that DOT 4 has higher "dry" and "wet" minimum boiling point specifications. The wet boiling point is important because polyglycol brake fluids readily absorb moisture, which reduces the boiling point.

From my research over the years it also appears that DOT 4 may be more resistant to moisture absorbtion and/or have a better corrosion inhibitor package to help prevent corrosion.

I use DOT 4 in my cars, and the two most common brands are the Valvoline product you mentioned and Castro LMA. I am indifferent to them and buy what ever is most readily available or the lowest cost if both are on the shelf.

Duke

[Chuck S.]

Re: First TECHNICAL ISSUE Post On The New Board

You are correct, Chuck. All brake fluids are "synthetic" because they are all "synthesied" in a complex petrochemical process from petroleum derived feedstocks.

"Synthetic" has become just another marketing buzzword. Antifreeze is "synthetic" and even the least expensive motor oils are blended with some hydroprocessed stock, which is considered to be "synthetic". A least a small amount of hydroprocessed stocks are required to meet today's tough motor oil oxidation requirements.

DOT 3 and 4 brake fluids are polyglycol based and completely compatible with each other. The difference is that DOT 4 has higher "dry" and "wet" minimum boiling point specifications. The wet boiling point is important because polyglycol brake fluids readily absorb moisture, which reduces the boiling point.

From my research over the years it also appears that DOT 4 may be more resistant to moisture absorbtion and/or have a better corrosion inhibitor package to help prevent corrosion.

I use DOT 4 in my cars, and the two most common brands are the Valvoline product you mentioned and Castro LMA. I am indifferent to them and buy what ever is most readily available or the lowest cost if both are on the shelf.

Duke

Thanks, Duke...I was hoping you would come through for me.

Why do you think that OEM owner manuals are so adamant about using ONLY DOT3 for ABS?...What is it about DOT4 they don't like in ABS? It seems like higher wet and dry boiling points, and better resistance to water absorption would be good things for any brake system.

[Duke W.]

Re: First TECHNICAL ISSUE Post On The New Board

It depends what owner's manual you are looking at. My Mercedes Benz owner's manual specifies DOT 4.

Most GM owner's manuals specify DOT 3 - maybe because they feel it's adequate given our lower speed limits compared to the unrestricted autobahns, which can heat up brake fluid very rapidly when a driver has to brake hard from near top speed.

For current Corvettes GM specifies a "special" fluid for the clutch release system, and my understanding is that this is nothing more than DOT 4 because they still use DOT 3 in the brake system.

In normal driving the clutch system of new Corvettes sees higher temperatrues than the brake system because it's all enclosed in the center tunnel (which also makes flushing the clutch system difficult because the bottom tunnel member must be removed to access the slave cylinder).

This was causing problems with the clutch release system, so GM upgraded the clutch fluid to DOT 4.

Duke

[Chuck S.]

Re: First TECHNICAL ISSUE Post On The New Board

For current Corvettes GM specifies a "special" fluid for the clutch release system, and my understanding is that this is nothing more than DOT 4 because they still use DOT 3 in the brake system.

Yeah, those GM manuals give you a part number for every fluid, well, except for gasoline. It would really gall me to find out I had bought Prestone DOT 3 fluid in a GM bottle for 4X as much dough.

Being unable to change the clutch fluid except with a turkey baster is a poor design...you would think they would have changed that by now, especially in view of the clutch problems racers have had.

Thanks for your advice...I'll run down to Pepboys and get another quart of that Valvoline "Synthetic". It's been a couple of years now, and it's time to change the brake and clutch fluid.

[Duke W.]

Re: First TECHNICAL ISSUE Post On The New Board

IIRC I've seen an "extension pipe" for C5/6. It threads into the bleed valve bore on the slave cylinder and has a bleed valve at the top end that moves the bleed valve to a more convenient location that can be accessed without removing the bottom tunnel panel.

AFAIK GM has never recommended brake or clutch fluid changes, so they didn't pay any attention to this maintenance job.

Never changing these fluids is okay for a typical first owner, who will probably not suffer any consequences if he sells the car within five or six years, but downstream a long time original owner or subsequent owner will have to pay a hefty price to rebuilt hydraulic components due to lack of fluid changes.

Eventually, absorbed water will corrode the system internally. Most long time disk brake C2 owners know this all too well.

When I did a brake upgrade on my Cosworth Vega in 1981 I found corrosion in the rear wheel cylinders. At that point I got "religion" and put all my cars on a biennial brake fluid change schedule. Since that time I have never had to rebuild a hydraulic system component on the CV or my '88 and '91 vintage cars and '83 vintage motorcycle.

My SWC has silicone fluid because when I completely disassembled the system and started with everything including the steel lines clean and dry, it was a good time to upgrade to silicone. I've not switched to silicon on any of the other cars because I've never taken the brake systems completely down and purged every trace of the glycol fluid, so I just do the maintenance.

The '88 Merc is also not a good candidate for silicone since it has ABS.

Duke

[Terry M.]

Re: First TECHNICAL ISSUE Post On The New Board

The C6 section of CF has a lot of good info (most of it posted by someone with the handle RANGER) about the fluid issues of the clutch release system on the C6. I have prowled his site a bunch, even before I got the new car.
I got some of the DOT 4 GM fluid just for the clutch system. It is the first brake fluid I have seen in metal cans, but I am told it is being changed to the ubiquitous plastic containers. The manufacturer is on tags attached to the contains, and if you want to know I'll go to the garage tomorrow and post the name.
I checked at Bowing Green when I was there, and they are currently using DOT3 for the brakes and DOT4 in the clutch system. The DOT3 is delivered in carboys about four foot cubed.

[Stephen B.]

Re: First TECHNICAL ISSUE Post On The New Board

I've used the Valvoline Full Synthetic Brake Fluid in my '70 Corvette and '86 Corvette with ABS brakes with no problems.

[Clem Z.]

Re: First TECHNICAL ISSUE Post On The New Board

IIRC I've seen an "extension pipe" for C5/6. It threads into the bleed valve bore on the slave cylinder and has a bleed valve at the top end that moves the bleed valve to a more convenient location that can be accessed without removing the bottom tunnel panel.

AFAIK GM has never recommended brake or clutch fluid changes, so they didn't pay any attention to this maintenance job.

Never changing these fluids is okay for a typical first owner, who will probably not suffer any consequences if he sells the car within five or six years, but downstream a long time original owner or subsequent owner will have to pay a hefty price to rebuilt hydraulic components due to lack of fluid changes.

Eventually, absorbed water will corrode the system internally. Most long time disk brake C2 owners know this all too well.

When I did a brake upgrade on my Cosworth Vega in 1981 I found corrosion in the rear wheel cylinders. At that point I got "religion" and put all my cars on a biennial brake fluid change schedule. Since that time I have never had to rebuild a hydraulic system component on the CV or my '88 and '91 vintage cars and '83 vintage motorcycle.

My SWC has silicone fluid because when I completely disassembled the system and started with everything including the steel lines clean and dry, it was a good time to upgrade to silicone. I've not switched to silicon on any of the other cars because I've never taken the brake systems completely down and purged every trace of the glycol fluid, so I just do the maintenance.

The '88 Merc is also not a good candidate for silicone since it has ABS.

Duke

GM says change the fluid in the corvette hyd clutch system every 2 years and NEVER open the cap to check the fluid level just looks thru the plastic MC because every time you open it you let in moisture.
88958860, 88901244 in Canada, is a DOT 4 specific fluid for use in clutch hydraulic systems.

This is recommended for ALL clutch systems, as this is a new part number.

However, most owners and technicians are not aware that you are to inspect clutch fluid level by looking VISUALLY at the side of the reservoir, NOT OPENING THE CAP!!!!!! This will allow moisture in the system. Simply look at the side of the reservoir to determine fluid level.

This fluid has a 2 week shelf life when initially opened. So, in that case, once opened, the bottle should be discarded after the 2 week time frame.

If you have an intermittant sticking condition, it might be recommended to flush the clutch fluid with this part number and reevaluate the condition.

To provide the best clutch operation, it is recommended to change the clutch fluid every 2 calendar years.

GM will be updating the scheduled maintenance in the future owners manual and service information for technicians.

[Duke W.]

Re: First TECHNICAL ISSUE Post On The New Board

Valvoline "Synthetic" is a DOT 4, so it's okay for ABS. DOT 5 Silicone fluid does not work well in many ABS systems. The high frequency vibration when ABS is engaged can cause dissolved air to come out of solution.

Duke

[Duke W.]

Re: First TECHNICAL ISSUE Post On The New Board

Well, I'm glad they finally got with the program. Now the question is are they going to make it any easier to flush the C6 clutch system with their own extension pipe so the bottom of the tunnel doesn't have to be removed, which I think has over 20 small cap screws.

Translucent plastic brake and clutch reservoirs have been around at least 20 years. I thought most people had figured out that all you have to do is look at the level of the fluid relative to the "MAX" and "MIN" hash marks. It's a lot easier and more accurate than removing the cap and peering down.

Of course, my fluid is alway so clean that I have to get in the right light to see the level. Typical cars with fluid the color of day-old coffee are easy.

Duke

[Dennis C.]

Clem - Very pleased to see you on board...

I was afraid you might be lost in the past... Best, Dennis

[Chuck S.]

Re: First TECHNICAL ISSUE Post On The New Board

...Now the question is are they going to make it any easier to flush the C6 clutch system with their own extension pipe so the bottom of the tunnel doesn't have to be removed, which I think has over 20 small cap screws...

Even the installation of the aftermarket extension pipe is a project for a boring rainy day...Correct me if I'm wrong, but I think you have to remove that tunnel cover just to install the extension pipe to expedite FUTURE flushing. Until I run out of projects, I'm thinking...turkey baster! Even if the thought of doing a "half-***ed" job does bother me.