VinceBlack

Damn, I just did the Ranger method using synthetic DOT 4. Is the synthetic going to ruin anything?? It took me 9 times to get the fluid clear

Foosh

You're not supposed to mix glycol-based standard brake fluid with silicon-based synthetic. The link below is what GM puts in at the factory, and it is not labeled synthetic.

All the recommendations I've read are multiple complete flushes before switching. There are upsides and downsides to each. Glycol-based absorbs water, but silicon-based absorbs air, sometimes resulting in a mushier brake pedal. I don't know what the implication is for a clutch system.

VinceBlack

Ok, thank you Foosh. Do you think since I've already done the Ranger method a total of nine times with the synthetic it would be safe to drain the reservoir and add the non-synthetic? Would I have to do the Ranger method again to clear the synthetic stuff out?

Foosh

I wish I could answer your question, but I've never run across this issue before. I'm sure it's been done by other people. It's quite possible that in the clutch reservoir it doesn't make much difference, and it's not the potential safety hazard it would be in a brake system.

VinceBlack

Foosh, briefly spoke to the gentleman who used to worked on my old Z06. He said it's nothing to worry about, just suck the synthetic out of the reservoir and replace with non-synthetic. He actually though leaving the synthetic in wouldn't hurt anything but I didn't want to take a chance.

As far as the oil level goes, I added a quart and took it back out until the engine reached temp, came back and it was still a tad below the min level. So I added 3/4 quart and called it good. Foosh, many thanks to you and everyone else on this thread who helped me today!

pickleseimer

Hmmmm....here is some information on brake fluids you may find informative.

And an item from BobIsTheOilGuy site on DOT-4 vs Super DOT-4:

'Super DOT4 has a dry boiling point that exceeds the minimum requirement for DOT5.1, but the wet boiling point does not meet the minimum requirement for 5.1. It is basically racing brake fluid made to be flushed often.'

Then, this from the Editor of Brake & Front End Magazine:

**************************************** **************************************** *****************
By Andrew Markel
Editor, Brake & Front End


1. What are the fundamental differences between synthetic fluid and conventional DOT 3 and 4?
Simple, it all comes down to the base stock. Both synthetic and conventional brake fluids start from the same “polyethylene glycol” stock. But to make synthetic brake fluid the manufacturer will “synthesize” the
original base stock and make the molecules better and more consistent.

They could make the chains longer or add other molecules to enhance the performance. Almost every synthetic brake fluid manufacturer does it differently. To the base stock they add the additive package. This is a mixture of anti-corrosion, anti-foaming and other secret chemicals that give the fluid the desired performance characteristics for operation in vehicles. DOT 5.1 is a high-performance certification (higher temps than DOT 5). To meet the performance criteria, it takes a synthetic or really good conventional base stock. Silicone is a synthetic substance. But don’t confuse Dot 5 with synthetic polyethylene glycol-based fluids like DOT 5.1.

2. What is the compatibility between synthetics and conventional DOT 3 and 4 in most vehicles? Is a complete flush with new rubber a better choice? Is there any chance of seal swelling or disintegration in older vehicles, say from the 1930s, 1940s or even in the 1960s?

All DOT 3, 4 and 5.1 brake fluids are compatible with each other and with all systems. All polyethylene glycol-based fluids will not harm healthy rubber parts. Also, the additive packages will not damage or distort any rubber parts. Even an older rubber part that has a high concentration of natural rubber, will not be damaged by new DOT-rated brake fluids. What kills rubber parts is when the additive package breaks down.

The additive package controls the pH of the fluid and the viscosity. If the brake fluid becomes unable to control the pH or other corrosive elements, the rubber and metal parts will deteriorate over time.

If you have an older vehicle and are worried about boiling the fluid, use DOT 4 or 5.1 brake fluid.

3. Can synthetics be mixed where DOT 5 silicone was used or is it recommended that the rubber be replaced when changing back?

Silicone is an inert substance. Technically it should not damage the rubber parts. Polyethylene glycol based fluids (conventional or synthetic) will not mix with silicone fluid (DOT 5). It will lump together somewhere in the system. Also, they will not react when it is mixed. So, if you perform a good flush, the rubber parts and the system should be OK.

4. Now that it is known that copper contamination is the main reason that brake fluids degrade, what property do synthetics have to address this problem?

Copper comes from the copper brazing in the walls of the hard brake lines. copper can be a problem for ABS and some valving. But it is an indicator of the state of the brake fluid. The more copper that is present, the greater the chance of corrosion happening in the system. When there is corrosion, it is a sign that the brake fluid’s anti-corrosion additives are depleted. If your base stock and additives are of higher quality, chances are that they will not break down as easily as low-quality ingredients.

5. Compared to conventional fluid, what life span can be expected from synthetics?
In my opinion, it is about the same. Synthetic fluid might be able to last a little longer because the fluid can absorb more water before the fluid drops below a critical boiling point. But it is the additive package and environment that has the greatest impact on life span, no matter what type of base stock.

6. Do synthetic fluids provide a better pedal feel?
Some very high-end synthetic DOT 4 and 5.1 synthetic fluids can give a stiffer pedal. But, it is so small of a difference that only the very, very, very best drivers can feel it. It is mostly in their head. Some silicone-based fluids can give a softer pedal because it is more compressible than glycol-based fluids. But, some high-tech silicone ester-based stuff that some race teams use is less compressible than glycol-based fluids. But, this stuff can run $90 a liter! Also, it does not have some critical corrosion inhibitors and is not DOT certified.

DOT 5 brake fluids still have their place. Owners of show cars can use the fluid if they are concerned about damage to the paint.

JerryU

Hmm, not sure I would just leave in the silicone DOT 5, it could effect clutch performance. It is compressible, which is a key reason not to use it for brakes.

My ProStreet Rod chassis, built by TCI, came with a quart of silicone brake fluid. Used it and peddle was spongy after many brake bleeds. In a car with ABS that slightly higher compressibility is enough to mess up that rapidly activating system. Talked with TCI and they said they supply that for Show cars since the DOT 5 will not eat paint! My chassis is painted the same colors as the car but I do drive it!

The recommended proceedure to replace DOT 5 with DOT 3/4 fluid was to drain the system and pump through alcohol, then blow out the alcohol with compressed air. Meant disconnecting all the brake lines, proportioning and check valves.

I decided to use about a quart of DOT 3 and bleed the brakes many times using a hand vacuum pump brake bleed device. PIA but has worked fine for ~15 years! I do empty and refill the brake fluid about every 2 years. Might as well as I have to remove the driver's seat to access!

DOT 5 may be OK, not sure how much compressibility is an issue with the clutch. Also not sure about issues with seals, especially the one at the clutch rod. Silicone is inert but not sure that is what that seal needs. Recall when synthetic engine oil first came out it caused some seal issues as they were supposed to swell slightly. The oil companies added whatever to have that occur!

Believe I would use the Range Method as described by Foosh as that should leave 95+% of the DOT 5. I'd repeat in 6 months.

VinceBlack

I was never using DOT 5. It was synthetic DOT 4. I did the Ranger method 9 times with the synthetic DOT 4 until the fluid was clean. It was at that point Foosh informed me that I should have been using non-synthetic DOT 4. So I sucked the synthetic DOT 4 out of the reservoir, wiped inside with no-lint cloth, and replaced with non-synthetic DOT 4.

JerryU

^^^
Oh well for anyone considering DOT 5 supplied the reasons why not!

Foosh

Great! I'm sure you're fine. It's no big deal to run a quart low in normal driving.

As for the compatibility between synthetic and standard DOT 4, the info in post #26 is pretty compelling that they are. Sucking out the small amount in the clutch fluid reservoir wouldn't make much difference since you've already mixed the two up with 9 exchanges of reservoir fluid.

However, based upon that post, it sounds as if all DOT 4 is compatible, so I'm pretty sure you're good. I learned something tonight.

madrob2020

Read the OM & I think you'll find it states something such as, if your clutch fluid is low, you have a problem. Clutch fluid doesn't get "used up" as oil does. If it gets below the bottom intake hole you will get air into the system-bad.

Patman

It's funny how many people won't trust an electronic method of checking oil level, but yet we completely trust our gauges to tell us our fuel level, oil pressure, oil temperature, etc. Porsche has been using an oil level gauge on it's dash in the 911 since the 80s (maybe longer?)

VinceBlack

Madrob, that's what I'm afraid of. I'm not a mechanic by any means but I know enough to know that the fluid in the clutch reservoir simply doesn't disappear. The car only has 10,800 miles on the odometer. I purchased this vehicle from Carmax 7 days ago and had a very frank conversation with the sales manager today...asking him how they could release a vehicle to a customer with barely any fluid in the clutch reservoir and 2.5 quarts low on oil. They tout a 121-point inspection prior to sale; total BS. They agreed to pay for the vehicle to get inspected by my local Chevy dealership this Friday so we'll see what happens.

Foosh

Yes, it is funny. You clipped my post in quoting, but as I said, I'm OK w/ the electronic oil quantity system.

I simply pointed out a lot of people would rather have the dipstick as well as backup. GM likely knows their (old-school) customer base as well, and the fact that a much higher percentage would complain about no dip stick, since even the more technology-accepting crowds complain about it on other brands.

Vince, was the reservoir totally dry? Was the clutch operating normally? Did you notice any leaks under the car? Is the level staying the same since you did the Ranger method and topped it off?

There's only about a shot glass in there, and there are other explanations for it being low. For example, someone could have left the cap off and pumped the clutch at some point.

On the oil issue, I believe CarMax changes the oil on all their vehicles before sale. It wouldn't surprise me if they didn't know the difference between a dry and wet sump LT1, and the fact that the dry sump needs at least 2 more quarts.

At any rate, it's good you're getting it checked out.

VinceBlack

The reservoir wasn't completely dry, I'd say there was roughly an 8th of an inch there. There were no leaks under the car...I haven't seen anything on my garage floor. I will check the fluid level tonight to ensure it's still full. Looking back, I think the clutch was operating normally, maybe a little rough. Since I didn't realize the fluid was low I probably wasn't paying close enough attention...any oddities I think I would have simply attributed to me getting used to a new clutch. However, now I'm very cognizant of how the clutch operates and it's smooth as silk. Hopefully there was no long term damage done. It scares me to think about how long the vehicle was operating with little to no clutch fluid (before I purchased it).

After speaking to the CarMax sales manager, it's apparent that no inspection was done. I think they figured the CarMax at the previous location (Las Palmas, Ca where I had it transferred from) did the inspection. The vehicle has no GM/Chevy service history which tells me the previous owner did not take advantage of the 2 free Customer Care oil changes....he refused, or didn't know how, to care for this vehicle which is a shame. CarMax did make sure to do one thing though, they sprayed the engine with this crap engine degreaser which made the engine/cabin smell like rubber at operating temperatures. It's slowly going away but it's irritating to say the least.

Foosh

Vince,

Just because the reservoir was almost empty doesn't mean there wasn't plenty of clutch fluid still in the system. As I said, the reservoir in the engine bay only holds roughly 1 oz. If it was nearly empty your clutch wouldn't have worked at all.

VinceBlack

Very true, I have to remember the system would still hold a significant amount of fluid even if the reservoir is nearly empty.

VinceBlack

Just got the Vette back from the dealer. Their used car inspection revealed a very small leak in a hose going to/from the dry sump oil system. Technician said he's never had to replace one before. Parts are on order and scheduled to go back next Wednesday. Odd because I have not seen any oil on my garage floor. Glad the issue was caught before it became a huge problem.

I was experiencing a clunking sound from the rear axle during low RMP shifting or when the car lunged forward at low speeds. They re-torqued the rear axle nuts and that seemed to have taken care of the problem.

Neil Baker

If yours is a new Z51 it should have had an oil change at 500 miles.
There is a special procedure for checking Z51 oil level. After engine warm to hot, with engine off for 7 to 10 minutes, check level. Make sure the car is on level ground.

JerryU

Although I covered in my post #11, as usual that answer is too long for many who won't read past 140 characters!

The OP asked what is the level COLD? Simple answer, YOU CAN'T CHECK A DRY SUMP COLD!

For fun I checked "cold" after the car sat a day+ and it was ~5 quarts low! As soon as the engine is shut off, oil slowly drains back to the pan! MUST CHECK HOT BEFORE 10 MINUTES.