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Second-rate parts mean second-rate results

When it comes to diagnosing a problem, one of the biggest mistakes is thinking that the problem is gone after you’ve installed a new part. I’ve had vehicles brought in countless times with the same old story attached to them. The customer will say:...

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GearWrench Launches Street Team, a New Mobile Driver Program

GearWrench, a premier hand tool brand from Apex Tool Group, has announced Street Team, a new program that gives independent mobile distributors the support of an established tool brand without the restrictions of a franchise. "Response to the program...

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AUTO 7 Named Approved Vendor For Automotive Parts Associates

Steven Kruss, president of Auto 7, which supplies Korean-made, OEM-quality automotive parts to distributors across North America, announced that Auto 7 has been named an approved vendor of Automotive Parts Associates (APA), one of the nation’s...

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Internal Engine Oil Consumption Diagnostics

Due to the variables in engine design and ­operating conditions, internal engine oil ­consumption complaints are often the most difficult to solve. In some cases, oil consumption might be more severe under low-speed operation, in other cases, high-speed...

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Hyundai Fuel System, Emissions Diagnostics

Hyundai has done a good job of improving its ­offerings over the years from both an aesthetic and mechanical viewpoint. Complemented by a strong warranty and good value, the carmaker has been able to increase its market share year over year. If you aren’t...

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Curing Volvo Manual Transmission Rattle

In an effort to increase fuel efficiency, today’s engines produce more torque so they can be ­driven at extremely low rpm. ­Reduced viscosity engine and gearbox oils, less vehicle weight and improved aerodynamics also contribute to better fuel economy....

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Talk To All Available Modules With Autel's MaxiDiag Elite MD802

Derived from Autel’s Professional Series tool, the MaxiDAS DS708, the MaxiDiag Elite MD802 enables the user to not only get into the OE enhanced OBD II system with mode 6 access and live data graphing, but it also allows a technician to scan the...

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Reflashing & Reprogramming Tools

In the first half of 2014, NHTSA has issued more than 15 recalls where the fix was to reflash a module on a vehicle. In the same time frame, more than 100 TSBs have also been issued where the solution is to reflash a module. These recalls and TSBs...

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Pulling Codes: An Advanced Misfire Story The Story of P0301

This article will document code P0301 — Misfire Activity on Cylinder No. 1 — a code many of you have run into, but sometimes we have case studies that are worthy of mention. Our subject vehicle is a 2007 Mercury Mountaineer. The vehicle has...

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The Why, Where, When of TPMS Sensors

To understand any TPMS relearn procedure, you have to understand this: Sensors only transmit, they do not receive. No vehicle asks a sensor for information on how it is doing. I know you’re thinking a sensor does receive signals when the vehicle...

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Most Common Causes of Misfire Codes

A flashing check engine light and a P0301 to P0312 diagnostic trouble code (DTC) is a surefire indication that one or more cylinders are misfiring. Occasional misfires may pass unnoticed, but a steady misfire is hard to miss. The engine usually feels...

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Pattern Failures of MAF and MAP Sensors

Pattern failures are those failures that happen over and over again — and the same applies to how customers describe these failures. Customers might unknowingly give you the answer to their problem without needing to open the hood. In this article,...

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Home Brakes Brake Fluid Q & A

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Mike Evangelo of Dynamic Motorsports and Rossion Automotive e-mailed me with six questions about brake fluid. I like a challenge, so here are my answers.

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 different.

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 if an older rubber part that has a high concentration of natural rubber, they 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, this is why it is safe for breast implants. 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, chance are greater that corrosion is 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. Some have said that they have noted a better pedal feel with synthetic fluids. Is this possible?
Some very high-end synthetic DOT 4 and 5.1 synthetic fluids can give a better 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.

Thanks Mike!

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Andrew Markel

Andrew Markel is an ASE Certified Technician and former service writer, and he brings this practical knowledge to the Brake & Front End team as editor.
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