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Do Training, Technology And Parts Sourcing Issues Keep You Up At Night?

We often hear that the things that keep shop owners awake at night pertain to profitability, productivity, training, keeping up with technology, shop operations/expenses and parts quality/availability. This month, we hear directly from one of your...

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Top 10 Automotive Repair Shop Pet Peeves

No two days are the same for the owner of a repair shop. Every day brings its unique set of challenges to overcome, but, for the most part, the day progresses along and one day passes to the next. But, there are those occasions when certain daily activities...

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Keeping Counterfeit Parts Off The Road

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Engine Coolant Temperature Diagnostics

While old-school cooling system service often ­focused on coolant leaks and overheating engines, let’s begin thinking “new-school” by looking at modern cooling systems through the eyes of the engine coolant temperature (ECT) sensor. Coolant temperature...

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Volkswagen: Parking Indicator Sounds Off with No Obstacle

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Volkswagen: Unnecessary Electric Coolant Fan Replacements

Model: 2006 Volkswagen Jetta Sedan Customer concerns of “electric coolant fans continue to run after the ignition is switched off” are resulting in unnecessary coolant fan replacements. It is considered normal operation for the electric coolant...

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Educating Drivers, Technicians and Service Advisers with Dill’s New TPMS Videos

Dill Air Controls has launched its new TPMS training and educational videos, supporting three audiences — consumers, technicians and service advisers. The consumer videos are available in shortened versions, and are positioned for the customer waiting...

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Top 5 Tools: Kenny Younkins, Ken’s Auto Service Center

Kenny Younkins, owner Ken’s Auto Service Center Akron, OH While Ken first said his favorite tool is his fishing rod, he said in the shop he prefers these five:   Snap-on 3/8” Drive Impact Wrench Mastercool Brake Flaring Kit Mitchell...

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Mitchell 1 Enhances Quick Links and Printing Functions in Latest Release of ProDemand

Mitchell 1 announces it has made several important enhancements in the latest release of its ProDemand repair, diagnostic and maintenance information program as a direct response to customer feedback. The implemented changes include an expanded Quick...

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Ford: Smoke From Vehicle When Starting

Vehicle: 2005 Ford Taurus SE, 3.0L Complaint: The customer says smoke comes from vehicle when starting. Cause: Confirmed the customer’s complaint and found smoke coming from the vehicle when the engine was started. Inspected the vehicle and found...

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R-1234yf Safety Procedure Checklist

Remember that R-1234yf is only mildly flammable. To become flammable, the mixture of air and refrigerant in a closed area like a vehicle cabin would need to be between 6.5% and 12.3% of the chemical vapor. This mixture must then experience a significant...

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Refrigerant Revolution: What R-1234yf Means for Service, Equipment, Safety

The new R-1234yf refrigerant is more than just a new jumble of numbers and letters on a label. For your shop, R-1234yf means several new procedures, a certification and new equipment in order to properly handle these new systems. Why the difference...

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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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