Automotive Standards

Where possible we use Scientific Testing and measurement to determine if fluids and parts are within specification. In those cases where there is no Scientific Method we use industry-accepted methods as well as our own experience to make an intelligent decision and inform you about what is best for your vehicle.  By following these standards and methods, statistics show that we can save our customers as much as 50% in vehicle costs over the life of their vehicle by preventing costly repairs, eliminating unnecessary work and reducing the chances of breakdown and inconvenience. In order to better maintain our customer’s vehicles and deliver a consistent experience AC Auto Service Center has formalized standards for our technicians to use. These standards were developed by gathering information from Automobile Manufacturers and other Automotive Industry sources. 

We have also developed a standard vocabulary to describe vehicle problems and potential problems in order to be consistent and create better communication among our customers and staff. 


SEEP - means that you have wetness or dampness in an area but no dripping or fluid loss.  Seeps should be noted only and watched.

LEAK - a trail of liquid on a surface or in a tray that may not be dripping on the ground yet.  A leak should be recommended for repair before it becomes a drip and before a vehicle looses enough of its vital fluid to cause expensive damage.  Oils can leak and cause damage to other expensive components before progressing to a drip.

DRIP - liquid dripping on the ground. Should be repaired before major damage occurs.  (with the exception of water dripping from your a/c evaporator, which is natural and not a cause for concern). 

SEVERE LEAK - liquid dripping and creating a puddle.  Severe leaks should be repaired immediately as they can be dangerous to further vehicle operation.

          If you determine that the part or fluid is MARGINAL this means that a service or repair will be recommended based on condition but is not yet critical.  If you determine that the part or fluid is BAD this means that it has failed a scientific test or is outside of the manufactures limits for consistent operation and could cause unplanned for failure and additional expense.  If you determine that something is UNSAFE this means that it is outside of the manufactures safe operating specifications.  Unsafe means that it could fail causing major damage to the vehicle or endanger the life or the life of passengers in the vehicle. (We use the term unsafe very cautiously) And, of course, GOOD means that the part or fluid is within the manufacturer specifications and has no need of maintenance or repair at this time.


BRAKE PADS, SHOES AND TIRES are measured to accurately determine how much of their life is left.  Manufacturers of brakes and tires set a standard of 2/32nds (material remaining) as a baseline for replacement.  When your brake pads or tires have reached 2/32nds the manufacture states that they have reached their limit and should be replaced.

Due to the existence of several different levels of quality of new parts and the fact that some Brake Pads and Tires start their life at 8/32nds and some at 14/32nds it is necessary for us to make a few assumptions based on our experience.  We have set a standard based on the fact that 2/32nds equals 0% and 12/32nds equals 100%. This is in line with M.A.P Standards which are recognized by our industry. If your brake pads or tires are measured at 2/32nds or below we will recommend replacement.  If we state that your brakes are metal-to-metal or your tires have belt showing this means that your vehicle is unsafe and needs to be repaired now.  If you have 1/32nd or 2/32nds left we will tell you that we recommend replacement based on the fact that you have exceeded the manufacture limitations.  Based on the fact that some customers do not return for their scheduled maintenance on time and therefore may cause unnecessary damage to their vehicles we will recommend replacement if your brake pads or tires are at 3/32nds. However, we will let you know that you should make it to your next scheduled service and have the option to wait until then to perform these repairs.

COOLANT AND BRAKE FLUID has specific Scientific Tests and accepted Industry Standards to determine when these fluids need to be replaced.  Most German and Japanese manufacturer’s recommend that these fluids be routinely flushed every 3-years or 30,000-miles.

COOLANT - Industry standards tell us that most coolants need to be replaced when their pH level drops below 8 which is acidic. When coolant becomes acidic it starts to remove very small particles of metal from the hot engine block and distribute them in the coolest part of the cooling system, the radiator.  This causes a blockage of flow in the cooling system and can eventually lead to overheating and major engine damage.  If coolant is changed when it drops below a pH of 8 it can greatly reduce the chances of engine damage due to overheating, which is the leading cause of engine failure.

BRAKE FLUID also has very specific Scientific Tests to determine if it is good or bad.  The most accurate way to test brake fluid is with a Refractometer.  This tells us the moisture content of the fluid.  When a brake fluid reaches 2% moisture its boiling point drops below 320 degrees and has enough moisture in the brake system to cause damage due to Oxidization (rust).  It is also possible that on an extended braking period (such as coming down a mountain or steep hill) the moisture in the fluid could boil and cause partial or complete loss of braking.  As the moisture content increases the possibility of expensive repairs and loss of braking increases.  ABS brake systems should also be tested for copper content.  When the copper content exceeds set limits the chances of damage to expensive hydraulic components rises.  If you recommend that the brake fluid needs to be flushed this means that it has failed one or more of these Scientific Tests.

ENGINE OIL is a touchy subject and except for sending samples off to have them tested in a lab, which is not cost or time effective, the only acceptable standard comes from the vehicle manufacturer.  In the Winston salem area most vehicles need to have their oil and filter changed every (6)months or (5000miles.  Reading the owners manual proves this, “no matter what the Oil Industry wants you to think.”  Changing your engine oil and filter sooner is damaging to the environment and to your wallet.  We have found that changing our customers engine oil and filter every (6)months or (5000)miles is more than adequate which is proved out by the large number of our customers vehicles that have exceeded 200,000 miles and still run like new.  When a vehicle is only driven short distances on a regular basis it is even more important that the oil be maintained.  When you start your engine chemicals from the combustion process enter the oil and breakdown the oils ability to lubricate properly, for that reason we recommend (4months or (3500)miles whichever comes first.

TRANSMISSION FLUID like engine oil has no practical field test.  However, when the fluid changes color and smells burnt this is an indication that it has been overheated and can no longer completely perform the functions that it was designed for.  Transmission fluid is used to cool, lubricate and provide the hydraulic pressure necessary to make the transmission shift properly.  Once it has been overheated transmission fluid changes consistency and cannot perform any of these functions completely.  This will eventually lead to very expensive, and usually unplanned, transmission problems or failure.  You should suggest flushing or servicing the transmission when you determine that the fluid has been overheated.  You should also suggest servicing the transmission at the mileage that the manufacturer recommends.

POWER STEERING FLUID also has no practical field test.  Power steering fluid changes color and turns gray as the pump deposits minute metal particles into the fluid and the hoses start to break down internally.  This material acts like sand and damages other components within the system.  You should suggest flushing the power steering fluid whenever the fluid is gray to prevent damage and failure of other expensive components within the system.


DIFFERENTIAL AND TRANSFER CASE FLUID is changed based on the manufacturer recommendations.  This can vary greatly based on the type of fluid used by the manufacturer and the way the vehicle is used by the owner.  If you are using your vehicle for towing or excessive off-roading it is a good idea to change the fluids prior to what the manufacturer recommends.  If metal is found in the differential fluid this is a sign of damage and further investigation should be recommended.  Some metal in the transfer case is normal and you should use your experience to determine how much is too much and when further diagnosis is recommended.

COOLANT HOSES break down from the inside out and it is often impossible to predict an eminent failure.  However, if the coolant hoses are “crunchy”, “bloated”, leaking or, excessively hard or soft it is an indication of a potential problem and You should recommend that they be replaced before damage can be done to the customers engine.  Also, many manufacturers recommend that they be replaced at 6-years or 80,000 miles as a preventative measure.  If you can determine what the manufacturer recommends you should inform your manager so they can make recommendation about the customers  coolant hoses.

SERPENTINE BELTS have a very specific standard.  If there are more than 10 tiny cracks per inch then the belt needs to be replaced. They also need to be replaced when they have been soaked with fluids from another defective leaking component.  V-BELTS need to be replaced if they have any cracks or are excessively dry or liquid soaked.  Since these belts run the waterpump, power steering and air conditioning it makes sense to replace them whenever visual inspection indicates they need replacement to prevent expensive and unplanned failures on the road.