Can You Answer All of These Questions an Auto Mechanic Should Know?

Any mechanic can identify internal transmission issues from the fluid alone. Black fluid indicates worn-out internal clutches. Sticky fluid indicates overheating. Smelly fluid indicates high heat that caused the fluid to burn.

An overinflated tire tends to bulge in the center of the tread. This puts most of the car's weight on this center section and causes it to wear out prematurely.

You should always tighten lug nuts in a crisscrossing pattern. This ensures you tighten the wheel evenly and avoid stretching or weakening the wheel studs.

A Road Force balancer is a special machine that applies force to the tread of the tire for more effective balancing. It can also detect flaws in a rim and tire, and recommend match-mounting the tire and wheel to offset these imperfections.

Turning a rotor means to put it on a lathe and shave off small amounts of material to remove any imperfections. This helps prevent vibration and decreases stopping distances by giving the brake pads a rough surface to grip. Every brake job should include turning or replacing the rotors.

A parasitic draw is a small electrical issue that pulls a small amount of power from your battery when the vehicle is off. Under normal operation, you likely won't notice an issue, but if it sits overnight or for a few days, it could kill the battery.

GM began using Dex-Cool -- a silicate-free, orange-colored coolant -- in the 1990s. While this coolant was supposed to be a longer-lasting alternative to the green stuff, there have been numerous complaints and lawsuits surrounding corrosion and co0ling-system clogs causing major damage.

When a transmission starts slipping, this means there is already internal damage. Forcing new fluid into the transmission can actually cause more damage or even lead to complete transmission failure.

The transmission fluid not only lubricates the transmission's moving parts, but it also acts as the hydraulic fluid and washes away any loose debris. Failure of any one of these functions can result in serious transmission damage.

The D.O.T number shows the factory and batch numbers, and the manufacture date of your tires. This way you know how old they are and the manufacturer can easily issue recalls for select batches of tires.

A directional tire's tread is designed to only roll one direction. These are typically high-performance tires with asymmetrical tread patterns. These tires will have an arrow pointing in the direction they are supposed to roll.

They are organic, semi-metallic and ceramic. Organic pads are typically cheapest, and are a mixture of natural materials, like glass, rubber and more. Semi-metallic pads mix in metallic fibers for longer life and better stopping power. Ceramic pads replace the metal fibers with ceramic ones to reduce brake dust.

The oils on your fingers can transfer to the light bulbs on installation. These oils can get very hot and cause the bulb to burn out prematurely. Wearing gloves can prevent this transfer of oil.

Rusty bolts are the bane of a mechanic's existence, but they are not impossible to work with. Most shops keep a torch handy to heat up these bolts and break down the seemingly impossible bond the rust has created. After heating the bolt, it should come out under normal pressure.

Almost every vehicle has quick toe adjustment, but camber and caster may require special bolts or shims to get right. Most parts stores stock these items. In some cases, the only way to fix severe issues is with new parts.

Most rear calipers use a screw-style piston to activate the parking brake. This piston requires a delicate combination of clockwise rotation and inward pressure to compress it. The only way to effectively do this is with a special rear-caliper tool. Many auto parts stores rent these tools to DIYers.

Most major roadways have a peak in the middle and mild slopes downward on the edges. This can cause a car to drift slowly to the right. It is still a great idea to check his alignment, but make sure to set this expectation of the mild drift.

While an alignment can technically cause a vibration in some instances, these are very rare occurrences. Vibrations typically stem from tire or braking issues. It's always worthwhile to check the alignment, but you will also want to check the tires and brakes.

In its midsize sedans from the mid-1990s through the early-2000s, Chrysler saved room under the hood by putting the battery in the wheel well. To access the battery, you had to turn the wheel to one side and peel back the wheel-well cover.

Each model's brake system is different, so their brake hoses route in different ways. This means each model of vehicle will have a different brake-bleeding procedure. You must do this in the right sequence or risk reintroducing air into the brake system.

An "EVAP" code means there is a vacuum leak in the evaporative emissions system, and the fuel tank is part of this system. Oftentimes, drivers will refill their fuel tank and forget to tighten the cap, which may trigger a check engine light with an "EVAP" diagnostic code. This does not mean this code always points toward a fuel cap, but it is the best place to start.

Blown fuses and relay sometimes cause the most frustration for any tech chasing down what appears to be a mystery electrical issue. Starting at the fuse and relay block can eliminate the frustration of finding out you spent three hours chasing an issue that ended up being just a blown fuse or faulty relay.

If the thermostat fails and does not let the coolant flow back into the radiator, the engine will overheat but the upper radiator hose will remain dramatically cooler than the lower hose because no coolant will flow through it.

A free diagnostic is purely to give you an idea of where to start, and a "Random Misfire" code can lead you down several paths. The safest bet is to get a per-hour diagnostic approval so you can find the source of the problem and fix it the right way.

Many performance cars, especially German ones, have their suspensions tuned for carrying passengers and still delivering top-notch performance. This means an alignment technician must simulate the weight of the passengers and driver in the car. They do this using special sand bags.

The timing belt is one of the most sensitive and expensive belts in your vehicle. While replacing it, it is best practice to also replace all the timing belt pulleys, tensioners and the water pump. This helps prevent other problems in the area from damaging the expensive repair you just did.

Every manufacturer's hubs are different diameters, and installing wheels directly onto these hubs can cause vibrations. Hub centric rings sit inside the hub of the aftermarket wheels and fit snugly over the manufacturer's hub, preventing vibrations.

Plugs are great for quick on-the-road repairs, but they are not a permanent solution. The only permanent repair for a punctured tire is an internal patch bonded to the tire itself.

A/C systems should never leak refrigerant, as they are sealed systems. If the refrigerant level is low, there is a leak somewhere and refilling a leaking A/C system is actually a violation of federal law.

Torque sticks attach to an impact gun like any other socket. The socket is at the end of a long, thin stem that varies in size to help limit the amount of torque transfer from the gun to the lug nut. This allows mechanics to quickly reinstall wheels without worrying about overtightening them.

Underinflated tires tend to sag in the center, putting all the weight on the outer edges of the tires. This causes excessive wear on the outer edges of the tread.

Timing belts in interference engines -- those with very tight tolerances -- can cause valve damage if they break during operation. That said, a broken timing belt is not a death sentence. A full inspection may prove there was no valve damage.

While people are quick to say, "My rotors are warped," they fail to realize just how hard it is to actually warp them. Typically, vibration when braking is from brake pad material transferring from the pad to the rotor due to high heat. A quick rotor resurfacing generally fixes the issue.

Non-serviceable rotors are ones you cannot resurface on a brake lathe. Whether it's because the rotors are manufactured within tighter tolerances or just made of a metal that cannot be resurfaced, you have to replace them every time you replace the pads. You'll typically find these on performance and foreign cars.