5 Things You Need To Check Before Buying A High-Mileage Car

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Buying a new-to-you vehicle can be both exhilarating and terrifying. While searching for the perfect car and imagining all the ways you'll fix it up or personalize it to make it your own can be extremely fun, shopping for a vehicle is also stressful. That's especially true if you're in the market for an older car or a used vehicle with high mileage. High-mileage cars pose unique challenges, including an increased potential to have wear-related damage, which may not always be immediately apparent during a cursory inspection.

One mechanic-approved tip for buying a used car is performing a pre-purchase inspection. However, because of those distinct challenges and issues that shopping for a high-mileage car can present, it's extra important that you don't skip this step when looking for an older vehicle. That inspection should cover virtually every inch of the car, from the engine bay to the tailpipe and the interior to the wheels. Also, it's a good idea to bring a professional mechanic or a knowledgeable friend along with you, especially if you're an automotive novice. When it comes to performing that pre-purchase inspection, there are several things to which you should pay very close attention. This is specifically important if you're shopping for a high-mileage car, which may have more hidden wear-related damage than a newer vehicle.

If you're interested in learning more about how to inspect a high-mileage car before buying it, stick around. As a former professional auto repair technician who has performed innumerable pre-purchase vehicle inspections, I'll break it down for you. From the suspension and steering systems to the engine oil and more, here are five things you need to check before you buy a high-mileage vehicle.

Every modern vehicle needs various fluids to run properly. These automotive liquids include things like engine oil, coolant, brake fluid, power steering fluid, transmission fluid, and more. Not only are these liquids essential for your car to run smoothly, but they can also be great indicators of a vehicle's overall health. As such, checking them is an important step when inspecting a used car, especially one with high mileage.

When you check the fluids, some of the things you want to inspect closely include the liquid's condition, whether there are any foreign particles or debris in the fluid, and the level of fluid in the reservoirs. Checking the fluids' condition can translate to inspecting them for discoloration and analyzing the consistency. With the debris you want to look out for includes things like metal shavings, grime, flakes of rust and corrosion, and even small parts like bolts or washers. If the fluids look extremely old or are littered with debris, it could mean that the previous owner took very poor care of the car or that severe damage is already present. The fluids' levels also tie into this, as clean fluid at a healthy level is indicative of a well-cared for car, and a well-maintained vehicle is more likely to be a solid investment than one that was treated poorly.

It's important to note that not all cars have transmission fluid dipsticks, meaning that you may be unable to check the transmission fluid from the engine bay. If you want to check the fluid, which you should do as part of any pre-purchase inspection, you can perform this step from beneath the vehicle when you move on to checking the undercarriage and frame.

While you have the hood popped to check the fluids, it's also a wise idea to inspect a few other things in the engine bay. That includes checking parts like the serpentine belt, radiator hoses, various fluid lines, the engine air filter, and other components. You should also capitalize on the opportunity to inspect the bay for signs of fluid leaks or other damage. When it comes to cars with high mileage, it's not uncommon to find minor signs of wear and tear. However, you should keep an eye out for excessive and obvious damage.

As part of your inspection, you should check the serpentine belt's tightness and condition, keeping an eye out for fraying, glazing, or cracks. For the radiator hoses, use your fingers to squeeze them to check for dry rot, cracks, and weakness. Remember to scan the entire engine bay for signs of leaks, paying close attention to the valve cover gasket, engine block, and fluid lines. Some indicators of fluid leaks can include things like a grimy buildup and colorful, crusty corrosion.

Don't forget to open the air box and check the engine air filter, too. If the filter is extremely dirty or full of debris, it may be a sign that the car was poorly maintained. If you do notice any indicators of excessive wear and tear, like leaks or components that are damaged or in otherwise rough condition, you may want to reconsider your purchase or negotiate a lower price.

The next thing you need to check before buying a high-mileage car can involve getting a little dirty. However, it's vital that you don't skip this part of the inspection, so you may want to bring along an experienced mechanic if you're not comfortable doing it yourself. Checking the vehicle's frame and undercarriage involves looking for rust and corrosion along the frame rails, as well as the rest of the car's underside.

This is your opportunity to inspect the suspension and steering system closely, and it's also a great time to look for leaks below the vehicle, after you perform your engine bay inspection. While under the car, pay close attention to the areas most exposed to the road and the elements. This is especially critical if you live in a humid environment or somewhere that experiences harsh winters. Look for severe signs of rust and corrosion, like flaking metal or holes in the frame and undercarriage.

Check for rust and corrosion across every inch of the bottom-side of the car. Be sure to pay close attention to the suspension and steering systems, as well as things like CV axles, springs, the rack and pinion gear, fluid lines, and the fuel tank. Also, this is your opportunity to check the transmission fluid if your vehicle doesn't have an engine bay dipstick. Use the fill/inspection hole to check the fluid in sealed transmissions, and you can follow the same method to check the level of gear oil in the differential, too.

While you're on the ground inspecting a high-mileage car's frame and undercarriage, you should also check the vehicle's brakes and tires. Contrary to what you may believe, you can check a car's brakes without removing the wheel in most cases. For disc brakes, you simply need to peer through the spokes of the wheel and identify the brake pad's friction material between the brake rotor and the caliper. You should be able to see the pad touching the rotor. Eyeball the friction material's thickness, and if it's roughly 3 millimeters or thinner, the pads need to be replaced. 

To check drum brakes, you can remove the inspection plug on the backing plate (the backside of the drum brake assembly). Then, use a flashlight to check the friction material on the brake shoes. If they appear to be 3 millimeters or thinner, the brake shoes need to be replaced, too. Finally, check all visible brake hardware, like calipers, drum assemblies, and brake lines, for rust, leaks, and other damage.

When it comes to inspecting the tires, you should analyze the tread closely. Look for signs of uneven wear, like heavily worn tread on one side of the tire, as well as things like excessive cracking or visible wires. You can use a basic tire tread depth gauge, like the GODESON Tire Tread Depth Gauge, or you can use a U.S. penny. For this test, place the penny into the tread upside down. If you can see any part of Lincoln's head, the tires are due for replacement. While checking the tires, don't forget to pay attention to the wheels and keep an eye out for dents or cracks that could compromise the integrity.

After you've checked all of the points covered above, there's still one final step left in your pre-purchase inspection: the test drive. This step is vital when buying any vehicle, but it's especially critical when buying a high-mileage car. The test drive is the apex of your inspection process, and it's the part where you compare everything that you learned by physically inspecting the vehicle against what you learn by driving it.

During the test drive, there are a few points to which you should pay close attention. First, get a feel for how the vehicle accelerates and brakes. Ideally, you should be on a relatively straight road with little traffic. Then, test out the steering wheel and the car's handling by driving around some curves or swaying gently back and forth on an empty road. You should note any strange sensations in the steering wheel or brakes, like vibrations, shakiness, or grinding, and listen for any abnormal sounds coming from the suspension and engine bay. It's important that you drive at different speeds to test out the transmission and check for things like slipping gears or stiff gear changes.

If you're not comfortable or don't feel qualified to perform the test drive on your own, it's a good idea to hire a mechanic to come with you or bring a knowledgeable friend. The test drive is an extremely important part of any pre-purchase inspection, especially when the car has high mileage, so you need to make sure that you take it seriously and are equipped to notice any signs of damage or mechanical trouble.