Car Repair Check
Car Repair Check

It is always exciting when purchasing a car whether the car is new or used. When purchasing a used car, it is important to take extra measures to make sure you are getting a dependable vehicle that will not fail on the road.

Engine oil and transmission fluid are what helps lubricate components in the engine and transmission. Without proper oil or fluid levels, it can lead to expensive repairs. Here are some of the steps to take to check for leaks when inspecting a used vehicle.

How to Find Oil Leaks on a Used Car

First, get yourself a good flashlight, floor jack, jack stand, shop rag, and mechanic or latex gloves. When inspecting an engine or transmission for possible leaks, always conduct a visual inspection. It will give you the impression of whether the vehicle has been taken care properly.

Start by opening the hood. Use a flashlight and shine on the engine. If the engine cover is on the way, remove it for better visual. Remove the engine dipstick and check the oil level and oil color. The oil level should be on the full level. If the engine oil is on low or below the low level, it is possible that there may be a leak.

  • Engine Area: This is the most common place to find oil leaks. Check around the oil pan, valve covers, and the oil filter.
  • Transmission: Look for leaks around the transmission pan, seals, and gaskets.
  • Differential: Especially in rear-wheel-drive cars, check the front and rear differential for leaks.
  • Power Steering System: Inspect the power steering pump, hoses, and reservoir for any signs of leakage.
  • Turbocharger: If your car is turbocharged, check around the turbo unit and its oil lines.
  • Oil Cooler: Some cars have an oil cooler. Look for leaks around its connections and seals.
  • Oil Filler Cap: Ensure it’s tight and not damaged, as a loose or damaged cap can cause minor leaks.
  • Oil Drain Plug: Located at the bottom of the oil pan, ensure it’s tight and the washer isn’t worn out.
  • Crankshaft Seal: Check both the front and rear crankshaft seals for any signs of leakage.
  • Camshaft Seals: These can also be a source of oil leaks if they become worn or damaged.

Top of Engine Leaks

Check the valve cover area, which is located on top of the engine. There should be no leaks, or dirt accumulated on the valve cover seal. If there is, that is a sign that it has been leaking. Usually, when the valve cover has been leaking, engine oil leaks from the top of the engine to the bottom.

The good news is that it is not expensive to repair. If you are handy and mechanical inclined, you may be able to replace the valve cover gasket yourself.

Bottom of Engine Leaks

Next, check the bottom of the engine. There are a few areas you will want to check. Ask the seller permission if you can lift the vehicle and place it on a jack stand. Check the engine oil pan gasket for possible leaks. If there is a leak present, the gasket will be full of dirt and oil. In addition, check the engine drain plug for possible leaks. Sometimes, when a drain plug is removed after many oil changes, the threads start to wear.

This will allow engine oil to seep through. Next, check between the engine and transmission for a possible leaky rear main seal. Usually when a rear main seal is severely, it will leak very fast.

Other Areas to Inspect

Next, check the crankshaft pulley for possible leaks. Behind the crankshaft pulley is the front main seal or crankshaft seal. This area can also leak due to high mileage and wear and tear. Next, if the vehicle is timing chain driven, check around the timing chain cover; It is possible it can leak due to high mileage or simply worn seals. Furthermore, if the vehicle is timing belt driven; you will want to check below the timing cover for possible leaks.

Two things will cause a leak. One is a bad camshaft seal and secondly a bad crankshaft seal. In addition, check around the oil pressure sensor for leaks and engine that is equipped with solenoids.

Transmission Leaks

Now that the engine has been inspected for possible oil leaks, it is time to check the transmission. Check the transmission pan for possible leaks with a visual inspection. Dirt will accumulate around the transmission gasket if there is a leak.

Inspect around the shift solenoid and transmission drain plug for possible leaks and lastly check around the axle seals. Transmission fluid can leak in that area if the axle seals are worn.


It is almost impossible to be 100% certain that a used car you are looking at does not have any oil leaks. Also, some car auctions may not even allow you to inspect the cars for sale. However, most will and it is very important to take advantage of the opportunity.

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Last updated on August 19th, 2023 at 11:20 am

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