Buying used cars is a gamble and at a $3000-$5000 price point an even bigger gamble. Count on every car never having its oil changed in a manner/interval that preserves the engine. In fact plan on it consuming oil. If its a timing belt car it will never have had the timing COMPONENTS replaced even if it has 150k plus miles. Coolant will be the original coolant and we know heater cores and water pump replacement on modernish cars can be 10 hours labor. When my daughters got cars I seeked out financially set elderly people and middle class folks selling their cars. In the ad pics the condition of home and neighborhood- if in the pictures can say alot. With Face Book Market place you can see a pic of the seller. If he is wearing a backwards ballcap with a joint in his mouth flipping the middle finger its wise to pass on his car no matter how nice the car may appear.