When mileage doesn't tell the full picture
Posted: 05 Oct 2010, 10:56 pm
This post serves to dispel the myth that low mileage cars are 'good' and high mileage cars are 'bad'
When looking at a car, many people have a natural preference to gravitate toward cars with lower mileage, but here are reasons why mileage is not always a good indicator of the health of the engine:
1. Mileage does not tell the story of how the car was maintained
Let's say that Car A has 100,000 km on the odometer. However, owner is able to provide full history, showing that oil was changed every 5,000 km, and gear oil, differential oil, transfer case oil, and brake fluid is changed every 10,000 km, and oil cooler and radiator is flushed every 10,000 km. Engine oil used is of the correct viscosity and grade
Car B only has 50,000 km, but has only had two oil changes done using a generic engine oil that is of the wrong grade and viscosity.
Which car would you buy?
2. Mileage does not tell the story of how the car was driven
Owner of Car A has driven stick for over 10 years, shifts before the red line, but uses a broad rpm range from 0 to 6000 rpm. Car A has 100,000 km on the odometer
Owner of Car B does not know how to drive stick. It's his first manual performance car, and he shifts when the needle bounces off the rev limiter for 10 seconds or so in every gear because it's cool to hear the 'bang-bang' backfiring sounds. He crunches gears and rides the clutch.
Which car would you buy?
3. Mileage does not tell the story of how the car was used
Car A spends 80,000 km of its 100,000 km history on the highway.
Car B spends 25,000 km of its 30,000 km history on hillclimbs, or in rallies.
Highway miles are far kinder on an engine than city miles (i.e. stop and go traffic).
Which car would you buy?
4. Mileage does not tell the story of how the car was owned
Car A is driven every day, 365 days a year. Runs 100% coolant. Engine block (e.g. 4G63 or VAG 1.8T) is made of cast iron.
Car B is driven once every 2 weeks. Runs a mix of coolant and distilled water. Same engine block.
Condensation happens inside the block. Water and cast iron. Rust inside the block? Check the coolant outlet lines for signs of rust. Once rust starts to form inside the block, it never goes away. Like a cancer, it can be slowed down, but it is always there. This is one reason why a car needs to be started at least once a week, or every 2 to 3 days if possible even if it is not driven, and especially with cast iron engine blocks.
If DOT5 brake fluid is used in the car, water will also settle inside the brake system and cause the calipers and pistons to rust, increasing the risk of a jammed piston.
So, how do you know if a car is 'good'? There are no guarantees, only risk management. Understand that buying a performance car is almost always a gamble. Whether you spend you next AED10,000 and 2 weeks fixing up the car, and 10 days a month to get things fixed in the coming months is something you can control if you keep the above in mind.
Sit down and spend some time with the owner of the car, watch him drive, and see how much he understands about the maintaining the car. If the car is modified, either you know more (based on research or experience, but never hearsay) than the owner, or you know less. If the owner is knowledgeable, chances are, you're pretty safe.
How has the car been modified? Does it have 500 bhp, running on stock internals, stock intercooler, stock injectors, stock oil cooler, and used on track? Modifying a car for performance isn't something that's done by hearsay. It's done with knowledge and experience. The more you have, the lower the risk you face. The more the owner of the car that you're buying has, the lower your risk.
Information and understanding gained through research is knowledge.
Information gained through hearsay without understanding is never a good idea.
** All credits to the original poster who wrote this up ** taken from another forum
When looking at a car, many people have a natural preference to gravitate toward cars with lower mileage, but here are reasons why mileage is not always a good indicator of the health of the engine:
1. Mileage does not tell the story of how the car was maintained
Let's say that Car A has 100,000 km on the odometer. However, owner is able to provide full history, showing that oil was changed every 5,000 km, and gear oil, differential oil, transfer case oil, and brake fluid is changed every 10,000 km, and oil cooler and radiator is flushed every 10,000 km. Engine oil used is of the correct viscosity and grade
Car B only has 50,000 km, but has only had two oil changes done using a generic engine oil that is of the wrong grade and viscosity.
Which car would you buy?
2. Mileage does not tell the story of how the car was driven
Owner of Car A has driven stick for over 10 years, shifts before the red line, but uses a broad rpm range from 0 to 6000 rpm. Car A has 100,000 km on the odometer
Owner of Car B does not know how to drive stick. It's his first manual performance car, and he shifts when the needle bounces off the rev limiter for 10 seconds or so in every gear because it's cool to hear the 'bang-bang' backfiring sounds. He crunches gears and rides the clutch.
Which car would you buy?
3. Mileage does not tell the story of how the car was used
Car A spends 80,000 km of its 100,000 km history on the highway.
Car B spends 25,000 km of its 30,000 km history on hillclimbs, or in rallies.
Highway miles are far kinder on an engine than city miles (i.e. stop and go traffic).
Which car would you buy?
4. Mileage does not tell the story of how the car was owned
Car A is driven every day, 365 days a year. Runs 100% coolant. Engine block (e.g. 4G63 or VAG 1.8T) is made of cast iron.
Car B is driven once every 2 weeks. Runs a mix of coolant and distilled water. Same engine block.
Condensation happens inside the block. Water and cast iron. Rust inside the block? Check the coolant outlet lines for signs of rust. Once rust starts to form inside the block, it never goes away. Like a cancer, it can be slowed down, but it is always there. This is one reason why a car needs to be started at least once a week, or every 2 to 3 days if possible even if it is not driven, and especially with cast iron engine blocks.
If DOT5 brake fluid is used in the car, water will also settle inside the brake system and cause the calipers and pistons to rust, increasing the risk of a jammed piston.
So, how do you know if a car is 'good'? There are no guarantees, only risk management. Understand that buying a performance car is almost always a gamble. Whether you spend you next AED10,000 and 2 weeks fixing up the car, and 10 days a month to get things fixed in the coming months is something you can control if you keep the above in mind.
Sit down and spend some time with the owner of the car, watch him drive, and see how much he understands about the maintaining the car. If the car is modified, either you know more (based on research or experience, but never hearsay) than the owner, or you know less. If the owner is knowledgeable, chances are, you're pretty safe.
How has the car been modified? Does it have 500 bhp, running on stock internals, stock intercooler, stock injectors, stock oil cooler, and used on track? Modifying a car for performance isn't something that's done by hearsay. It's done with knowledge and experience. The more you have, the lower the risk you face. The more the owner of the car that you're buying has, the lower your risk.
Information and understanding gained through research is knowledge.
Information gained through hearsay without understanding is never a good idea.
** All credits to the original poster who wrote this up ** taken from another forum
