Buying a used car with over 100,000 miles: what to check on the engine and transmission

How to judge the engine and transmission on a high-mileage used car: the model year's complaint record, the paperwork to ask for, and your own checks.

By Eyal Malka · November 5, 2026 · Data: NHTSA, updated October 3, 2026 · How we score

A car with more than 100,000 miles on it is not a bad buy by definition. Plenty of engines and transmissions run far past that, and the price drop at six figures can be large. But the risk is different from a newer car's. On a 40,000-mile car you are mostly buying the model year's design. On a 130,000-mile car you are buying the design and everything the last owners did or did not do to it, and the bill for anything that goes wrong is entirely yours.

That means two questions, in this order. First: is this a model year whose engine or transmission owners complained about unusually often? Second: has this particular car been looked after well enough to get past that? This guide covers both, using NHTSA's public owner-complaint data for the first and plain checks for the second.

Start with the model year

The first filter costs nothing and takes a minute. Look up the model year's drivetrain share: the fraction of all NHTSA owner complaints about that year, make and model that concern the engine, the transmission or the fuel system. How to read these numbers.

On a high-mileage car this matters more, not less. A model year with a well-known engine or transmission pattern is one where a lot of cars have had the failure by now, and the ones that have not are still carrying the risk. A model year with a clean record is one where reaching high mileage is more likely to reflect the design than luck.

Most cars that have crossed 100,000 miles are older ones, so we looked at the older end of the data: model years 2010 to 2015 with at least 300 complaints on file, 274 of them. The median drivetrain share is 43%. Eighty-nine are under 33%, where we show no elevated signal, and 151 are at 40% or more. The figures come from tools/guide-stats.mjs.

The class makes a difference

Among those 2010 to 2015 model years, the median drivetrain share varies a lot by the kind of vehicle:

The pattern is broad, not absolute: there are clean compact cars and bad pickups in the same years. But a buyer shopping the small end of the market for an older car is shopping where the drivetrain records are weakest.

Older model years with the cleanest drivetrain records

The 2010 to 2015 model years with the lowest drivetrain share, among those with at least 300 complaints:

Older model years with the most concentrated drivetrain complaints

And the highest:

If the car in front of you is on this second list, the high mileage and the model-year pattern compound each other. That is not an automatic no, especially at a price that reflects it, but it is a car where you want proof that the known problem has already been dealt with, and an inspection by someone who knows what that problem looks like. The engine or transmission guide shows which of the two each problem model year is about, which tells you where to look.

The paperwork on a high-mileage car

At 100,000 miles the service history is worth more than any single check you can do on the day, because most of what kills a drivetrain happens slowly.

• Oil changes. Ask for receipts or a dealer service printout, not a sticker. Gaps of many thousands of miles beyond the interval in the owner's manual are a bad sign on any engine.
• Transmission fluid. Some owner's manuals list no transmission fluid change in the normal schedule, or list it only for severe use; check what this car's says. A car at this mileage that has had one, with a receipt, has had more care than most. A first fluid change on a high-mileage transmission is something to discuss with your mechanic before doing, not something to demand from the seller.
• Timing belt or chain. Check the owner's manual for the car's engine. If it has a timing belt with a replacement interval, and the car is past it, find out whether it was done. If not, price the job into your offer.
• Coolant and other scheduled services. The owner's manual lists them by mileage. A car that has had the 60,000 and 90,000-mile services done has a history you can check against.
• Major repairs. A replaced engine or transmission is not a red flag on a high-mileage car; it can be the best answer you can get, if there is paperwork saying what was installed and by whom. A replacement with no paperwork is a question mark.
• Recall and warranty work. A dealer of the brand may be able to tell you, from the VIN, what recall and warranty work has been done. Ask.

The FTC's advice to used-car buyers is that a vehicle history report is not a substitute for an independent inspection (FTC: Buying a Used Car From a Dealer). On a high-mileage car the history report is useful for title problems and accidents; it will not tell you how the engine was maintained. What a Carfax report does not tell you.

Checks you can do yourself

None of these replaces a mechanic, but each one can end the visit early and save you the inspection fee.

1. Arrive before the engine is warm. Put your hand on the hood. Many problems, from a slow-to-catch start to a rattle that fades as oil pressure builds, only show from cold. If the seller has already run it, ask to come back.
2. Check the oil. With the engine off and the car level, pull the dipstick. The level should be between the marks. Very low oil on a car being prepared for sale is a warning about consumption or leaks. Milky, frothy oil can mean coolant is getting into it, which is serious. The oil consumption guide covers the warning signs in more detail.
3. Check the coolant in the overflow tank, cold only. It should be at the mark and the right colour for the car, not rusty or oily.
4. Look underneath and around the engine with a torch for fresh oil or fluid. Old seepage on a high-mileage engine is common; wet, dripping fluid is not.
5. Start it and watch the exhaust for a minute. A puff of blue-grey smoke at start-up, or a steady blue haze when revved, suggests oil burning. White smoke that persists after warm-up and smells sweet suggests coolant.
6. Watch the dashboard as the car starts. Every warning light should come on briefly and then go out. A check-engine light that stays on, or one that does not light at all during the bulb check, is a reason to ask questions.
7. Read the fault codes. An inexpensive OBD-II reader plugged in under the dashboard shows stored and pending codes. A car with codes recently cleared will show its readiness monitors as incomplete, which is itself worth asking about.
8. Test-drive for the transmission. Cold, then warm; stop-and-go, then a hill, then a steady cruise. The full script is in how to check a used car's transmission.

Recalls on an older car

Run the VIN through NHTSA's free recall lookup at nhtsa.gov/recalls. On older cars there is a specific catch: NHTSA's lookup shows unrepaired recalls from the past 15 calendar years, unless the manufacturer offers more coverage. For the oldest model years on the used market that cut-off can start to matter. The lookup also does not show completed recalls or warranty extensions. How to check a VIN for open recalls explains how to read the result.

The inspection

At this mileage a pre-purchase inspection by an independent mechanic is not optional. The FTC recommends one even when a dealer says the car has been inspected (FTC). Give the mechanic something to work with:

• The model year's pattern: "owners of this year report engine trouble far more than usual" points them to the right things.
• What you saw: the oil level, any smoke, any codes, anything you felt on the drive.
• The paperwork: what has and has not been done, against the owner's manual schedule.

Ask specifically for a compression or leak-down test if the model year's complaints point to the engine, and a scan of transmission data and a road test if they point to the transmission.

Pricing it

If you are buying "as is" from a dealer, the FTC's Buyers Guide on the window says so, and it means the dealer will not pay for problems after the sale (FTC). On a high-mileage car, assume anything the inspection finds is yours to fix, and price it in. Anything due by the owner's manual schedule that has not been done (a timing belt, fluids, plugs) is a fair deduction. A model year with a known drivetrain pattern and no evidence the problem was addressed is a fair reason to walk away, however good the price looks.

Frequently asked questions

Is it a bad idea to buy a car with over 100,000 miles?

Not necessarily. The risk depends on the model year's record and on how the car was maintained. A model year with a clean drivetrain record and a full service history is a very different proposition from a model year with a known engine or transmission pattern and no records.

What should I check first on a high-mileage used car?

The model year's complaint pattern, by VIN, then the service records. Those two things tell you what is likely to go wrong and whether the car has been looked after. After that, check the oil and coolant cold, read fault codes, test-drive from a cold start, and get an independent inspection.

Which older used cars have the best engine and transmission records?

Among 2010 to 2015 model years with at least 300 NHTSA complaints, the lowest drivetrain shares include the 2010 and 2011 Chevrolet Tahoe, 2010 Toyota Prius, 2010 Mazda3, 2010 Toyota Corolla and 2012 Ford Edge. The full table is above.

Do recalls still get fixed on older cars?

NHTSA's recall lookup covers unrepaired recalls from the past 15 calendar years, unless the manufacturer offers more coverage. Check the VIN at nhtsa.gov/recalls and call a dealer of the brand about anything open.