Ask the Mechanic: What should I consider when buying a used car?

Hello Paul, I have saved up some money to buy a car but I cannot afford a new one. What should I check before buying a used car?


Hello Doreen, it might help to have a more technically inclined person at your side when buying a used car. You should consider five critical areas; engine condition, gearbox condition, signs of major accident record, legitimate ownership by the seller as well as unpaid parking tickets and police traffic fines.

Engine condition: Consider three critical areas; condition of the lubrication system to rule out burning of engine oil during combustion due to bad piston rings. Check the engine cooling system for overheating due to a damaged cylinder head or gasket or failure of the cooling fans or thermostat. Confirm that engine oil and coolant do not mix. Run the engine and check for blue or white smoke, which may suggest any of the above conditions. Car engine lubrication or cooling system repairs are expensive.

Check the gearbox carefully, especially if it is a conventional automatic or CVT type. Inspect the condition of the oil and if it smells burnt it may be aged or damaged. A road test will help to confirm this suspicion.

A walk around the car with an expert mechanic will help to reveal if there are signs of major accident repair. A car that has been through a major accident repair may not have integrity to protect you and all your passengers in the next unlikely event of a collision or roll over.

It is also important to confirm that the car you are buying is from a seller who holds the title of ownership and that there are no encumbrances or contestations to the title of logbook such as mortgages or part payments from previous owners.

A check with the Uganda revenue Authority registration department will help. It does not harm to check with local parking contractors and traffic police for unpaid tickets or outstanding fines.


The holy grail of used car purchases is a folder crammed with receipts for work carried out. This enables you to check the car’s history for the work carried out and parts fitted. Plus it allows you to check the mileage against what’s displayed on the dashboard. A service book is a valuable document too, as you can see who has serviced the car, and when it was serviced.


Hello Paul, what causes jerking of an automatic vehicle after engaging the gear lever at D (Drive)? Previously, this problem would occur when R (Reverse) was engaged. The mechanic had advised that I change the gearbox after which the problem was shifted from R to D position of the gear lever. One even suggested that there could be a problem with the vehicle computer. It is all guesswork. What is the solution?


Such defects and their causes vary quite starkly from make-to-make. However, the most likely problem is a blocked filter in the gearbox sump. The first solution is to drain the ATF (automatic transmission fluid) oil, remove the sump, clean the filter, and put fresh ATF. None of that will upset your bank manager.

If that does not solve the problem, the unlikely but possible problem would be the “clutches” (there are a dozen or more in automatic gearboxes) which are automatically engaged and disengaged by oil pressure. The hydraulic pipes to one or more clutches may be clogged. The longer a dysfunctional filter is allowed to continue, the more likely that problem will be. Remedy for that is a more elaborate gearbox overhaul.

Actually, “changing” the gearbox should be a last resort. If the replacement is brand new, it will be a very expensive way to remedy a possibly minor fault. If the replacement is old salvage, its condition is probably unknown. What has it been doing, why is it not still in the vehicle it came from? Unless the unit has been overhauled so thoroughly that the seller will give you a full written guarantee (not common practice here) you would be buying a discard and gambling good money on really bad odds.


Hello Paul, I would like to buy a manual car that uses diesel fuel but advice among Toyota brands. Please advise.


Hello Benjamin, it may not be easy to find manual diesel Toyota saloon cars on the Ugandan market. However, you will find a few Toyota pick-up trucks and station wagons with diesel engines and manual transmissions. Cars with manual transmission and diesel engines are reputed for exceptional fuel economy.

Manual transmission cars are more engaging and less bothersome when it comes to unexpected breakdowns, apart from the occasional clutch failure if you do not know how to use it properly. Your choice of a Toyota model should be influenced by the number of people you want to carry, amount of luggage and terrain where you will mostly travel. That will help you decide between an SUV or pick-up truck.


 Hello Paul, I am trying to decide between different cars, one uses horsepower and the other kilowatts. What is the difference? 


Hello Tony, horsepower and kilowatts are measurements of power. They do not stand for different type of cars or engines. Matter of fact, the two can be used interchangeably to describe an engine’s power. Engine power is usually measured in horsepower, a standard unit of measurement. Kilowatt is the measure of power in the SI metric system commonly used in Europe. For example, to convert from horsepower to kilowatt, one horsepower is the equivalent of 0.746 kilowatts or 746 watts.


Hello Paul, I need to choose between petrol and diesel cars. Both are Skoda Karoqs, similar specifications and prices. Which would you recommend?


Hello Denis, Go for the Petrol engine powered Skoda Karoq. The difference between the fuel consumption statistics for petrol and diesel Karoq engines are insignificant, especially if you are willing to drive the smaller 1.2 or 1.4 litre petrol engines which give better or similar statistics as the 1.6 or 2.0 litre diesel engines.

The service costs for a petrol engine are lower than those of a diesel engine. Petrol engines are easier to look after when they age. Diesel engines will most likely develop costly emission or intake system faults which will erode the benefits of stronger diesel torque. Besides, you are not buying a commercial pickup truck which requires diesel torque for hauling cargo.

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