Ask the Mechanic

Thursday February 11 2021
By Paul Kaganzi


Hello Paul, which engine oil do you recommend for a 22-year-old petrol engine? I used to use a multi-grade mineral oil but I changed to mono grade. Due to a suspected reduction in the oil level, the sound of the engine changed and also got early morning issues of slow start and strange sounds. Please advise. Patrick

Hello Patrick, your problem is not the choice of engine oil between mono grade and multi-grade. Your engine is leaking oil internally. You need to get a compression test from a garage with a compression tester.

An engine will leak oil into the combustion chamber due to bad piston rings. This causes a continuous drop in the oil level, excessive blue smoke, delayed ignition and poor performance due to low oil compression and oil infiltration of the spark plugs and fuel air mixture.

The noise when you start the engine suggests damage due to delayed lubrication of the upper engine. Causes of delayed lubrication include sludge clogged oil pickup strainer and galleries, bad oil pump or low oil levels due to internal oil leak. This will cause damage of fast-moving metallic components in the upper engine when they run without oil lubrication and cooling.

Ordinarily, a 22-year-old engine will run well on a manufacture-recommended multi-grade mineral oil or fully synthetic oil. These oils should be blended with excellent protective and performance enhancing attributes suitable for our climate and the recommended service interval. When an engine ages or is not looked after well, it will develop internal leaks.


Use of mono grade oil which is blended with additives that slow leakage in older engines can provide some relief. However, an engine with a difficult cold start or noisy cold runs may require more than mono grade oil. A compression test and inspection will determine the extent of damage and inform the choice of interventions.



Hello Paul,

I need your advice on my Land Cruiser TX squeaking/whistling brakes. My usual service provider thought it was the quality of the pads and did not think there was a problem with the discs. The squeaking is as bad as before. Can you help? Hassan.

Hello Hassan, it is true the quality of brake pads can sometimes be the cause of squeaking and ‘whistling’, especially if they are made of a blend of metallic materials. The best quality of brake pads will be made of ceramic. Often, worn out pads will alert you when the break wear warning plate touches the disc and starts to squeak.

The other common cause of squeaking are extremely worn out brake discs. These discs develop grooves as a result of delay to replace the worn out brake pads. If the disc width is below safe limit, replace them. If the disc width is within safe limits, they can be slightly skimmed on a lathe machine to remove the grooves. Use a professional brake disc and pad width measuring tool.



Dear Paul, my Toyota Passo is consuming a lot of fuel yet it is a 900cc. A full tank lasts only 10 days. I have had a mechanic check the spark plugs but he says all is well. What could be the cause?


Hello Pedson, a Passo engine with less than one litre cubic capacity should be a super fuel saver. The Passo tank capacity is 40 litres. If it takes you 10 days to empty the full tank, it would be good to find out how many kilometres you cover during that time. You can reset your trip metre after filling the tank with 40 litres and observe mileage covered when the fuel empty light comes on.

On average, a 900cc Passo should give you a fuel economy of about 21km/ litre of petrol. With sensible driving, efficient fuel and a well-tuned engine, you can ‘squeeze’ more kilometres out of a litre (push the fuel economy envelope).

Should your fuel economy be below normal, have computer diagnostics check that the car emission system is fine. Occasionally, bad oxygen sensors will cause a spike in fuel consumption when the engine management system delivers unregulated amounts of fuel.

That condition also causes a check engine light. A dirty air filter and bad tyres can also contribute to poor fuel economy.

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