• 
• 

Published on November 21, 2007

Dear Khun Kingsley,

My name is Audi, and I am a subscriber to The Nation and Krungthep Thurakij newspapers. I'd like to congratulate The Nation on its newly launched Auto section. I have more than one car, so some get driven on weekends for only a few kilometres (10-20km). I have a question about engine-oil changes. I now use mostly the fully synthetic type (Castrol SLX).

Regards, Audi.

When considering engine oil, we must first understand that whenever the container is opened, air will make contact with the oil, and there is a chance moisture will get in, even if only a little.

In used engine oil, even if the car is used infrequently, there is also a chance water drops will form. So even if the engine is used over only short distances, the oil containing the water droplets should be removed.

It is known that water is heavier than oil, so if there is water in your engine oil, it will sink to the bottom of the oil sump after the engine is stopped and the car is left standing for a while. To drain the water, just unscrew the sump plug and allow about half-a-litre of oil to flow out. Then replace and tighten the plug and top up the engine oil to the level recommended by the car's manufacturer.

It does not matter whether the new oil you add is of the same brand and formula as the existing engine oil.

Used oil should be drained from the engine and replaced with fresh oil about every six months. If it has been a year and the mileage travelled by the car has not yet reached that recommended for your next oil change, then I suggest you change the oil and replace the oil filter, as well.

For vehicles that are not used often, and even then for only 10-20km, always check the parts related to engine cooling, especially the radiator and thermostat. If the vehicle is not driven far enough for the engine temperature to open the thermostat valve, rust in the water may collect in the thermostat area, causing it to malfunction or not to open fully when it is needed. This can lead to overheating.

I always advise people who drive their cars over only short distances to adopt the following practices. Using vehicles only once a week does not cause any damage to the engine, but it should be driven for at least 30 minutes each time. Check the water-temperature gauge and make sure the engine reaches normal operating temperature. Also, rev up the engine above the normal speed or reach at least 80kph for 3-4km. At this speed, the engine will be running fast enough to activate the water pump and get the coolant moving.

Another good reason for doing this is to let the catalytic converter collect enough heat to burn and clean up the exhaust gases. It also cleans up the catalytic converter as well.

Don't forget: vehicles that are driven only a little bit have as much chance, or even more, of being damaged as those driven every day. So if you have many vehicles, try scheduling a drive for each of them.

Pattanadesh Asasappakij

The Nation

E-mail your motoring questions to Pattanadesh@nationgroup.com.

 

 

Ultimate in Luxury

The Luxury LS 460 is a wonderfully comfaortable car fitted with all mod cons, althoough not necessarily the most fun vehicle to drive.