Torque Shop

At a recent refuelling stop, the attendant cleaned the windscreen and offered to check the engine-oil level of my seven-year-old Honda. Apparently, the oil level was low and he recommended the oil and quantity to replenish. After I bought the oil, he helped me top it up. It has been four days now and I have noticed that my car is emitting a lot of exhaust smoke and there is a strong burning smell. What has happened and what should I do?

First, checking the dipstick to determine oil level must be done only when the engine has been switched off for half an hour or longer.

When the engine is running, most of the oil in the sump is pumped through the various lubrication channels. The sump, which is at the bottom of the engine, acts as a reservoir to collect the oil for the pump to continue circulating.

Once the engine is shut down, the oil will drain into the sump. Unlike water, hot oil takes time to flow down and settle into the sump. This could take 30 minutes or longer. Only then will the dipstick indicate the actual oil level in the engine.

People's visits to petrol stations are typically brief. There is definitely not enough time for all the oil to return to the sump. Hence, the dipstick may give a false low reading.

Over-filling of oil will lead to problems. Excess oil might enter the cylinders, resulting in a smoky exhaust, as well as a burning smell as oil is combusted.

If the vent valve gets overwhelmed, oil fumes may build up in the crankcase, which would strip vital surfaces of lubricant.

You should get to a workshop as soon as possible and ask a mechanic to drain the excess oil.

Shreejit Changaroth

A version of this article appeared in the print edition of The Straits Times on October 31, 2020, with the headline 'Torque Shop'. Print Edition | Subscribe