QN: I own a four-year-old car. Can I mix a new coolant with the existing coolant in the radiator?

Today's long-life coolants work as advertised as long as two conditions are met.

First, they must be used as instructed and must not be mixed. Second, the radiator system must be maintained properly and topped up with clean water.

You should fill up with only the new coolant, after draining the radiator.

Be sure to select a coolant that meets all the the manufacturer's specifications. You can refer to the car owner's handbook for that.

I sense that my car's steering is 'wandering', especially at moderate speeds. Could it be due to worn-out steering ball joints?

Yes, it is possible. Steering ball joints are one of several components critical to the car's steering system. Problems with any of these components can cause damage and wear to other parts.

If one or more ball joints have worn out and need replacement, you might notice a loose or 'wandering' steering feel, especially at moderate speeds.

Another symptom of worn-out ball joints is unevenly worn tyres.

The best way to identify the cause of any steering problem or uneven tyre wear is to have the car aligned by a reputable workshop using well-maintained alignment equipment.

The process should identify any parts that are misaligned, loose or worn. If you have either abnormal tyre wear or a loose steering condition, get the car aligned and be sure to replace all worn parts promptly for safety's sake.

Automobile Association of Singapore