Torque Shop: High engine consumption

The most common cause of high oil consumption is worn piston rings.
The most common cause of high oil consumption is worn piston rings.PHOTO: ST FILE

What causes high engine oil consumption? This is a problem I have recently encountered. I was advised by one workshop mechanic to use an additive which he claimed would reduce oil consumption. Is there such a thing?

The most common cause of high oil consumption is worn piston rings. Made from special alloys, these rings go around the circumference of a piston and serve as the seal between the combustion chamber and crankcase of the engine.

They are made for a very tight fit, even if the rings are designed to accommodate thermal expansion. Because of this, the rings are able to prevent engine oil along the cylinder walls from seeping into the combustion chamber.

Over several thousands of kilometres, the pistons and cylinder walls will experience wear, compromising the seal. This is when oil seepage begins to occur.

There will be a noticeable increase in oil consumption and eventually, bluish-grey smoke spewing out the exhaust pipe.

Regular servicing with high quality engine lubricant will prolong the life of piston rings and delay the onset of cylinder wall wear.

But over time, wear will still set in. Continuing to run a car with worn rings will cause a deterioration in overall performance and contamination of the oil, which further exacerbates wear - not just to the cylinders but also other parts such as the crankshaft bearings.

Hence, replacing the rings is the only remedy.

Additives are nothing more than temporary relief and some may even cause further engine damage in the long run.