Engine Oil Change: When, Why & How Often?

Engine oil does three jobs at once: it stops metal parts from grinding against each other, it carries heat away from the hottest parts of the engine, and it holds dirt and soot in suspension until the filter catches it. As oil ages it thins, collects sludge and loses the additives that protect the engine. Changing it on time is the single cheapest thing you can do for a long engine life.

How often should you change engine oil?

Always start with your owner's manual, because the interval depends on the engine and the oil it was designed for. As a practical guide for Indian driving conditions:

• Mineral oil: every 5,000 km or 6 months, whichever comes first.
• Semi-synthetic oil: every 7,500 km or 6–9 months.
• Fully synthetic oil: every 10,000–15,000 km or 12 months.
• Bikes and scooters: usually every 2,500–3,000 km, as small engines run hotter and at higher RPM.

If most of your driving is short city trips, stop-and-go traffic, dusty roads or towing loads, treat it as 'severe use' and change the oil sooner, closer to the lower end of the range.

Signs your oil needs changing

• The dipstick shows dark, gritty or sludgy oil instead of a clear amber colour.
• The oil level is near or below the minimum mark.
• The engine sounds louder or makes a ticking noise at start-up.
• The oil-pressure or service warning light comes on.
• You notice a burning smell or blue smoke from the exhaust.

Choosing the right grade

A grade like 5W-30 has two parts. The number before the W tells you how easily the oil flows when cold, so a lower number means faster protection at start-up. The second number is its thickness at running temperature. Use the grade and specification (API or ACEA) printed in your manual; a thicker oil is not automatically 'better'.

What a proper oil change includes

• Draining the old oil completely while the engine is warm.
• Replacing the oil filter and the drain-plug washer.
• Filling the correct quantity, then checking the level on the dipstick after a short run.
• Resetting the service indicator and noting the odometer reading.