A guide to choosing and caring for lubricants

The number before the “W” (for winter) shows how easily the oil flows when the engine is cold. The lower it is, the faster the oil reaches every part at start-up — the moment most engine wear happens. The number after the dash is the oil’s viscosity at 100 °C, the engine’s normal running temperature.

Mineral oils are refined directly from crude oil. Synthetic oils are made from highly refined or chemically built base oils with more uniform molecules, so they hold up better against heat, oxidation and cold. Semi-synthetic oils sit in between.

As a rule of thumb, most cars on synthetic oil can run around 10,000 km or one year between changes, and around 5,000 km on mineral oil. Short trips, heavy traffic, dust, CNG fuel and towing all count as severe use and call for shorter intervals.

Start with the viscosity range your pump maker recommends, then match the ISO grade to the operating temperature: ISO VG 32 for cold starts and precision systems, 46 for most machines, and 68 for hot climates and heavy presses.

The penetration grade shows how far a standard needle sinks into bitumen at 25 °C. Bitumen 60/70 is harder and resists rutting in hot climates and under heavy traffic; 85/100 is softer and resists cracking in cold regions.

Keep drums indoors or under cover, lying on their side with the bungs at the 3 and 9 o’clock positions so rainwater cannot collect on the lid. Use the oldest stock first.