Low viscosity engine oils

Many later vehicles use low viscosity engine oils to reduce fuel use, lower emissions and improve engine responsiveness. Its common to find oils such as 0W 30, 5W 30 and 10W 40 specified for even run-of-the-mill later model vehicles.

However producing oils of low viscosity that provide the necessary engine protection and minimal oil consumption levels presents certain technical difficulties.

To ensure these oils are of a suitable standard, alternatives to the familiar API (American Petroleum Institute) service classifications have evolved. Alternative standards currently being used by Australian manufacturers include, ACEA (Association des Constructeurs Europeens dAutomobiles) and ILSAC (International Lubricant Standardisation and Approval Committee) service classifications.

See our information sheet Understanding Engine Oil Designations for an explanation of oil viscosity and service ratings.

Where a low viscosity oil is recommended by a vehicle manufacturer to derive the fuel efficiency benefits, this oil must be the prime recommendation for the engine. The maker isnt permitted to produce a claimed fuel consumption figure using one grade of oil and then specify a different oil grade for service.

Most lubricant manufacturers data sheets show their low viscosity oils as part of their semi synthetic or full synthetic range and they therefore tend to be more expensive.

Caution! Use of these low viscosity oils in older model engines, and engines not specifically designed for such oils, may result in oil consumption and engine durability problems.

The use of a higher viscosity or thicker oil in an engine intended for a low viscosity oil will increase fuel consumption and emissions and may result in engine and emission control system damage.

The vehicle owners handbook should always be consulted to determine the correct oil specifications for the vehicle. Major lubricant makers technical help-desks and web sites are helpful also.

Oil manufacturers have advised that low viscosity oils are compatible with ordinary mineral oils for top-up purposes, however, this will reduce the original oils performance. To avoid this top-up with the same product would be preferable.