When the oil light comes on in a near new car it’s normal to ask why? In most cases the oil just needs a top up, which poses some important questions… What’s considered to be ‘normal’ oil consumption? And what are the factors that influence consumption?

Before we explore why oil consumption occurs, it should be noted  that a level of consumption should be anticipated in all engines. This is a common fact that is communicated by the car manufacturers themselves, and published in owner’s manual.

As an example a 2008 VW GTi owners hand book explains that “It is normal for the engine to consume a certain amount of oil. Depending on how you drive and the condition in which the car is used, oil consumption can be up to 1.0L/1,000km”, so topping up small amounts between services is considered acceptable and should really be expected.

Engine oil consumption can depend on a number of factors, typically late model more advanced technology engines run at hotter temperatures to increase engine efficiency and reduce fuel consumption & emissions, high operating temperatures often cause an increase in oil evaporation loss and an increase in oil consumption. Combine a high operating temperature with a low viscosity oil (which most engines are now being spec’d with) like a 5W-30 or 5W-40, and it’s inevitable that oil will escape past moving parts and sealing rings at a higher rate. Design and operating scenarios aside, the following engine problems can also cause oil to disappear at a high rate:

• Defective or clogged PCV (positive crank case ventilation)
• Bearing & general engine wear
• Cooling system problems/engine hot spots
• External Oil leaks
• Engine sludge and clogged oil galleries
• Cylinder Glazing
• Over filling
• Incorrect oil

These are all things that can be diagnosed by a dealership when under warranty or a specialist repair workshop.

The average car takes between 5-6 litres of oil, when the oil needs to be topped up by 1 litre (a volume that makes up a significant percentage of the overall oil capacity) it’s definitely NOT ideal. Regular checks of the dipstick is the best way to keep an eye on the oil level and is far better than seeing the oil light come on. Thankfully you can rest assured that the car manufacturers have engineered the oil capacity to adequately cover normal consumption and the warning level. A guide to what the oil level should be on the dipstick for all cars is published in the owner’s manual.

When topping up the correct specification or approved oil is needed, using the Golf GTi as an example, it requires the VW 502.00 approval, which is carried on numerous Liqui-Moly products like the Top Tec 4100 5W-40 or the Liechtlauf Special LL 5W-30 , both are available in top up sizes of 1L. Keeping a 1L spare on the garage shelf or in the boot could come in handy if you ever get caught out. Check out the Liqui-Moly online oil guide to find the correct oil for your car.