Differences Between Car Motor Oils and Heavy Motor Oils

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There are many formulation differences between Motor Car oils and Heavy-duty oils from additives to detergents, dispersants, antiwear additives and viscometrics. Engine oils are specifically formulated and tested to optimise their life when used in the correct application.

What’s the Difference Between A Light Duty and Heavy-Duty Engine?

Heavy duty engines are not designed for speed but to produce the maxim amount of torque to move, lift or generate power depending on the final application. Heavy duty engines are found in many applications from plant, agriculture to trucks with the sole purpose of providing sustained power.

Car engines are for lighter needs, and they need to get people somewhere quickly and reliably. Car engines operate at higher RPM’s compared with heavy duty applications with lighter oils required to lubricate and cool. Some components are oil viscosity dependant, others are simply lubricated either way the choice of lubricant is essential for optimised engine life.

Can You Use Heavy-Duty Oil in A Car? 

Heavy duty engine oils should not be used in cars as they have not been formulated for lower duty applications.

Heavy-duty vehicles are designed to work harder and longer between oil drains. Car engine oils are typically changed annually or between 7,000 and 30,000 miles depending on the manufacturer. Heavy-duty engines can reach greater than 100,000 miles in long haulage applications. As well as this, heavy-duty engines need to be lubricated with oil viscosity levels such as SAE 15W-40, 10W-40 or in modern applications an SAE 5W-30 and deal with high levels of soot generated through combustion and EGR valves.

Soot thickens oils dramatically and hence they are formulated accordingly with high levels of additives. Modern car oils are usually in the ranges of an SAE 5W-30 to SAE 0W-20 with cleaner burning engines. Particulate filters are present on both petrol and diesel in more modern vehicles which are very sensitive to ash generated from oil additives.

Can You Use Motor Car Motor Oil in A Heavy-Duty Vehicle? 

Using car engine oils in heavy duty applications would be a costly mistake. It's not just because they have longer oil drain intervals. It's also because they almost always run on diesel, produce more soot, generate more torque and have a multitude of additional equipment to control pollution levels such as DPF, EGR, SCR to name a few.

A car engine oil will lubricate a heavy-duty application for a short while, but over longer periods will not have sufficient additives to control soot, reduce wear and protect expensive after treatment devices from early failures.

Weighing Up the Facts

For heavy-duty engines to last longer with reduced drain intervals, the oils they utilize have higher levels of detergent and dispersant additives. Their viscosity levels are also higher, which in turn makes them unsuitable for modern car engines with higher RPMs and thus, thinner oils are needed not only to lubricate but to cool and flow at all temperatures.

There are some oils that are essentially ‘half and half’ whereby they possess qualities of both heavy-duty and lighter duty oils. Now with tighter pollution restrictions the exhaust emissions of heavy-duty vehicles have been reduced from Euro 1 to Euro 6; however, this puts more soot loading on the engine oil and thus, make it dirtier. Heavy-duty oils are designed to keep plant machinery, Agricultural and Trucks running longer between oil drain intervals.

We highly recommend using engine oils that were designed for the task. Take a look at our heavy-duty oils such as our Taurus Range. Our Automotive oils are varied, so you can always get the specific oil your car engine requires. Please use our online oil look up for specific oil recommendations.


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