Thinner synthetic motor oil won’t damage your engine, but could save you money.

There are several engine oil myths surrounding using a thinner synthetic motor oil in engines: Often these revolve around older engines, and the use of the ultra low viscosity engine oils.

When a thinner synthetic motor oil will not be appropriate.

Using thinner synthetic motor oil, such as 0W20 in old engines that were specified to run with 20W50
or something similar, could cause problems. Not because of them being synthetic, bust because the viscosity would likely prove too low, creating problems for any components that rely on boundary lubrication.

It’s worthwhile to remember that high quality fully synthetic motor oils, such as that supplied Habot Synthetic Lubricants, will usually have superior shear strength when compared to regular motor oil, thus making them perform better under boundary conditions.

When to consider using thinner synthetic motor oil.

It’s important to understand that when we refer to using thinner synthetic motor oil, this is always with reference to the specified regular crude based engine oil.

The reason a thinner synthetic motor oil can be used without causing any problems (And in actual fact the lower viscosity when cold holds definite wear advantages over the thicker engine oil) is that it’s more stable over a wide range of operating temperatures. Previously a higher viscosity oil would be required because mineral oils thin out significantly when hot: This is not the case with the thinner synthetic motor oil.

So instead of using a 20W50 you could quite safely use a 5W30. This statement is made purely based on the lubricity of the 2 oils.

With older vehicles it’s important that engine oil seal material be considered: Some older seals are not compatible with PAO’s and could swell and eventually fail.

Advantages of using thinner synthetic motor oil.

Firstly thinnner syntheic engine oil is the best low temperature oil and cold start wear is significantly reduced using the less viscous oil. Secondly thinner synthetic motor oil reduces drag on engine internals such as the crankshaft – this means fewer losses, improved efficiencies which lead to more power and reduced fuel consumption.

Because synthetic engine oil doesn’t oxidise as quickly under elevated operating temperatures oil change intervals can be extended.


Using a quality thinner synthetic motor oil is good for the environment and can extend not only the oil life but also the lifespan of the engine.