Thor Forums

[EA37TS]

Food for thought, explained by Mobil 1, for those that may not know about oil viscosity.

What is oil viscosity and what impact does this have?
Viscosity is a measure of the resistance of a fluid’s flow. The thicker (high viscosity) of an oil, the slower it will flow.

Most oils on the shelves today are "Multigrades", which simply means that the oil falls into two viscosity grades (i.e. 10W-40 etc). In a 10W-40 for example the 10W bit (W = winter) simply means that the oil must have a certain maximum viscosity or flow at low temperature. The lower the "W" number the better the oil's cold temperature performance.

The 40 in a 10W-40 simply means that the oil must fall within certain viscosity limits at 100°C. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number, the thinner the oil: for example, a 30 oil is thinner than a 40 oil at 100°C.

In a cooler climate someone may have better luck with a 5W20 than someone that is in a warmer climate. Also, the more wear that is on an engine the greater the need for a higher viscosity oil.

Quite a few owner's manuals today still include a matrix that recommend a different oil viscosity based on temperature or operating conditions.

Again, food for thought.