Over the coming weeks we will be publishing an informative guide to automotive engine oils.
Viscosity measures the thickness of a fluid.
Most modern oils are Multigrade oils which means that they fall into 2 grades of viscosity – 0w/30 etc. These were developed to enable engines to run on the same oil through summer and winter. The W number in the grade points to the low temperature performance, thus the lower the W number the better the oils cold start/cold weather performance. The 30 in an 0W-30 indicates that this oil will fall within a defined viscosity limit at 100°C for it to meet the stated grade. This number indicates the thickness of the oil so a 5W-20 oil is thinner than a 5W-40 oil and so on.
As oils behave differently at high and low temperatures these additive infused multigrade oils behave more consistently across temperature ranges to offer both protection and performance for your engine. The appropriate grade for your car will be stated in the owner’s manual and likely on the oil filler cap in the engine. If you have any questions your mechanic can advise, or, contact you local Gem Oils rep: