The PQIA recently purchased three brands of SAE 10W-30 motor oils in the south, and the results of the tests conducted on the products meet the SAE J300 specifications for the SAE Viscosity Grade listed on the product label, and are consistent with the listed API Service Categories.
Although SAE 10W-30 accounts for only about 10% of overall passenger car motor oil demand in the US, PQIA finds this viscosity grade is more prevalent at retail stores in southern states, where the samples tested were purchased, than it is in other regions of the country. In fact, it is the dominate grade on the shelves in some of the retail stores visited by PQIA in the south. In addition to a higher showing of SAE 10W-30, PQIA typically observes a disproportionately higher percentage of mono-grades, as compared to other regions of the US. Based on anecdotal evidence, some consumers in the south prefer higher viscosity grades and mono-grades because of the hotter climate in the region.
It’s important to note that although some car manufacturers recommend use of only one viscosity grade in the vehicles they manufacture, others provide vehicle owners with options based on the ambient temperature where the vehicle is operated.
For maximum engine performance and engine protection, car owners should always refer to the owner’s manual for proper SAE viscosity grade, API Service Category, and other specifications recommended to service their vehicle. Importantly, use of a motor oil other than that specified in the owner’s manual could void the vehicle manufacturer’s warranty.