For those interested there is a great history of how the specification for one of the most fundamental attributes of engine oils evolved in this Month's LubesNGreases Magazine
Link
Some highlights - a published version of the current testing limits of the J300 (including SAE 8, 12 and 16). Also a good history of how the cold temperature portion of the oil grade (the xW part) was developed and changed over time.
Understanding this history may help people better comprehend the nature of the 2 parts of the grade assigned to a multigrade engine oil (the cold weather performance and the operating temperature performance).
Link
Some highlights - a published version of the current testing limits of the J300 (including SAE 8, 12 and 16). Also a good history of how the cold temperature portion of the oil grade (the xW part) was developed and changed over time.
Understanding this history may help people better comprehend the nature of the 2 parts of the grade assigned to a multigrade engine oil (the cold weather performance and the operating temperature performance).