What is the JASO valvetrain wear requirement? Is it a significant test for oil to meet? It seems that only better oils and synthetics pass it. Virtually everyone lists the GM, Ford, or Chyrsler specs they meet. And those that meet the ACEA or Mercedes Benz specs are sure to list those too. Every Ford I've owned points out in the owners manual that oil used should meet their WSS-M2C-specs, but I've never seen a Japanese vehicle spell out the need for an oil to meet the JASO specs. And then there is Castrol...they just say an oil meets the Japanese "engine wear" tests. Is any of this really important, or just more marketing noise in the system?