Originally Posted By: Doc Holiday
Originally Posted By: Drivebelt
ILSAC has a fuel economy test as part of GF-4/GF-5 motor oil test sequence. It is optional for API SM/SN.
Quote:
Wiki Motor Oil
The International Lubricant Standardization and Approval Committee (ILSAC) also has standards for motor oil. Introduced in 2004, GF-4[10] applies to SAE 0W-20, 5W-20, 0W-30, 5W-30, and 10W-30 viscosity grade oils. In general, ILSAC works with API in creating the newest gasoline oil specification, with ILSAC adding an extra requirement of fuel economy testing to their specification. For GF-4, a Sequence VIB Fuel Economy Test (ASTM D6837) is required that is not required in API service category SM.
If the oil passes the Fuel Economy Test it can be labeled as "Energy Conserving". Most HM oils are blended to a higher (thicker) viscosity (to help reduce oil consumption and make a more robust oil) so they can't pass the Fuel Economy Test and aren’t labeled as such. The fuel economy test is specific to the grade of oil, so the 5W-20 test is a different standard than the 5W-30 or 10W-30. The 5W-20 has to beat the 5W-20 reference oil, the 5W-30 has to beat the 5W-30 reference oil and so on …
So a HM 5w30 should give better MPG than a reg 10w30 EC oil.
No reason to expect that. HM 30 vs EC30 would yield the same results regardless of the Xw value.