What ILSAC GF-6 covers
ILSAC GF-6 is a standard for gasoline-engine oils developed by the International Lubricant Standardization and Approval Committee. Its emphasis is on fuel economy together with engine protection, including resistance to deposits and wear in modern engines. Oils meeting GF-6 are intended to deliver these benefits over a normal service interval when used in the engines and grades they are specified for.
A defining feature of GF-6 is that it is split into two sub-categories. GF-6A covers conventional viscosity grades and is broadly backward compatible with applications that called for the earlier GF-5. GF-6B is a separate branch created specifically for very low viscosity 0W-16 oils, reflecting the move toward thinner oils in some newer engines.
ILSAC GF-7 is the newer standards family. GF-7A follows the main Starburst branch, and GF-7B follows the separate 0W-16 Shield branch. See API SQ and ILSAC GF-7 for the current label pattern.
How it relates to viscosity and API
The GF-6 standard sits alongside the viscosity grade rather than replacing it. The grade — such as 5W-30 or 0W-16 — describes flow behavior, while GF-6 describes the performance level the oil has been tested to meet. An oil should satisfy the standard your manual lists AND the correct grade.
GF-6 is also designed to work in step with the current API gasoline category, such as API SP. For that reason many products display both an ILSAC mark and an API category, since the two sets of requirements overlap but are not identical.
What to follow
The most important rule is to match what your owner’s manual specifies. If it calls for 0W-16, the GF-6B branch applies; for other grades, GF-6A is the relevant one. Because GF-6B is tied to 0W-16, it is not a drop-in replacement for thicker oils.
When details are unclear, treat the owner’s manual as the authority for both the standard and the grade your engine requires.