Hi,
Bob - Shannow has touched on this issue with his answer. It is quite complex as I see it. He also mentions CD which is still used in may circles and CF only replaced it on most API dual rated PCMOs within the last several years
Engine Manufacturers will apply their Approved Lubricant requirements if they are available. In some Markets Approved lubricants may be unavailable and the API designations take priority - such as this from a Driver's Manual;
"Use only oils labelled as API SM/CF 5W-40 or higher. Only synthetic or semi-synthetic oils should be used. If in doubt consult your authorised (????????) Dealer for tested and Approved all season oils."
The reason that the CF Category is being discontinued is that a prime test - Caterpillar's IM-PC - has only limited availability. It is not that the Category is "obsolete" in real terms. It is likely that CF did not reamin the same during its 16 years lifespan. There was also no "read acress formula" in the case of viscosity changes due to base oil comixing in this Category - this would have made recertification costly I expect. The API allows comixing of Groups I, II, III under certain condtions
So when the API's CF becomes obsolete at the end of 2010 I suspect that some Blenders will not move to use CG-4 for instance (as SM/CG-4) - perhaps they will simply use the appropriate ACEA Category or simply sell as SM once CF expires
It seems commonplace for motorbike manufacturers to use obsolete API Categories too - I suspect this is because many Blenders don't qualify their products to JASO MA and etc!
For me ACEA is the correct approach - the standards are set by the engine manufacturers!
Bob - Shannow has touched on this issue with his answer. It is quite complex as I see it. He also mentions CD which is still used in may circles and CF only replaced it on most API dual rated PCMOs within the last several years
Engine Manufacturers will apply their Approved Lubricant requirements if they are available. In some Markets Approved lubricants may be unavailable and the API designations take priority - such as this from a Driver's Manual;
"Use only oils labelled as API SM/CF 5W-40 or higher. Only synthetic or semi-synthetic oils should be used. If in doubt consult your authorised (????????) Dealer for tested and Approved all season oils."
The reason that the CF Category is being discontinued is that a prime test - Caterpillar's IM-PC - has only limited availability. It is not that the Category is "obsolete" in real terms. It is likely that CF did not reamin the same during its 16 years lifespan. There was also no "read acress formula" in the case of viscosity changes due to base oil comixing in this Category - this would have made recertification costly I expect. The API allows comixing of Groups I, II, III under certain condtions
So when the API's CF becomes obsolete at the end of 2010 I suspect that some Blenders will not move to use CG-4 for instance (as SM/CG-4) - perhaps they will simply use the appropriate ACEA Category or simply sell as SM once CF expires
It seems commonplace for motorbike manufacturers to use obsolete API Categories too - I suspect this is because many Blenders don't qualify their products to JASO MA and etc!
For me ACEA is the correct approach - the standards are set by the engine manufacturers!
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