Originally Posted By: userfriendly
API classifications so far have been backward compatible. That does not mean SAE grades are backward compatible.
That's why we do have to watch specifications. When you look at a gasoline engine calling for an SN/GF-5 oil, it's going to call for at least one viscosity, and perhaps only one for all year use. Obviously, at least in a significant number of applications, you're not going to dump in 0w-20 in place of 5w-30. Not only is SAE grade different, you'll have a lower HTHS.
At least the CJ-4 stuff and builders approvals get you to the minimum HTHS for the engine's requirements. That's seen in plenty of European applications Of course, one should still not discount what the manufacturer says in the manual just out of hand.
API classifications so far have been backward compatible. That does not mean SAE grades are backward compatible.
That's why we do have to watch specifications. When you look at a gasoline engine calling for an SN/GF-5 oil, it's going to call for at least one viscosity, and perhaps only one for all year use. Obviously, at least in a significant number of applications, you're not going to dump in 0w-20 in place of 5w-30. Not only is SAE grade different, you'll have a lower HTHS.
At least the CJ-4 stuff and builders approvals get you to the minimum HTHS for the engine's requirements. That's seen in plenty of European applications Of course, one should still not discount what the manufacturer says in the manual just out of hand.