http://www.machinerylubrication.com/Read/518/motor-oils
Here's an thought provoking passage in the article considering 5W20 weight oil:
"To determine if SAE 5W-20 oils provide the same level of protection as SAE 5w30 oils, Dagenham Motors in England, one of the largest Ford dealers in Europe, was consulted. SAE 5w30 is required for warranty purposes in England, and SAE 5W-20 is not even available. If SAE 5W-20 were better for both fuel economy and wear, why would Ford not recommend it for its same engines in Europe?"
Interesting fact considering Europe has notoriously cooler ambient temperatures and more stringent quality controls over oil manufacturers and testing procedures.
Here's an thought provoking passage in the article considering 5W20 weight oil:
"To determine if SAE 5W-20 oils provide the same level of protection as SAE 5w30 oils, Dagenham Motors in England, one of the largest Ford dealers in Europe, was consulted. SAE 5w30 is required for warranty purposes in England, and SAE 5W-20 is not even available. If SAE 5W-20 were better for both fuel economy and wear, why would Ford not recommend it for its same engines in Europe?"
Interesting fact considering Europe has notoriously cooler ambient temperatures and more stringent quality controls over oil manufacturers and testing procedures.