There is much dispute over this. Some say "the manufacturer knows best". Others say "This was a change to get an extra 0.1 mpg on the EPA test cycle". Based on the info that was circulating when this new oil first came out it was VERY hard for them to come up with an oil formulation for the 5W20 that provided the same protection to the engine as they were getting with the then current 10W30 oils. They finally had to go to a minimum of a semi-synthetic blend to get a 5W20 that worked as good as the old non-synthetic oil. In addition, if you look at Fords recommendations, they do NOT recommend the use of the
5W20 in several of their more mature engine lines but say to keep using the 10W30. So the bottom line is that the 10W30 (without even needing to use part synthetic) was good enough for 100% of their engines, but the 5W20, even with synthetic added, is still not good enough for some of their engines. My conclusion is that I'll keep using the 10W30, thank you very much, and others can save 0.1mpg and wear their engines out sooner. But if you feel compelled to use the
5W20 at least use a full synthetic like Mobile 1 rather then a blend. Many full synthetics have such a wide performance band that the same oil can actually meet both specs anyway.
Yep they really mean it and have meant it for many years now. Your Honda engine appreciates some spirited driving to give its best and will happily run almost forever on 5w/20 oil given a change every 10,000 miles or so.
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