Heavy oils "work" in Hondas, i.e. there may not be any problems associated with using them, but I'm not sure what people expect to gain from using them nor do I think they often fall into the optimal, or even nominal categories. Note I do not include HDEO in that comment, merely the range of heavy viscosities commonly found in the HDEO category. The add packs in HDEOs are a separate argument, but one I am less inclined to argue against
People seem make these choices on the fairly intangible basis like, "I'm a thick oil man!", not as a cure for a documented, existing problem or a situational need. I speak only on Hondas used in a "normal" manner. I can completely understand special situations, such as extreme conditions of heat, cold or use that could dictate a visc change. But most of the people I see on BITOG are just doing it, seemingly, just to do it. Akin to, "Good enough for Mario Andretti... good enough for me."
I do not wish to insult anyone but I can't see how one can look at most Hondas objectively and reach the conclusion that a 15W40, 20-50 or 10W50 is an optimal choice on an engine designed for 5W20 or even 5W30. How many milliions of dollars has Honda put into R&D and validation on engine oils? How much collective experience and education do their engineering people have? More important, since when isn't 2-300K miles on the oil reciepe Honda selects not "enough" for anyone... and how can you prove a change is beneficial?
