I have no dog in this fight. I no longer own any Honda's (my daughter now owns the CRV in my last post), and it is unlikely that I will ever own one again. Nothing wrong with them, but I am an empty nester, a country boy, and honda's no longer fit my needs.
I completely understand the statement "why risk it...just use what Honda specifies". But, if we were all to follow that recommendation, then why even have this forum? Isn't a major drive of this forum to ask 'WHY?'. Do we not want to challenge the status quo?
I keep hearing over and over that one is nuts if they stray from Honda ATF. I keep searching for a TECHNICAL reason, but I can never seem to find it. All I hear is anecdotes. Honda transmissions are supposedly 'designed' different and 'require' their own fluid spec. That may very well be correct...but I would like to hear the proof and understanding behind that demand.
Short Story: my '14 Silverado is my first vehicle that has trans fluid temp available on one of its displays. Back in the spring, on a nice ~65degF afternoon, I made a 40mi drive across town. I made a point to watch the trans temp out of curiosity. I noted that it didn;t reach the 190-195 normal operating temp unil mile 38. Since the great majority of trips are less than 38 miles....I began to question the importance of a centipoise or two of viscosity. Even in the July heat wave we are having, it takes at least 15 miles for my trans to reach equilibrium temps of 190-195f. So, other than long trips, WHY is a Cp here or there so critical since our vehicle ATF temps are all over the place?
I undersrtand there are many more variables to consider other than viscosity. Just using that as an example..
No argument intended here. Just want to know the scientific reasons that some substitutes are not wise. Just trying to learn.....same as the OP..