Shift! **** You Shift!

Grit dog wrote:
Swimmer, stop and think about it. Yes the transmission programming is pretty good, but your truck does not have eyes in the grille to see and anticipate the next curve, hill, up or down, slower moving vehicle etc.
Only YOU can do that. Know that it will not hurt to lock out a gear or 2. It will actually help. So either be upset at your "dumb" vehicle or be upset at yourself for not understanding the concepts fully. Remember, you came on this thread basically bad mouthing your truck that was/is doing exactly what it's supposed to do when you actually just don't understand what to do. The last part is fine, we all need to learn. Not everyone has been towing and operating large vehicles and equipment our whole lives.

Your expectation seems to be that the truck should essentially drive itself. It doesn't.
You've received help in this thread and seem to constantly rebut it. That is what sparks the sarcastic comments. Plenty of folks here that know a thing or 2, plenty that just pretend they do, and a few that will admit they are truly looking for advice or direction.
Hard to sift thru bs vs good advice simply by the written word, but I think you can find the good advice. You just need to take it.

Yet no one has given me an explanation why it didn't do it with a heavier trailer.

The more and more I think about it, the more and more I think something is not working right, as apposed to my driving skill. The heavier trailer should have been more of an issue, but crossing Canada (4000km) it pulled like a dream. It would sit in 6th at 110 km/hr. Now, a lighter trailer, at 100km/hr it is hunting.

So, excuse me if I take issue with someone saying "just don't use the top gear".

Which is why, yes, until I get it checked out, I will tow in 5th. However, this does not mean I should.