“I was tought that if it looked icy or if there was snow on the road you put it in 4wdh I once had a Taho that had the auto 4wd which I left it in if the road was ok but sometimes not. However if the road was straight up bad I put it in full time 4wd and I know at times I was in 4wdh at over 50mph”
“Whitey” has my vote.
Not only may if be difficult on your drive train (though it varies from make to make), but it’s just plain unsafe with part time 4 wd. That’s why many trucks have added auto/awd feature.
When you lock in your steering wheels, you lock in, not only engine braking, but drive train drag at about 50%. This could cause loss of steering control and is the primary reason so many 4 wd leave the road. Leaving it in 2 wd on the highway at higher speeds will not only encourage caution, but you have a better chance of retaining steerage in a skid. The ability to accelerate to higher speeds in 4 wd is a false sense of security. For safety sake 40 mph or less for me in part time 4 wd. You can “feel” the cornering and braking limits of your truck if your acceleration is limited as well. That extra momentum at speed cannot be overcome by the disadvantages of part time 4 wd.
By the way, I hope you have plenty of weight in the bed (tube sand). It’s more necessary for handling balance than even a 2 wd truck with 4 wd added front differential. Another important neglected factor in safe 4 wd operation.
Please realize the dramatic difference at speed between a good awd system (not often found in trucks) and part time 4 wd that you have. Part time 4 wd is for low speed. heavy duty use. AWD is all speed light duty. Slip it into 4 wd on hills to maintain speed less than 40 mph, IMO. My 4Runner has an awd feature that I am still reluctant to use above 40 mph like my Subaru or RAV awd.
The most unsafe vehicle you can drive in slippery conditions I feel. is a part time 4 wd with no weight in the back and poor tires.
The extra understanding of how and where to use 4wd is not found completely explained in an owner’s manual…my hat’s off to you for asking questions and doing research before you have an accident.