Gear oil for trans and rearends

[Rawze]

(02-04-2017 )386lover Wrote:  Could you explain what you mean by "in neutral"? Are you saying that if you are not actively accelerating, that you take it out of gear? Or am I misunderstanding you?

Absolutely.

Truck has 1.03 mil on it. I finally replaced my clutch, input shaft, ipt. shaft bearing, rear motor mounts, rear main seal, had the flywheel turned, replaced the mid-shaft bearing, and replaced all the u-joints on the front drive shaft. This is the first time everything has been apart.

My old clutch still had half its life left on the pads. About 25% of the end of one of the springs had failed and snapped off. It was rolling around in there, and that is why the clutch started acting up. It made it difficult to get into gear at times randomly. - At a million miles, I simply replaced everything relevant to having it apart out of safety concerns.


- While the tranny was out I had the top plate removed and the insides looked at very closely. They tried their damnedest to find some excess wear in it from running it out of gear its whole life. -- There was less wear in that tranny than any he had ever seen with only 1/4 the miles on it. In fact, he said there was less wear than a fresh re-man tranny on the inside. He went out of his way to find some wear and effects from me driving it in neutral its whole life. -- Even the play from the gears to the shafts were checked. -- Like new still.

BTW: I run Shell 75/90 synthetic in my tranny (and rears). He said every tranny they have had apart where someone runs 75/90 in them, they always have less wear than people who use only 50-wt oils.

Input shaft after million miles+ ..
   

Forks, still no wear after million miles in mostly neutral ..
   

We have 10-speed tranny and we shift between 9th and 10th gear about 200-300 times a day, and keep it in neutral unless we have to make power to get back up to speed. We do this every day and have since truck was brand new. It is because we drive 55-57 and coast absolutely as much as possible to save fuel.

Here is the actual results ...

Close-up of 10th gear after million miles (the smaller gear in the middle) ..
   

Close-up of 9th gear after 1 million miles (the smaller gear in the middle) ..
   

Here is an overview of the rest...
   


======

That is what the results are. You can see a tiny bit of wear from use, but nothing that would indicate anything harmful at all.