This comes up all the time.
The main problem is, lots of the car makers switched the 205 from gear lube to automatic transmission fluid in an attempt to reduce parasitic loads and get more gas mileage
The nice thing about the 205 is its fairly open and crude. Just big bearings and helical cut gears.
It doesn't need finicky lubes to get into tight places or handle high speeds with no foaming.
It just needs good solid lubricant between the gears.
When I first heard about using ATF, I figured the boxes would last about long enough to get out of warranty.
But, ATF is some amazing stuff. One of the most complex lubes ever made. And I have seen 205s go a long time on it.
In general, autos do not see the point gear loading that a 205 does. They mostly use planetary gearsets that tend to split the load among several gear teeth. A 205 tends to concentrate the load.
That is why I prefer the heavier oils.
As for the weight, they are fairly forgiving. Too heavy should not be a problem as long as it can flow.
Cup grease is not going to fly, but anything reasonably liquid should do the trick. But, the heavier the grease, the more the running load to a certain extant.
Plus, if you are going really cold, you need to be sure it will be nice and fluid when it first starts up. If its like molasses, you are going to have problems.
I always ran 85W90 in mine, until I discovered the joy of synthetic.
It was normal after a run to the farm on the highway for the transfer case to be too hot to touch comfortably.
I could feel the heat through the floorboard with no carpet, and if I crawled under, it was really hot.
I switched to 85W90 Amsoil, and it cooled down to just over warm with no other changes.
I run Amsoil in everything except for the Auto Tranny now, and like it a lot. I don't know if it helped much in gas mileage, or even wear, but the heat factor difference is huge, so it has to be doing some good.
Note: I use Amsoil, because they pretty much invented the stuff, and I have a friend who is a dealer.
Most of the other brands are probably just as good.
Also, I have heard of some manual transmissions that do not shift as well with synthetic because the gears spin too well.
They normally use the grease to slow them down so the syncros do not have to work as hard.
Don't know of models, but over the years, I have heard that info.
I don't think the 140 will hurt anything as long as it flows at your max low temp. It should, that is what the "W" number is for.......
