Omc 3.8l v6 800-what types of oil to use?

I just drained the upper and lower as well as the tranny to see if there were any shavings. Luckily there was none. I need to know what to buy to r we place each chamber. I did this because I am having trouble with reverse.

That box behind the engine (called the intermediate), contains nothing but a straight shaft with 2 bearings.
the lower unit is your "tranny" and all shifting takes place at the propeller shaft just like an outboard, but cable operated

anyways, all 3 compartments take 80W90 gear oil in most climates.

So maybe you can help me with my reverse issues. The shifter will go in forward just find. Although the shifter handle, for some reason, does not sit in an upright position when inbetween forward and reverse. It's almost half way into reverse when it's in the nuetral position. Any, with it like this i can put it in forward no problem but can't get it to go in reverse because i have to push it back so hard, the engines idle goes up and if it did engage, we would be thrown to the front of the boat. I took the cable off at the plate mounted to the engine and tried to put the boat in gear by hand. When i push it toward forward, it's easy. When I push it into reverse, I have both hands with alot of muscle and still barely get it into reverse.
After some research online, I was informed to check my oil to see if there were any metal shavings. That's why I drained everything. Luckily, only one small metal flake was found. Now I just need to find out what I can do to un bound the reverse. Please help!!