Shifting weird, explain gear lube plz!

[Pimpin Dsmstyle]

I solved my lock up problem in my transmission. However, now it makes weird noises and small things I can feel. I suspect gear lube would be the solution. Can I get an explaination on why it does this? Also, I do not understand how to find the right gear lube. I dont know what the numbers mean. I also dont know what GR3,4,5 etc means. Does the kind get effected by cold weather? You can PM me information or post.