25 and 36-inch bar on a 462 Stihl vs 32-inch walnut log. Which one was faster? 

I stick to a 25" even on my 661 but Australian wood is harder than woodpecker lips and I have the luxury of an 881 with a 42" bar if it really gets past words.

36 inch bar needs adequate oiling ,u chain looked pretty hot there !

Spot on ! Very little that can't be done with a 24 " bar . Stand up and buck hahahaha

Log bars here in the Midwest is usually in the way. Unless big bottom timber. I like my 24" on my Husky. Just me.

36" bar puts a lot of pull on the saw, 25" bar let's the saw stay up it's power range I guess is what ya call it. A Stihl is capable of lugging down and pulling back up pretty quick. But unless you modded the saw I personally don't think it's worth putting the 36" on and running all day not counting the extra weight of the bar. Just my opinion, stay safe out there!

what do you think about a 20" bar on a 462 as an option to the 25" it came with? No need to go bigger than 25" for what I cut

Here in the Pacific Northwest coast of the united states or British Columbia the trees require the long bar and you don't have bend over as much . Ported saws have more power !

I don't like big bars either. To unwieldy and throws the chain easily. I run 18 to 28. Bigger ones hang on the wall and don't get used more than once in a blue moon. Stay safe tree men.