Sooo I bought a logsplitter on craigslist (homemade rig), and went to pick up some hydrolic fluid for it. I didn't realize there were so many different types. I bought AW 32. I have no idea what the proper kind to use would be. How much does it matter? Are they fairly interchangeable? Haven't put any in yet in fear that i could maybe do some damage to the cylinder.

That will work just fine

aw32 is plenty good for a log splitter, they say that’s about a 10weight oil. Good flow even in cold weather. If your really concerned see what model pump it has on it and see what they recommend. Any universal hydraulic fluid is fine in my opinion for a log splitter. I’ve had my log splitter almost 20years and i’ve changed the filter a few times but never the fluid and it still works great.

the pumps on splitters are all fairly similar it isn't like your trying to lube a transmission in the tractor at the same time

my splitter came with a temperature range chart for selecting the oil

-20 to 32 above Dextron VI
10 to 60 AW-32
32 to 80 AW-46
50 to 100 AW-68

I find splitting to be best for me 10 to 60 I run the AW-32

I have split down to 0 but it sure starts hard in the single digits if I can get it warmed up a bit then it is fine

some times setting it in the sun is enough if it is clear and 5 and sunny with no wind the tank is black