The log splitter that I bought from TSC came with 1/2" fittings so I used 1/2" hose, and two 1/2" - 3/8" reducer fitting I had in my cabinet of many things...
The log splitter needs 6 - 7 GPM and a 3/8" QC can flow at 7 GPM, so I could have reduced at the splitter but TSC was out of 3/8" so I bought what was on the shelf (1/2")
If all you are going to do is lift a bat wing or something like that you can go with smaller lines...