I bought a Jasic stick welder some years ago & yes it came with a 5 year warranty. From what I recall, the only condition was to clean the dust out regularly. Don’t use it a lot, but no complaints so far.
for what it's worth, i've a little 160a Parweld rated 25% at 160, it runs 3.2mm sticks at ~130 all day long, so while I haven't tried 4mm on it, 25% at 160 sounds achievable
