New Owner, Humbly Looking for Guidance

Well, my son had a golf cart break down today so i had to take the ATV out right after work and drag the golf cart home. I'll deal with fixing that later.

I just did a few things that are easy to do. I aired the tires and removed the horrible wheel covers. The black wheels underneath look mo' bettuh. I noted bulb numbers for those that need replacing. I aired the rear shocks. They call for between 25 psi and 200 psi. They had 0 psi. So I aired them to ~100 psi. It lifted the rear end 3 inches.

I checked the air filter, it looks new. The carburetor is a 750 cfm (not 600 as i guessed). I checked the coolant ... uh ohhhhhh! Way way low. But i could see some wetness near the top so at least there is SOME in there. I'm glad I only ran it minimally. I added some 90 octane no ethanol gas which is what i buy for my mower and dirtbike. I will be looking for higher octane no ethanol, but i don't think I'm going to find any. These engines stock run (from memory) about 8.4:1 compression so 87 octane would be ok. But this engine is not exactly stock. But I doubt it's high enough to need 93 octane. I take it back, I saw some like 114 octane no ethanol gas on the puregas website. I suspect it's race fuel and not necessary.

Tomorrow I'll get some bulbs and coolant. And maybe some oil, an oil filter, and spark plugs if I get some feedback here or find some info online. I heard that diesel engine oil was good because it has a better ability to suspend particles in the oil (i.e. soot). Once suspended it gets carried to the filter. And this old engine, and especially since it sat around so much, probably needs a lot of crap carried to the filter. So, unless someone says different, I will be using Valvoline Premium Blue 15W-40. I will run it 1,000 miles and do another oil change.