I do my own work on my vehicle and if I need to use an air compressor at my realities house but now I thinking of getting my own. I don't need it all the the time but it would be nice to impact my tires off. I'm thinking between 20-30 gallon portable 120 15 amp range but what's your guys input. Oil vs oil free?

 

I have one of each.. I have a twin oil filled 80 gallon in my shop and a oil free 30 gl in my wife's garage.
I find the smaller oil free will create more water (condensation) in the air easier then my oil cooled 80 gl.
bigger is better. If you can get the smaller 110 volt in a oil cooled I would go for that added expense. better in the long run.

 

Personally, I'm a mechanic by day and a lazy sleep aholic at night.

Seriously though, I use a 30 gallon Husky oil free compressor, and it does everything I need it to do (run my professional IR 2135 Ti Maxx, snapon air hammer, die grinder, 3/8ths impact, snapon air ratcher, etc) and never goes below 100 PSI. The die grinder will take it down a little past 100 if I'm really rough on it, but the pump is enough to run my tools even if the tank is a little low. I can use the gun to take wheels off without having the compressor kick on.

So 30 gallons is a great size for my use. I just tried to give you a gauge of what I do with a 30 gallon. If I had to do it again, I'd get a 30+ gallon and an oil pump, just because I feel better being able to maintenance it. But my oil free has been fine so far. It's not very portable though, being so heavy. I got my Husky compressor for a huge bargain though but if it ever dies on me, I'll replace the pump with an oil pump from HF or similar as long as the specs are comparable.