Air compressor oil

[road_rascal]

I picked up a clearanced as-is floor model 2hp 4gal (twin stacked air tank style) air compressor from Checker Auto last week (Alton brand - no manual, box, no online manual either.). The pump takes lube oil, but how much should I add? There is a sight glass- should I go 1/2 way, 3/4? I tried to find other lookalike models on the web but they all have dipsticks and this one just has a fill plug. Hey, for $30 I couldn't go wrong.

 

[Wrehch]

1/2 a sight glass is the fill level on all of my compressors that have them.

 

[road_rascal]

Thanks

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