I bought some cheap Greek Amo and thought it was great ,hardly any missfires and no duds , but got to talkin and it seems there is Salt added in Primer and or powder.
All primers and powders produce "salts" when they burn. They are not necessarily what one thinks of: sodium chloride (NaCl) which is what makes "salt" water so corrosive.
If you got real elCheapo Greek stuff -- help me out guys, is it "Olympic" brand? -- you may be faced with "corrosive" primers. Best cleaning solution is hot soapy water, followed by thorough drying, and then a light coat of oil. Back in the days when dinosaurs roamed the earth and all US ammo was corrosive, the Army had one do this for three days running.
The CMP stuff, "HXP," (also available from other sources: Orion 7 is one -- free plug) is noncorrosive primed. Hoppe's #9 -- I'm a traditionalist -- will work just fine. One cleaning day should be enough.
For corrosive ammo I use a small bottle of Windex. Squirt a bunch down the bore while it's warm and it will dry quick Then clean it right when you get home like Ben said.
Salt Free M1 
