IHC find

A friend I hadn't seen in a while produced a 4.6 IHC (mixed master) and I checked it out. I was working so it was quick. It had WWII trig housing SA ,trig guard, and bolt SA,the barrel was ?- 52 that's all I could see and the op rod was IHC. What my ? is, the receiver is green but like light green dark green in a tarnished almost camo(discolored) look to it. I know its from neglect from before my friend got it. Is there any thing that can be used to clean it up or does it just need oil.(it was a drill rifle and now a good shooter) Any help out there is appreciated. Also the logo is Postage stamp. which logo is more rare?

Is the "camo" effect somewhere in the middle of the rifle? If so it may be a welded-repaired receiver. Make sure the front half says IHC on the side. If it says another manufacturer, it is a repaired salvage job. You did say it was an ex-drill rifle; that is worrisome if it got too much heat up front where the barrel may have been tack welded, which could be indicated by weird mottled coloring, safety of the rifle could be open to question.

Wiping down with any light oil should solve the problem on a normal rifle.

I will check that if I can look at it again. the discoloration is all over the receiver upper not what is cvered by the stock. this is Florida so it may just be corrosion typical to neglect in a hot humid climate 10 months of the year. Oddly enough when I looked at it I did check for any weld mark to see if it was welded back together and all looked good. I once sold(for a friend) an inherited 400000 # SA that was welded at barrel and gas cyld. I didn't know what it was until the gun show. sold it to a reanactor and my friend was happy. the IHC I'm told shoots great but if I look at it again I'll let him know.