Is my deca still good?

I have some deca left over from a previous cycle and I was wondering if it is still ok to use. Its been sitting there for about 6 months now and there's about 4cc's left. It isn't past the expiration date yet but I'm not sure if it'd still be ok after being opened and sitting there that long, I mean wouldn't the air that you put in the vial before you are about to draw some out ruin it? Will it maybe just be not as strong or is it perfectly fine? I just don't want it to go to waste. Thanks for any info you can give on this.

I think if it was me bro I would bin it for the sake of a few quid

Billy