you aren't going to get it deep into the muscle with a 1/2 inch needle + you are squeezing oil through a tiny needle + you aren't going to be able to load much into a small syringe. it is much more efficient to use a 25G and 1 inch needle.
however as said above I have used slin pins to inject many compounds, the only one that wouldn't work for you is if you used pharm grade primo.. that shit is way too thick.