Been there done that high mg/ml stuff. It doesn't matter if you warm it...it still leaves you fucked up for like 4 days....I'll pass
I'm saying hot oil in the muscle doesn't sound ideal. I think room temp is fine, and for sure nothing warmer than body temp should be going into you.
I have little or no pain after I inject, or even in the days to follow. I just injected Test Cypionate yesterday morning and I feel nothing in my quad.