What people don't realize is that when using synthol or other SEOs, unless you want to look very obvious (and sometimes very crappy) it is often a two person job.
I have never used it personally (synthol - but do site inject not for the enhanced look but to simply stagger out my inject locations) but I do know some that have used it and you honestly would never know they did, even at close inspection. Note that I said "used it" which is completely different from "abused it".
The three major mistakes that people make when attempting to use it are :
1 - Not going deep enough into the muscle
2 - Not staggering it out with multiple sites each administration
3 - Not massaging it long enough or properly
Most people doing biceps don't use a long enough needle. You got to get that oil wayyyyy down in the muscle so it swells from within and not just "floats" on top between the muscle/fascia/skin where it gives you the giant mosquito bite look. It's painful. Deep muscle with plenty of nerves. You need another person to administer it in case of a twitch or in case you pussy out and stop half way.
You can't just dump the whole volume being administrated into one location either. You got to break the volume and put it in different places to spread it out. Even a small muscle like the biceps needs about 6-7 different sites hit every single time you use it.
When it comes to massage, most people simply just rub the muscle for half a minute and move along with their day. You got to put more effort than that in it. Hard massage, deep tissue for at least 10 solid minutes per muscle. But people don't do it. Don't know why... you can sit on the couch and do it while watching DWTS

I have often wondered why some of these people are not dropping dead from heart attacks due to the sheer volume of oil they are pumping in their bodies. Yes, the compound breaks down slowly over time, but I think that the muscle itself goes into a defensive mode and (rightfully so) treats the SEO as a foreigner invader and encapsulates the area being abused to protect the body from it spreading.