Don't do it. So many older guys regret Synthol use.
I've yet to meet someone that doesn't look like the fucking Michelin Man advocate synthol use.
The scar tissue is real. Your tendons will tighten around joints that you use it on. You will at some point have an inflammatory response that will be quite obviously not regular swelling. At this point you will probably also get a fever.
And again, the primary message here is that the scare tissue only accumulates. Just like AAS, but the rate and mechanism through which Synthol is metabolized will result in stiffness, inflexibility and acute scare tissue accumulation.
If you want your arms that much bigger, just train them 3 times a week and spend the extra cash on AAS. 1st week will suck, by week 3 you will have noticeable results on a Gram of T or more.
Don't use synthol as a crutch, it's only a matter of time before you skip arms, shoulders, w/e and say "I'll just pin some synthol, swole as fuck no big deal." Fast forward a few years and you will look and feel like shit, and that is a god damn guarantee .