Ok before i get abused- I HATE SYNTHOL and would never use it. but have a read of this:
"How do Site Oils work? To begin with, they do not stay in the muscle for 3 to 5 years. They get dissipated within months. However, during this time, they have stretched the fascia of that muscle. The fascia is a great constrictive factor in muscle growth. The more stretched the fascia is the more the muscle will grow and the more it will have that `popping' look. Site oils stay in there long enough for the fascia to stretch. As they dissipate, the `space' left by them is replaced with new muscle tissue growth. That is the reason why when x-rays/MRIs where performed on some of the people that have 25"+ arms, there was no oil found in there. The oil dissipated and it was replaced by real muscle.
The principle is the same as the one behind site shots with steroids, but it works at a much a larger degree, because the Site Oils take that much longer to dissipate.
As well, this is the same principle behind fascial stretching. Howver, it is much more efficient with Site Oils. Best example is to imagine a baloon. You can pull on it and stretch it as much as you want, and you will stretch it a bit. But if you fill it with a liquid, you will be able to stretch it to a much larger degree than just pulling on it from the outside. This is the best way to compare the efficiency of fascial stretching versus using Site Oils."