Guys were using oil before synthol...Some of these bozo's would take a 100ml bottle and put 50ml's of Esicline and 50mls of assorted oil(MCT, grapeseed, cottonseed ect) and shoot in the muscle. Usually arms and calves...The dude Clark who came up with Pump-n-pose didn't pull the idea out of thin air. He just made a product he knew would work and sell because he knew what guys were already doing...The first year Pump-n-pose came out, Jay Cutler allegedly was using as much as 100ml a month...Shooting oil goes back as far as the 70's.
I believe in an interview Clark had said that Flex was interested in it.
Jay Cutler won his pro card in 96. And even as a NPC competitor his arms, delts have always looked the same. I'm not saying he didn't do it, I am saying whatever he did it didn't change his look.
You guys are right. Greg Valentino was the only bodybuilder with access to oil in the 90s. 

Gregg Valentino was mid 2000s.
Paul Dillett was West Coast. Esiclene was big with the West Coast boys (Flex and company) and Kevin Levrone.
From what was told on here, the supply started to dry up because several Pros were buying up or using almost all the product on the market. I don't know the full the story or if that was true or not.
What is true, is that Dillett eventually had shoulder issues, and had several operations. He mentioned in an interview that the doctors said that he literally had no more cartilage left, it was bone on bone.
This possibly means that he had ground down his cartilage? Which would point to him actually training shoulders. It doesn't mean he didn't shoot up his delts. But, it does point to someone who trains shoulders more than relying on foreign substances.