Synthetic oil is not just motor oil as pointed out by Triedaq.
We use to have a Power Vent for the furnaces at one of the Duplex’s I owned. On it’s yearly cleaning the fan on the power vent REQUIRED a synthetic lubricant. Because of the heat…non synthetic lubricants wouldn’t hold up. 2 years later NG came to the area and I switched from Oil to Gas.
Of course not. Logically if you can take one “natural” petroleum based lubricant and make it from a mineral oil base to a synthetic base you could do it with pretty much any. That they’ve made it specifically for musicians is somewhat surprising as it’s not a huge population base so I wonder how much they make on it.
I just moved from a house with oil to natural gas…I am overjoyed that I no longer pay for heating oil…
I’ve always used thinner oil directly into the valves and thicker oil on the back and top of the rotor valves. (I think I’ve used 3-in-1 before for the back of the rotary valves as well and I’ve never had valve problems on my 8DS).
And in the all important move back to cars, all of my vehicles that have transported me and my horn have had synthetic oil in their crankcases 
We saxophonists lubricate our horns with non-synth bourbon.
It wasn’t until about 10 years ago that I saw my first synthetic lubricant outside of motor oil or transmission oil. Not sure how long they’ve been around.