Hey gang, after 45 years in the automotive industry and dealing with sealants/adhesives and how to remove them on a daily, "in the trenches" basis, here are some of my favorites.... The aptly named 3M General purpose adhesive remover, either spray or quart can, often with 3M scotchbrite red pads. WD40 can be very effective in the right situation, again with scotchbrite or wire brush. Professionals hate silicone sealants because you must remove 100% of it for an effective reseal with the correct product. Nothing is really a solvent for silicone but many can act as an effective lubricant to help speed the job along. I have never heard of or used the Bestline product. GoofOff is way down my list. For old, as in 60's/70's vulkem, I like some judicioius heat with a real heat gun and your scraper of choice. My overall arsenal has dozens of tools and products and trial and error and experience go a long ways towards a time effective result.
Happy scraping... Mark D