The rubber parts to be softened have to be removed from the vehicle so that they can be soaked in the solution for up to 24 hours. I've used this method on carb boots, intake hoses, etc. on the different motorcycles I've had over the years. A lot of them were 20 plus years old so finding parts is difficult and this was the best method of restoring those rubber pieces as you can't fine NOS often times.Whats the mix ratio of oil to alcohol, and what proof do you use?
Oil of Wintergreen (methyl salicylate) (I bought it on Amazon, you can't usually find it in stores)
Rubbing Alcohol (90%)- 3 times as much as the oil
Plastic or glass container to hold the parts (I've used ziploc bags before in another container as well, because everything it touches will smell like mint, so glass containers are good)
Cover for container (Wintergreen Oil is like very minty smelling and the alcohol will evaporate otherwise)
Pour enough oil and alcohol into the container as needed to cover the parts - one part oil to 3 parts alcohol.
Place clean parts in. Make sure that they are covered so all parts of the rubber gets treated.
Cover with the lid to contain the peppermint smell and prevent the alcohol from evaporating.
Check periodically to see how soft the parts have become - remove them once they are soft enough. Leaving them longer will not make them softer, but I've seen people do several days anyway.
Wipe dry with paper towel or rag.
The alcohol is used to carry the oil into the rubber and is then evaporated away once the parts are out of the solution.