What is the best solvent for an oily tar like substance?

[gefrie]

I think it was an oil previously and it's dark, slightly sticky and drying out.

Acetone doesn't seem to work.

 

[adaviel]

I would have tried acetone, too. Or gasoline, just because I have some.
Maybe alcohol (methanol/ethanol).

Of course, water, the universal solvent, but I guess that's too obvious and won't work on oil, only things that look like tar like month-old jam.

You could try warming it up.

 

[MikeH]

Acetone is a polar solvent so it probably will not work.

Depending on what you have available, I would try naptha first. It is not as volatile as many other non polar solvents. Naptha is is found as Zippo lighter fuel and also as charcoal starter.

If you cannot get these, xylene or toluene available as a paint thinner should work. Mineral spirits is another paint thinner which would be non polar.

Hope this helps.

Mike.