[jonKranked]

I have an old bottle of dot 5.1, at least 3-4 years old, but still factory sealed and unopened. Still usable?

 

[rideit]

You should taste it first to see if it’s skunked.

 

[6thElement]

I have an old bottle of dot 5.1, at least 3-4 years old, but still factory sealed and unopened. Still usable?

Still fine.

 

[Sandwich]

I think you're fine as long as it's sealed.