Probably 10 years old, but unopened. STP brand. Still good to use, or should I toss it?

I already know this is probably a stupid question, so please don't tell me that it's a stupid question.

Thanks
Al

I wouldn't use anything with the name STP on, be it brand new or 10 yrs. old.

Their product line is at the bottom end of the snake oil spectrum.

Just my 2 cents.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"