Can you use 10 year old unopened paint?

Can you use 10 year old unopened paint? Using 10 year old unopened paint is generally not recommended, as most paints have shelf life of 2 to 10 years unopened depending on type and storage. Latex water-based paint typically lasts up to 10 years unopened if stored in cool dry place, not frozen, but after 10 years it may have separated, thickened, or spoiled, with foul smell indicating bacterial growth. Oil-based paint can last up to 15 years unopened if sealed, but may have settled and skinned over. Even if unopened, 10 year old paint may have degraded binders, poor adhesion, uneven color, and not perform well. You can test by stirring thoroughly, if it mixes smooth, no lumps, no sour smell, and applies evenly on test area, it might be usable for non-critical touch-up, but for important job, new paint is better. Check for rust on can, bulging, or dried top layer. If paint has frozen at any point, it is ruined. Primer like KILZ also has about 2 year shelf life. So 10 year old unopened paint is past recommended life, may be usable if stored perfectly and looks good after stirring, but risk of poor results is high, better to dispose properly and buy fresh.