Quick answer
You should use them if your engine shows mild issues—like small leaks, noise, or sludge. If it’s healthy, or severely damaged, additives may offer limited value. Assess your needs before deciding.
Detailed answer
Modern oils handle normal conditions well, so an additive is most beneficial when specific minor problems arise. Older engines with loosening seals can benefit from a reconditioning formula. A performance engine under heavy stress might thrive on friction modifiers. However, if everything’s fine, you might just waste money or risk altering the oil’s chemistry. Always weigh the cost and potential gains. Where there’s a legitimate issue, additives can be a cost-effective stopgap or improvement.
