Quick answer
They can if misused—like adding too much or choosing an incompatible formula. Over-thickening, foaming, or deposit formation can result. But used correctly, they’re typically harmless and often beneficial.
Detailed answer
Common pitfalls include combining multiple additives that clash chemically, using a product high in metals that foul emission components, or pouring in double the recommended dose out of impatience. These scenarios can cause your oil to foam, lose proper viscosity, or create sensor blockages. But with a straightforward approach—one additive at a time, following the label, ensuring it’s right for your vehicle—risk is minimal and improvements are possible, especially if you have mild engine woes.
