Do 'no smoke' treatments actually work?

Can you advise me on Wynns Stop Smoke oil treatment or similar products. Do they actually work? I have a diesel and have been told it needs either a new fuel-pump or injectors will cost a lot more than the cars worth. I know a treatment won't fix it but could stop the smoke.

Asked on 1 October 2018 by John Cheetham

Answered by Honest John
Usually 'no smoke' type treatments are effectively oil thickeners to help compensate for failing piston rings or valve stem seals. Smoke from a diesel is often because the injectors have failed. It's safe to try an injector cleaner in case the problem is dirty injectors, but all it can do is clean the injectors up a bit.
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