Don't. Add no oil additives to your engine. If oil additives were really that good, the oil companys would put them in their own oil.
You don't. Add not additives to your oil. If additives worked the manufactures would add them to the oil and recommend you also do so.
MORE Details needed also it depends on a couple things like who makes it & sells it.
Lucas also makes a synthetic engine oil additive.. Answer. Yes.
I do it. I use Mobile 1 fully synthetic oil and substitute a quart with the lucas oil. Been doing it for about 2 years and my cars still running like a champ, 01 Grand am. Got it with 35k miles and...