if engine is very old can try use it, why not. it's high viscosity will raise the engine oil viscosity a lil so thicker n heavier oil will leak slower n lesser at low rev low temp. observe white smokes from exhaust if it reduces. it doesn't justify to overhaul a very old engine unless u suddenly got loaded n plan to restore it

can try STP's high mileage engine treatment+stop leak. also try using 20w-50 by next oil change

tarik cow better than engine burnt out tarik tow truck

been using engine treatment for decades. if no improvements aint recommending. wanna top overhaul up to u