A little story; engine but not Fiat related.
I once owned a Mazda 2.0 litre , an auction bargain bucket but it went OK apart from using a bit of oil. Basically first start of the morning was positively embarrasing my car engulfed in a huge cloud of smoke. I tried quite a few of these 'bung up the holes and gaps' potions but non seemed to work, in fact often making matters worse.
As a last ditched attempt at curing the smoke problem, but without stripping the head down, i tried a product called
Forte -Seal conditioner (hyperlink). It is quite expensive at about £10 but i coudn't believe how effective it was. I'm pretty sure that my problems was caused by old, hardened, valve stem oil seals (130K+ ) This stuff reacts with the seals chemically and re-impregnates the plastisciser properties, effectively making the seal more pliable. With age and heat seals can become hard and brittle. So unlike some other products that effectively make your oil thicker, or just bung holes up this stuff actually re-conditions the existing seals themselves.
It definately worked for me on an old dog of a car, however as always,
your money-your choice. It might just be quicker and cheaper to isolate which seal is leaking and replace it. For me though If i get leaky seal problems again i will try this stuff again ( in conjunction with an oil change)
Good luck , hope you solve your problem cheaply and quickly....