I think the head gasket in a bottle goes into the engine oil, not the coolant!

 

The blue stuff and others goes into coolant. It is silica, small chance to plug heater cores like the old fashioned, organic stuff (which is installed at the GM factory). The old fiber stuff can clog things up if over used. The stuff that was in anti-freeze could do it, but after the lawsuit it is not used. The metallic ones can be over used.
Overheated DexCool forms clumps that I soppose could clog things.

 

So, just a bottle for coolant leaks at the head gasket, nothing for compression leaks between cylinders, or oil leaks.

 

It claims to go anywhere the coolant might be escaping and seal the hole. If you are not losing coolant it won't help anything. Oil additives just swell the rubber seals and maybe thicken the oil up enough to help the oil control rings. Some oil additives claim to coat the cylinder walls to decrease friction.

I have experienced a significant increase in MPG when my Toyota dealer threw some BG MOA in an oil change for free. Only lasted a few tanks, I don't think it would pay for itself (gas was cheap then).

None I know of claim to seal a "dry" leak. Maybe carbon deposits would eventually catch up to the burning.

 

So, if’s it’s a compression leak between two cylinders, time to bust out the tools and change the head gasket!
seeing as you’re in there might want to consider changing the timing chain, guides and tensioner, balance shaft chain and guides and tensioner, new head bolts for sure. Perhaps a thermostat and water pump along with fresh Dexcool 50/50 mix.
There are four bolts inside the timing chain end of the cylinder head, They use a “e12” 6 sided Torx socket. Torque all 4 bolts to 22 ft/lbs

 

Don't forget the upgrade timing chain guide bolt!

 

Or that discount code!