Hi there. I am trying to get opinions on the best and safest Head Gasket Sealer that will be used on a 2003 ford focus. I was recently told by a mechanic that my head gasket needed to be replaced and was the cause of the water reservoir losing antifreeze and constantly needing to be added even though there were no traces of leakage.
I was quoted $800 for this repair but after researching online, I have heard about cheaper alternative fixes for those who cant currently afford the replacement.
I would like to know a professional or anyone with experience on using these Sealers, opinions and recommendation on which one to use. I have read quite a few positive reviews on Bars Leak 1111 head gasket sealer, but I have also read reviews and complaints of customers who used this product and experienced more problems such as blockage and and engine over heating.
Any recommendations would be appreciated. 
Here’s a link to a previous discussion on this same question.
http://community.cartalk.com/discussion/2276613/engine-block-sealant
Look closely at @tester’s recommendation on sodium silicate.
Hey Joemario, thanks a million!
The best sealer for a damaged head gasket is… Wait for it… A New Head Gasket … go figure.
Yeah, unless you’re really strapped for cash, and willing to junk the engine if this doesn’t work, I’d much rather spend the $800 and fix it.
Additives are best used in old beaters where there’s a desire to squeeze a few more months out of them at the risk of permanently disabling them, especially when the owner knows the vehicle is on its way to the boneyard anyway. Additives are almost never a true and permanent fix.
If you hope to keep the car for a long time, replacing the headgasket is the best option. $800 is not an unreasonable cost for this work, so if you consider the mechanic trustworthy I’d suggest “biting the bullet” and giving him the go-ahead. Where else are you going to find a good used car for $800?
Does the car run rough and blow white smoke when you first start it? If not, I would investigate the coolant loss again…First step, have the system pressure tested over a fairly long time period, 15 minutes to 1/2 hour…I would find the leak for certain before I started tearing the engine apart…
Fifteen minutes to half hour isn’t a long time. I’ve had to sometimes leave the pressure tester connected overnight before a leak revealed itself.
Tester
In a pinch you could try re-torqueing the head bolts I suppose. Never tried it myself, but I’ve heard this can be effective as a temporary fix sometimes.
The car does not run rough or blow white smoke at the moment. The mechanic who diagnosed it supposedly spotted antifreeze on the piston rods ( not familiar with the exact specifications of the engine ) but it was near the head gasket. He claims this was the reason for the antifreeze constantly going empty without any visible signs of leakage. It was said to be burning away as the engine ran.
Also, when driving the car, I sometimes hear what sounds like a bubbling sound coming from the water coolant tank. When I park and check the coolant tank, most of the antifreeze appears to be gone, but then minutes later, it slowly pours back into the cooler tank. I still find myself putting a little bit of antifreeze into the tank every few days or so.