Sorry, but clearly some people posting here have no clue how TTY bolts work, based on the posts above.
The clamping force is designed to require a specific tension in the bolt. The way you get that is to use the threads as a micrometer - once the head of the bolt has contacted the clamping surface and you've taken out the slop in the joint, turning the bolt a specific angle causes the threads to stretch the shank of the bolt by a very specific amount. This is what provides the correct clamping force - it's exactly the same concept as using a stretch gauge on rod bolts. The lube on the threads ensures that you have taken out the slop in the joint BEFORE turning the fixed angle to provide the stretch and preload. If you didn't lube the bolts, you didn't take out all that slop and thus you did NOT get the correct stretch in the bolt when you applied the fixed angle. This is NOT a properly clamped joint and the head gaskets will likely leak at some point.
The whole point I was trying to make in my first post (which was apparently lost on people) is that the good news is that the friction in the threads means that you likely did not stretch the bolts past yield the first time, which means that you could probably remove them, lube them properly, and retorque correctly without having to buy new bolts. Doing nothing is a big mistake.
Thank you for saving me the keystrokes. TTY doesn't mean they're a one-time-use, it simply means the way you achieve the proper bolt stretch uses angles, not torque.
As you torque a traditional head bolt, the friction on the threads (lubed or not) becomes exponentially greater. The torque spec is a ballpark at best and assumes perfect threads, same coefficient of friction... etc. It's not very accurate to use torque as an indicator of bolt stretch and therefore tension.
If you instead use a lower torque value (before you get too deep into that exponential friction increase) and then use the angle method, you have used the ramp rate of the threads to provide a calculatable and far more accurate amount of tension than if you just torqued them to 80.
But the bolts themselves aren't made out of some special, one-time-use magical steel. They are still properly tensioned at the correct
bolt stretch, regardless of the actual rotational torque. This is why I really hate the term "torque to yield" because it implies that you are torquing them to the absolute limit. It's basically saying "torqueing until they give up."