I am getting mixed messages when it comes to using grease on TTY bolts. I have read a few articles and am finding that they vary on whether or not to use a lubricant on the bolts. Here are a couple examples:
A Yes vote:
As with conventional head bolts a good thread and under bolt head lubricant is still
important. Lubricants reduce the amount of friction between the fastener and the surface it
contacts while being tightened. A quality thread lubricant will convert more of the torque to
more usable clamping force instead of having it lost to friction.
A No vote:
TTY bolts are generally installed dry. Tend not to apply any oil, grease, assembly lube or sealer around the bolt threads. The main reason why is due to the fact lubricants lessen friction every time a bolt is tightened. This truly increases the torque load around the bolt, which may overload and stretch a TTY bolt too far, leading to it to break.
So which is it? My last engine I used it on both the head and threads, seemed to work fine.