The amount of heat these bolts have to tolerate is huge,no way will they last forever its impossible, hot and cold,and then they crack and brake had to get mine replaced several times over the last 12 years.Do I still love my 93 skyline ? you bet I do bang for buck and if you look after them they are fantastic nothing better. :-) :-) :-) :-) :-) :-) :-) :-)