They was thinking grade 2 bolts which wouldn't torque to spec without breaking. I rather replace a rusty head bolt then risk breaking off with torquingA tightened bolt behaves a little bit like a spring. A higher grade bolt at the same torque is going to be less springy. This is probably where their concern comes from. I suspect though that a head gasket has enough springiness that the grade of the bolt is probably irrelevant.
You are wasting money on bolts though.....
I always read for Kohlers to use Grade 8 but I think I used grade 5 on my last oneWhat are you torquing them 2 and what size?
Grade 2 half inch is like 40lbs. Grade 8 is like 80lbs
Probably are grade 5 but for some reason a few sites recommend grade 8sI think Kohler headbolts are Grade 5. I have 2 on the bench, (1 ea K321, 341) with what I think are their original head bolts, I'll look after work.
Your not going to hurt anything by using grade 8 bolts.Probably are grade 5 but for some reason a few sites recommend grade 8s