Re: Threaded rod? Bolts?studs?
8.8 is standard ISO grade for industry and plenty strong for these engines. 10.9 may be a little brittle for exhaust and motor mounts but fine for head studs. Studs are kinder to aluminum threads than bolts. Twisting a bolt under load into aluminum is very hard on the aluminum threads and will strip them quite quickly. Most hardware store threaded rod and bulk bolts are lower grade, so read the grade. Metric should be 8.8