Hey Guys,

Just installed the replacement ZD30DI cylinder head over the weekend, followed the Nissan workshop manual to a tee.
But with one exception being, i used ARP ultra torque lube on the new OEM head bolts rather than just engine oil.

On a couple of the bolts on the last 90 degree pass there was a section where it felt like the bolt lost tension or got "easier" to turn, but then got harder again towards the end of the pass.

What i am trying to work out is whether ARP lube will give incorrect torque wrench readings compared to engine oil? & have i possibly over torqued the head bolts causing them to stretch past their yield point? (meaning there stuffed & need to be replaced)

Also if i do end up needing to replace the head bolts, is it possible to reuse the head gasket or will this need to be replaced?


Have done a bit of research into it & getting some conflicting info:

"Nonetheless, should the yield point of a bolt be exceeded, the technician will feel a pronounced “softening” of the load, almost as if the threads have been stripped off the bolt. At this point, the bolt is over stretched (if it does not break first) and most, if not all of the clamping force supplied by that bolt is lost - (https://www.mechanic.com.au/news/tig...the-right-way1)


"Unlike ordinary head bolts, TTY head bolts are designed to deform – but do it in a controlled way. Like a standard head bolt, a TTY bolt will stretch and spring back up to its yield point. But once the yield point is passed, the bolt becomes permanently stretched and does not return to its original length. Because of this, TTY bolts should not be reused." - (https://www.enginebuildermag.com/200...head-bolt-use/)


Any help is much appreciated guys!