Nut & Spring Washer or Nyloc Nut?

[Andy 308GTB]

In the quest to replace a pair of exhaust manifolds, I have emptied a considerable amount of my engine bay.
Much of stuff coming out hasn't been touched in 35 years, so the nuts and spring washers coming out are the original fixings.

Since I am working on a car, not a historic artifact, is there any technical reason why I cannot replace these with Nyloc Nuts (and where necessary plain washers). I guess that Nyloc Nuts can't be used where stuff gets really hot (i.e. joining exhaust manifold to exhaust box etc.)

[Andy 308GTB]

one eyed mick said:

Source your local fastener supplier and call with cash ! what you need go under many different names , stiff nuts ,hoddy nuts etc ask them for what they are known as locally . Nylocs will prob melt ,old school is brass nuts and spring washers !!

Sure, where stuff gets very hot I won't use Nylocs.
But on general bits and pieces, there is no reason to persist with Nuts and Spring Washers?

Hoddy Nuts - did you make that up?

[Andy 308GTB]

Thanks all, so there are plenty of nut/bolt combinations for joining the exhaust manifolds to the exhaust box.

But... is there any reason why nuts & spring washers should not be replaced with Nylocs in areas that are not subjected to significant amounts of heat?

[Andy 308GTB]

dudleybloke said:

What size do you need?

M6, M8, M10 and M12