Lock washers or no?
 

Ready to reattach my side pipes to the exhaust manifolds using that innovative invention, packing and sleeve ;)

As is so often the case, one of the brass nuts have fallen off the manifold stud. I put anti seize on these and they come off as they should but occasionally they seem to fall off on their own too. Do people typically use lock washers on these?

I've resigned myself to the fact that I’ll leave a trail of oil and ATF wherever I go. I’d rather not leave parts too.

I don't. But I don't use goop either.

:iagree: x2
extra-long nuts' brass helps prevent siezure.

Are you sure the steel studs' threads are thick & robust?

The threads on these are pretty rusty. They have been on there long enough that I don’t remember if I put them on or not. They don’t look to be missing any threads and require some effort to remove.

If all else fails, just use double nuts. Lock washers have their place, but in an application like this with the heat/cool cycles, they tend to loosen up. GM used crimp style locknuts for a reason.

Ok, you gentlemen have convinced me, no lock washers and no antiseize.

Prevailing torque nuts so they do not back off under heat cycles work well. They can be a chore to remove after many years and thousands of miles. If you don't drive your car daily for many years you should not care about that.

You might to consider purchasing, or fabricating, lock washers that you bend over to lock-in the nut (Tab Washers it seems they're called) and secure the nuts. If I had a problem like that is what I would consider. Not sure where you'd find them though. I do see some for sale for the top of exhaust manifolds and for half-shafts, but I would think they'd be available as individual locking "tab washers"....
Here is an image from mcmaster-carr.... prices are a bit silly for a washer and you can probably find at the local hardware store... or fabricate your own from a "fender washer" for a few pennies:

https://cimg3.ibsrv.net/gimg/www.cor...18cb744531.jpg