Exup valve

[Gaz66]

Mine's exactly same, don't worry about it, avoid cheapo copper grease, it's not up to the job , buy proper high temp copper slip.
This stuffs not bad for money.

https://www.zoro.co.uk/shop/lubricants-a...C%2BLubric

or you can pay a lot more for higher grade stuff.
https://uk.rs-online.com/web/p/lubricant..._Whoop+(2)

:thumbup