I have used Hoppes #9 for most of my life.
I do know that is not recommended for nickel finishes on firearms.
It will wick under the nickel coating and cause it to corrode and eventually flake off.
I have a few Scandium pieces and have used #9 on them with no apparent problems.
I have recently started using something called M-Pro-7.
It is great at carbon removal and is benign to all finishes and metals.
It has the Constancy of thick water but really does a good job on cleaning.