Just got home with a new to me 5906. Its a police trade that is very dirty that i don't think was shot much Is it OK to clean the stainless with Hoppes # 9 & clean inside with break clean.
Be careful with brake cleaner - some can eat away at plastic parts (grips and the like).
Personally, I will not use brake cleaner anymore. It is a quick way to clean things, but a little too harsh in my opinion. I'd rather spend the time to detail strip it and clean it with good old fashioned elbow grease.
Unless you have experience with the 3rd Gen pistols, I would recommend field stripping and using a good spray cleaner, and work the parts 'till the spray comes out clean. I use M-Pro 7. Then go back and lube the parts.
The only reason I don't recommend a detail strip if you're inexperienced is that some parts are currently hard to find. I've seen people break the side plate and not be able to find one.