Handling bolt securing and how does it work best?

Moin, I’m just wondering, if I turn a screw (before oiled, 6mm) with a cloth grease free, and then into the thread with screw securing e.g. Loctide middle-strength, is the screw then secured? although the thread hole is oiled inside, can be? or if I make the screw (before oiled) fat free, clean with brake cleaner, and then wipe with cloth afterwards, then screw securing Loctide middle-resistant up, and in the thread hole also clean brake cleaner he (can I not wipe off) is the screw secured? I just changed the cooling water flange at my golf, which is sitting at the engine block, therefore the question, which I wanted to secure the screws. Sometimes you can not clean the threaded hole… Does screw securing also, when I have prepared brake cleaner, and then immediately turn the screw securing after, so the screw with screw securing. How do you see this??? Holds screw securing at the “nassage” brake Cleansing?