Loctite screwlock nutlock studlock threadlock and retainer adhesives loctite 243 loctite 243 is a medium strength general purpose thread locker it secures and seal bolts nuts and studs to prevent them from loosening due to vibration loctite 243 works on all metals including passive substrates such as stainless steel aluminium and plated surfaces it is proven to be tolerant of minor contamination like industrial oils engine oils corrosion prevention oils and cutting fluids loctite