Only a few engines use these but I guess its another form of anti-vibration device vs spring washers etc . Considering the only choice on imperial threaded engine parts / headers needs small head . The choices are ARP or Mr Gasket serrated. Serrated is common on Jap car .

Anyone using Serrated Mr GASKET fasteners on there imperial threaded motor etc ie chevy ??? Experiences??
[""Cheap"" fasteners are often that and they don`t work as designed]

Where u need an absolute lock washer try NORD Lok , I use these on my caliper bolts because of turned down the head of the allen cap screw,, to clear the braided brake line . A split/ spring washer spreads and not enough grip with the turned down head.