Sorry to necro, but for anybody who might still come across this thread, which they will because I did while looking for something else, I feel like it's important to correct misinformation even though I realize none of it was given intentionally.
The bottom line is, none of the answers is actually correct in this thread for about 95%, maybe more, of applications. The reason being, about 95% of manufacturers use PLACE BOLTS, which you can read about at the following link and I guarantee none of you ever heard of them otherwise they'd have been mentioned in this thread, on critical fastener locations like flywheel bolts, oil pump bolts, camshaft retainer bolts, etc.
https://www.earnestmachine.com/sites/default/files/products/imported/BHP.pdfYou will be able to identify Place Bolts by the undercut in the bottom of the head and the six cut out lines in the top of the bolt head. This design allows the bolt to create far more clamping power than a standard bolt, even when using a lock washer.
If you remove a place bolt on any application that is the ONLY kind of bolt that should go back in that application location. Generally these are used on applications where the bolt is not particularly long, since longer bolt bodies are able to provide their own additional clamping spring tension, and where they are both difficult to get to if a bolt were to come loose AND would be likely to create a catastrophic end result if they did.
Did not intend to step on anybody's toes, but sometimes, like I did, you might go half your career AFTER professional schooling, and have never heard of them, until somebody slapped me upside the head with that information. Hopefully, some of you here or others who come along later, will be better informed for the info. Good luck.
