Torque specs from the manual vs what the old hand says, which one do you trust?

Been at a shop in Tulsa for 4 years now and every time I torque a head bolt to factory spec, the older guys laugh and say I'm gonna blow a gasket. They swear by going 20 ft-lbs over what the book says on anything pre-2000. But I've pulled apart engines that were overtorqued and seen stretched bolts snap clean off. On the other hand, I had a 6.0 Powerstroke leave the bay with properly torqued studs and it came back with a nasty coolant leak. Is the manual really that spotty for older diesel blocks, or is this just stubborn tradition? Who here has actually seen a failure from following the book exactly, and how many miles did it take?

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the_logan5d ago

The manual is a starting point, not the whole story, and that 6.0 coming back on you is proof the book doesn't always know the real world. I've seen more failures from guys guessing with a breaker bar than from following specs, so I'll take the torque wrench over tradition every time.