On Wed, 16 Jan 2008 04:36:18 GMT, with neither quill nor qualm,
"toolman946 via CraftKB.com" u40139@uwe quickly quoth:

You guys may find this interesting.

A number of years ago a friend of mine was the Service Manager for a large
Caterpillar dealer. They began having fracture problems with grade 8 bolts
(or maybe grade 8 studs) on the diesel engine oil pans. They replaced
numerous oil pan bolts and they still kept breaking.

Ken (my buddy) while not being trained as an engineer was a pretty sharp guy.
He noted that the shop had begun to use automotive silicon in place of the
composite oil pan gasket. He thought that the silicon was allowing the oil
pan to "float" slightly causing a high frequency vibration that was inducing
stress fractures in the grade 8 bolts. He ordered the shop to resume using
the original gaskets and the problem never recurred!

His theory made sense to me. What do you think?

I think his other instruction (to torque the bolts instead of just
using the 1/2" impact driver until stalled) was the key. But that's
just me.

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Chaos, panic, and disorder--my work here is done.