After breaking a bolt on my oil pickup tube yesterday, I decided that today I would check out the two bolts on my front cover that woulnd't torque down...they would just spin with good resistance. What I found was frightening. The bolts had stretched A LOT. The 35mm bolt had turned into about a 39mm bolt. The part of the threads that stretched were about 3mm and the original pitch was 1mm. Imagine this picture x2-3 to get an idea of what I was looking at.

The scary part is, I was using a torque wrench, and the torque setting was correct at 15 ft-lbs. The wrenches were fairly new Snap-on. Talk about a WEAK bolt. Needless to say I'm replacing ALL the old bolts now.