I recently replaced the heads on my 2004 Silverado 1500. There was a bad casting on one head causing it to leak coolant into the oil. After 10,000 miles, there developed an oil leak between the head and block. The bolts that came with the new head were called "stretch" bolts I believe. I had never used this type before and not sure it I installed correctly. As a first step to resolving this, I'm thinking of replacing these with standard bolts and torquing to proper footage. Would this require draining and replacement of oil and coolant? I'm thinking not, but checking with those that know more than I.

 

Most engines in todays world use what's called "Plastic Region Bolts".
These bolts are torqued to a specific torque and then advanced to a higher specific torque and then tightened a specific number of degrees and then again another specific number of degrees. A bolts holding or squeezing power is always created by the bolt stretch. With the advent of Aluminum Alloy blocks and heads that constantly move in a sliding motion on the head as heat expansion takes place and cooling contraction takes place the gaskets are now entirely different. The bolt holding or clamping mechanism for these new materials requires a different approach with todays materials. The Plastic Region bolts are generally not reusable. New bolts each time the head is replaced just like new gaskets. The stuff we used to Glue the Gaskets down with will actually cause leaks by not allowing the Head to Expand and Contract Sliding over the Block. It's an entirely new world.