Hi Guys. Probably not the right forum for this but here goes.

Question 1:

It would seem that the dexcool and my Mobil 1 have decided to move in with each other (oil pan). Is this a common problem with these engines and if so is it just a head gasket or are these iron blocks prone to cracking?

Question 2:

Either way, with close to 300K on the engine, just replacing the head gaskets would appear to be a bandaid solution. The engine is just tired and I need reliability. Have found a low mile replacement but it is the LQ4 version not the LQ9 (higher HP) that is in the truck. Both engines are identical except the LQ9 has flat top pistons and a performance tune. My question is, if I opt for the LQ4, would I need to necessarily change the tune? Can't see the computer knowing the difference but who knows.

Rest of the truck is fine, having replaced most of the consumable bits over the past two years so it would be a shame to scrap it, especially considering the cost of a new (newer) one.

Would appreciate some input.