Engine Flush - What product to get

I am wary of engine flushes for high mileage engines unless I am 100% certain that the gaskets and seals are in tiptop condition. If you can, remove the pan from the engine and inspect it and the pick-up tube screen. Make your assessment from there whether there's gunk in the block that would require a flush.

For comparison, I just did a cam cover gasket job on my 2010 CTS (3.6L V6). I am at about 210k kms. The spark plug tube seals on those two cam covers had hardened over time and were allowing oil to leak into the spark plug tubes and causing a minor misfire issue - and probably allowing dust to be pulled into my block. I worried that the problem might result in a ruined catalytic converter so I did the gasket job. The inside of the block was quite clean but those tube seals were somewhat gunky. Removing that gunk would have undoubtedly resulted in more oil escaping into the spark plug tubes.

Would a flush's detergent reach that far and remove that gunk? Hard to say - but I do know that I would not have wanted that stuff circulating inside my block.

if you really want to do a flush...Seafoam products would be the best imo for diy