1998 Chevy Tahoe coolant in oil

Just checking the dipstick for oil is not acceptable in my opinion. Yes the oil should have been changed, but the amount of coolant that could potentially get into the engine after this repair is not enough to seize it after 50 miles. My guess is that the intake manifold gaskets were installed incorrectly. There is a strict torqueing proceedure that must be followed to a tee. If not, the gasket can very easily crack -- internally, without notice -- and allow large amounts of coolant to flow into the oil when the engine gets up to temperature. Sounds like this happened to you. There is no doubt that the mechanic is responsible for this. He or she overtightened the lower intake manifold causing the gasket to crack and fail. I would contact a lawyer asap!

I dont think that was the case because now days alot of intake gaskets habe metal spacers (at least GM does) to prevent over torqueing. I would say for sure not having the oil changed was the reason the engine failed. Anytime an engine has something takin apart that exposes the internal parts, an oil change in my opinion should be done.

Well rhall77, thats if you use GM parts. The fel-pro (cheaper) lower intake gasket does not have the metal spacer update and is commonly sold at any autoparts store. Even with this spacer it most certainly is possible to crack this gasket upon installation. Consider this -- what if the lower intake manifold was warped? Was it checked for warpage? This is an all too common - over looked - problem. Also, in my opinion, even if the oil WAS changed - after replacing the gasket - the gasket was cracked. When the engine got up to temperature "50 miles down the road", this crack opened up and dex-cool destroyed this engine.
Rhall77, I am sure you have changed many of these gaskets ( as I am sure the so called mechanic in this case has). If not then here is a little tip -- the first thing you do is drain the coolant. The little bit of coolant that still may be left inside of the intake WILL NOT cause a Chevy 350 cubic inch engine to SIEZE UP just 50 miles down the road. I am willing to bet if you poured 1/2 of a gallon of 50/50 dex-cool directly into the crank case of a chevy 350 there would be no problem. The problem here was the constant flow and mixing of coolant in the oil !

Trust me I have worked in a dealer for many years. I have seen where people have not changed the oil but did drain the cooling system and the engine did fail. Usually a intake if it was warped (never seen one but may be possible) would also leak externally. I think and you maybe be right also for a constant flow, that it could be the gaskets (i never use after market gaskets), but it could also be corrision not sealing on the water ports. But I think in this case the oil not being changed did cause the problem. Any contaimination of antifreeze in an engine (even the slightest amount) will destroy bearings in no time. TRUST ME. Either which way we both look at it we are gonna have our own opinions. But at least we both know that antifreeze contamination was the main problem and yes contact your lawyer ASAP.