Having to add about a gallon of antifreeze every 3 weeks or so , can smell antifreeze at exhaust , so thinking it is head gaskets (03 sle 240k miles ) considering the amount of miles and it costing about 500 in parts to fix myself thinking of just buying a motor with less miles, a while back I found a website that had 40 or 50 3.8 pontiac motors with around 110 to 140 k miles for all around 500 bucks each now can't find web site .

Does anyone know where I can find suck a motor ? or know anyone who has a wrecked 02-05 Bonneville with good motor I could just buy whole car also need new stereo lights gone out in mine , thanks

How long period of time have you been adding antifreeze? Months?
(alarm bells should go going off) water /oil bubbles on dipstick?
Possibly check with your local wreckers re the motor. You could also run a wanted add in auto parts craigslist etc. I am sure others may chime in with other ideas.
Sorry I have to add my 2 cents worth for others reading this.
If you notice a loss of antifreeze/coolant (alarm bells time) address immediately where the loss is coming from! Perform a rad pressure test & engine compression test if gaskets are suspect folks, before a new engine or complete rebuild is needed.
"Fact" oil and antifreeze do not mix well, will congeal & coat the entire engine'* interior very quickly even from a minor interior leak. This will lead to one heck of a mess in there & eventually complete engine failure.
I have a black mark on my overflow reservoir when cold. If it is down I am quickly aware of it.

Are we sure this isn't the typical UIM/LIM failure?

Actual Head Gasket failures are VERY rare. When the motors go, they usually spin bearings, or break something in the valve train.

Also make sure there is not coolant in your oil, the engine may not be as far gone as you think, but failure to take action now may kill it.

no water in oil no oil in water , been adding a gallon of water like every 3 months now a gallon every 3 weeks< service engine soon light is on but its saying car is running below engine temp , replace thermostat but its running 195-200 degree turned light off week later came back on but water lvl is fine

also when I remove engine cover there is a small amount of coolant on the intake next to front head and I can see a gasket (intake gasket) ? behind water pump it seems to be a little wet with oil but not to bad , I change oil at 20 % and usually get about 8 to 10 k miles on oil change usually have to add 1 to 2 qt oil between changes

im interested in this UIM/LIM failure , can you explain further ? is this the EGR gasket ?

There are the directions for the repair.

https://www.gmforum.com/mechanical-1...2/#post1506919

The general idea is that the plastic around the egr pipe degrades, and the coolant passage in the UIM becomes compromised, and starts leaking coolant directly in to the intake, and you start burning coolant. Yours seems to be turning catastrophic. It will only get worse until the engine takes on enough coolant to hydrolock. With this, coolant can also leak down in to the lifter valley, under the LIM, and get in to the oil. This guarantees you will need another engine if not caught in time.

With that many miles, you may as well do the LIM gaskets (probably due at this point also), because those, when they fail, guarantee coolant gets dumped straight in to the crankcase. That is very bad for business.

Thanks for the help I think ill try this first

This also highlights what the LIM gaskets look like when they fail

https://www.gmforum.com/specificatio...h-fact-288248/

But don't just take my word for it, have a look for yourself

I may have been around these parts for a while, but I can still be wrong