name withheld by request


whoever you talked to at the dealer doesn't know what he is talking about.

Frequent coolant changes are ESPECIALLY important in the 93 due to the all aluminum construction of the Northstar engine and particularily because of the aluminum heads. The conventional , green, coolant that was used in the 93 Northstar uses silicates to provide corrosion protection for the aluminum parts. The silicates deplete over time as they are sacrificial by the nature of the protection mechanism. After 2-3 years/24K miles the silicates are depleted to a low enough level that they are in insufficient concentration to adequately protect the engine. When an aluminum cylinder head starts ot corrode it generall cracks in that area as the corrosion site creates a stress riser. In addition, the corrosion inhibitor depleted coolant allows the steel substraight of the gaskets (most notably the head gaskets) to start to corrode from the edges where the gasket contacts the coolant. Eventual head gasket failure is the result.

I think that lack of cooling system maintainence is one of the main reasons for long term engine problems with
the Northstar engine.

They are sadly misinformed. If you read the maintenance requirements the coolant change intervals are very specific.

Some people don't think that the aluminum engines need the frequent coolant changes because the coolant always stays nice and green and it checks good with a tester every year (for freeze protection). It's true the ethylene-glycol is still good but the corrosion inhibitors cannot easily be tested in the field and that is what has failed. The coolant stays green because of the nature of the corrosion of aluminum.....cast iron engines turn the coolant red with rust when the coolant has failed and it is obvious it is time to change. In addition, the aluminum engines but a much greater stress on the corrosion inhibitor package.

The coolant supplement pellets are still recommended for the Northstar. They are absolutely mandatory for the 4.x engines because an internal coolant leak can go undetected and contaminate the oil and cause engine failure. The sealer in the Northstar maintains the integrity of the cooling system but the Northstar is designed such that it is virtually impossible for an internal coolant leak to contaminate the oil....so the sealer isn't a "life or death" issue just an insurance policy against any leaks or seeps due to casting porosity or a gasket surface mismatch or something.

Maybe your dealer is confusing the 93 Allante with the 1996 Cadillac Northstars that were factory filled with the DexCool coolant that is ,indeed, a lifetime coolant and does not need to be changed frequently.

Allante's are no different than any vehicle with brake fluid. Brake fluid absorbs water by nature and over time can ac***ulate significant amounts....enough to cause corrosion and brake problems. Frequent bleeding and purging of the brake system with fresh fluid is a good practice in any vehicle....especially one with the sophistication of the Allante brake system....i.e...expensive to fix...