Engine Coolant Type and Change Interval
All 1993-1994 Cadillac Northstar Engines used standard green, low silicate engine coolant. Starting in 1995 GM introduced "DexCool" coolant and all Northstars from this point forward came with this from the assembly plant. Change interval was 5 years or 100,000 miles. At Northstar Performance we recommend the following: Flush your cooling system, and use standard green, low silicate universal engine coolant. Commonly referred to as its chemical formulation: Ethylene glycol. Most of the time this is dyed green. The reason I recommend this is because I have seen the OEM formulation of DexCool cause rust in the head gasket cores- to the point where the head gasket itself will fail as the core corrodes away. I have also seen this formulation grow a type of mold that can clog coolant passages, and it becomes so acidic it eats aluminum. Now I am not a chemist. But I have torn down more than 700 Northstars and I see the results. I don't care what argument anyone puts forth to me, an end result is an end result. The early Northstars I've torn down that used standard green coolant from the factory, never had the cores rusted or had any aluminum damage or growing deposits.
Use green, universal antifreeze and be sure to dilute it only up to 50% with distilled water (not tap water).
