My 2000 Montana's transmission failed, so we rebuilt it, & while the engine was out, we replaced everything likely to have issues. One of those issues is the infamous 3.4 intake manifold gasket which is prone to leaking coolant into the crankcase. The gaskets were soft & spongy at the coolant passage, getting ready to leak. These gaskets had been replaced 3.75 years & 30,000 miles ago. Used nothing but the factory recommended Dexcool 60/40 ratio.
I went to buy coolant, now everything on the shelf is "long life, use with any color coolant". I wanted the old style green coolant, but got the Prestone any color coolant which happens to be a green-yellowish color. Good thing, because there was Dexcool left in the engine, we only emptied the radiator (which we replaced) & rear heater core.
I watched the video by Flat Rate Master saying Dexcool is not bad, but GM put it in cars that had old style gaskets, & the acid in dexcool ate them up. Is the acid what's softening up my intake gaskets? These gaskets are supposedly the updated steel backed version, but they were still soft. I also read on here that Dexcool was reformulated a few years back, did that solve the issues? Flat Rate says the acid in Dexcool is what keeps the cooling system clean, & Dexcool does not mix well with air. My expansion reservoir is open to the atmosphere, so it's getting air.
Any thoughts? I'll post a link to the video mentioned.