It could be that way, Lee. I know that the trucks use a better intake gasket setup than the cars do....we all know the crappy gaskets that the later 3.1 and the 3.4 had. The L36 had the same issue with the poly-resin intake. It still seems kind of hit and miss really. Although my grand am didn't have the problem...but of course when the gaskets cracked on the intake and you couldn't get a set for about 8 MONTHS...I think I was putting a gallon....yes...a gallon of coolant in it every 4 days to keep it topped off...so in a sense it was like flushing the system every 2 weeks.
Bottom line, it's pretty much up to what is going on in the car, and preference. I put green into my car...simply because it's not $18 a gallon and it's not as hard to find just in case you have a mishap on the road or something.
And BTW...I'm not a mechanic, I sell parts to the mechanics in the shop. That's how I can keep on top of the service bulletins that come out on these things.
