OK, the wife's '97 Buick with the 3.8 V6 is going to get a change to Prestone. Dex Cool was specified in the owner's manual and I have added a 50/50 mix of that when needed.
Wally, Dex cool is the least of the problems on that engine. If you have been adding coolant w/ no leak found they tend to melt the upper intake manifold around the ERG tube from the lower manifold (just behind the throttle body). ERG tube is too close to plastic, melts into coolant passages to throttle body & sucks coolant into intake.
#01-06-01-007C: Engine Coolant Consumption or Coolant Leak (Inspect for Material Degradation/Replace Intake Manifolds) - (Sep 20, 2007)
Subject: Engine Coolant Consumption or Coolant Leak (Inspect For Material Degradation/Replace Intake Manifolds)
Models: 1995-1997 Buick Riviera
1995-1999 Buick LeSabre, Park Avenue
1996-1999 Buick Regal
1998–1999 Chevrolet Lumina, Monte Carlo
1995-1996 Oldsmobile Ninety-Eight
1995-1999 Oldsmobile Eighty-Eight
1998–1999 Oldsmobile Intrigue
1995-1999 Pontiac Bonneville
1997-1999 Pontiac Grand Prix
with 3.8L Engine (VIN K — RPO L36)
also the lower intake gasket to heads is a plastic w/ rubber inserts. Coolant passages @ center of intake (not on ends like SBC) so may not see external coolant leak but leaking into crankcase. Newer gaskets have metal w/ rubber inserts, hold up better. great engines other those 2 items.
