I had a plenum issue on the first of two LeSares. It was the smell of fuel of and the prospect of a fire that I had it replaced. The second car had a plastic connector on the fuel line issue that was a problem and remained so after it was replaced until I put on my own connector. The 3.8L is great on highway mileage for a big car. I'm more than convinced premium fuel for highway driving is the way to go, but nothing helps your mileage while driving around town. The coolant and plastic plenum problems may have been fixed on the 2000s. I loved the 3.8L and feel you may not do better with a different one for the car you get in a LeSabre, its worth the fix.I voted!! I had a 1989 LeSabre that I sold with over 225000 miles on it. I still own three LeSabre's. My 1993 has 180000+ miles on it, my 1998 has 160000+ and my 1999 has 82000 on it. In my opinion the older the LeSabre the better they were. My 1989 and my 1993 never had any repairs other than a starter or an alternator. My 1998 had the plenum coolant leak problem where the cylinders fill with coolant, an $800. repair for me. My 1999 has had a power window problem and is loosing some coolant and I am afriad an intake plenum repair is coming soon. I'm not sure what is the cause of these intake plenum leaks, but you can find reference to 100's of cases on the internet. It may be the dex cool coolant they switched to or maybe just that they use a plastic part for an intake plenum. Whatever the cause it is souring me and many others on Buick's and the 3.8L engine.