It might be because it got wet. Mine have been like that after I wash the car or if it's in the rain for a while. It got so bad, I was ready to replace it but when the weather cleared up, it started getting back to normal. Ebay has plenty of them if you need a new one.
4L60E
The 99 Buick Century 231 engine will fit into a 96 Chevy lumina with a little fabrication.
Yes.
21 mpg
Your 99 Buick should not take off at all. However if the acceleration is slow it may be in need of a service.
A 2WD 4L60E from 96 will work for a 94 application, yes.
Behind the gas tank.
beneath the alternator
i believe so because they are the same body style
no im sorry i dont believe so...
1991-96 Buick Roadmaster, 1991-96 Chevy Caprice/Impala SS, possibly 1993-96 Cadillac Fleetwood
The overflow resavour is where you add coolant