One problem related to brake fluid leak has been reported for the 1998 Buick Lesabre. The most recently reported issues are listed below.
Brakes went out, had no pedal at all. Managed to get home. Fluid full. Master cylinder ok. Brake shoes new. Brake fluid not leaking. Oil is leaking, but no brake fluid at all. Cannot find what the problem. Cannot get any pedal on the brakes.