I have about 184K on my '94 Eldorado and it still idles and runs like new. My advice would be to have the car checked out by a reputable mechanic before you look to make a deal. When I bought my Eldo I later found out that the transaxle torque converter was slipping. After finding out about the on-board computer diagnostics I check for codes and I indeed saw the torque converter, P039 trouble code along with ride control codes. The dealer guaranteed the car and agreed to pay half the repair bill. Instead, I said drop the price by $2,400 and I'll still buy it. Well, the torque converter does need to be repaired but, from what I understand, the car will keep running.
It's difficult to gauge a used car by what others have experienced. Some will experience problems needing major repairs and some will not. You may be able to check for trouble codes by using the on-board computer. If its OBD II equipped then you will need a code reader. OBD II was introduced in 1996, but it may be worth a shot to see if the '96 SLS has the OBD I.
If it's OBD I equipped then you can check for codes as follows:
To enter diagnostic mode:
1. Turn ignition "ON."
2. Depress the "OFF" and "WARMER" buttons on the Climate Control Center (CCC) simultaneously and hold until the segment check appears on the Instrument Panel Cluster (IPC).
To get out of the diagnostic mode anytime during the test, depress the "AUTO" or "DEFOG" button, or turn the ignition switch "OFF." Trouble codes are not erased if this is done prior to selecting "CODES CLEARED."
