My brother has a '87T with close to 300K mile (original owner). It's his 2nd Z car. He has a 2004 Roadster also. The 87T has close to 300K miles. He just recently changed engines and converted to a 5-spd. Nothing wrong with the original engine and turbos's, but he thought it was time to take it out and built it up a little--still doesn't burn any oil. If you do the regular maintenance, the Z engines will last forever. I've owned 6 Z's since '74 and NEVER had a engine, transmission or rear end problem. A couple of them were very high mileage. I'd say they were very reliable.