Q&A

Belts have some advantages, and historically have been better to use in the place of chains because of the quality of the motor oil lubricants available to manufacturers. Chains are higher friction.

Now that synthetic oils are becoming more and more commonplace, manufacturers are taking advantage of their qualities and using chains.

There are a myriad of other technical reasons that I hope others can offer.

If your Mustang was an earlier year, it most likely did not have an over head cam or cams. If you have a push rod engine, the cam and the crankshaft are connect by timing gears and a very small chain, which last a long time. When over head cams became much more common, it was easier and cheaper to outfit them with a belt. Timing chains on over head cam engines still need replacing and Matt is correct that syntheitc oils have helped the wear life of an over cam engine timing chain. However, on a Mercedes V8 a timing chain job is around $3500 -$4500 and it can be needed at around 100,000 miles. Still mad about that belt?