Originally Posted by
John E
That may be true, but of greater concern is that elongated chain will definitely wear out the cogs and chainrings prematurely.
It's absolutely critical to replace the chain before it stretches significantly if you want the rear sprockets and chainrings to last and work properly. These older model chainrings and sprockets are often very hard to find. Also, frequent cleaning and re-lubing of the chain will help a lot. I have a 6-speed Shimano freehub uniglide casette that is over 30 years old and still going strong.