Looks like that Dallas BBSRAM was made in 12th week of 1989. They (conservatively) rate them at 10 year life so it probably has some mileage. Hard to say when the "freshness" seal was broken (after first use the battery is connected) and what kind of shelf life they have though.

If you really want the RAM contents and have a equipment that supports it you can even read back the dallas chip and the write the same data into a the NVRAM. I can read/write to the FM16W08 with a GQ-4X profile set to DS1225Y.

I would probably just swap it out for a 6116 NVRAM unless you want to see how long the dallas BBSRAM lasts. Can't see but probably already have an IC socket installed.