Bonneville (90) losing power steering fluid

I'm losing about a half pint a week, and since the pump is clean as well as the lines, i'm assuming there is a seal gone in the steering box. Does anyone know of an aftermarket additive that will swell the seals and eliminate the loss of fluid, or reduce it? Removing the steering box to replace the seals is a big, expensive job. 'Preciate any info. Thanx.

Try Lucas power steering additive.

Thanx for the info GDPDad. I tryed this stuff @ $12Can/bottle. Man is it thick. The 'structions said use the whole bottle and maybe a 2nd one to seal the seals. lol I could only get a 1/2 bottle in and it lasted about 10 days before the squealin returned, so I used the balance to top up the reservoir & we'll see how long this lasts. Maybe it acts differently in cold weather, although the bottle says "guaranteed to stop leaks". And the saga continues. Thanx again