Then i would recommend a good bleed. Get a bottle of Sea Star Fluid and the hose to screw in the helm. Turn fullright while someone opens the left bleed valve. Keep turning until there is no air. Close that valve, turn wheel full left and open the right valve until no air.
ATF is a solvent base and that's why it affects the seals. A FWB dealer, no longer in business, would use ATF in steering systems and Trim systems in every boat they rigged. Then when the customer had trouble they said seals were not covered under the warranty.
My Sea Star Steering (Sailfish boat)had the same problem. The mechanic bleed the lines and filled it with fluid several times. Ultimately the helm had to be replaced. Fortunately, Sea Star did not charge for the helm. It has worked extremely well since. On the Sailfish Boat forum, this sound like a fairly common problem.
Don't know if this will help or is good for your problem (system)whatsoever. I had a problem (very stiff spot while turning) with a rack and pinion steering in a Chevy. I bought a small bottle of LUCAS Power Steering conditioner. After adding to the system it corrected the problem in less then 1 mile. If the system can't be fixed by bleeding and has to be replaced you can't go wrong using it as it's guaranteed or your money back. Cost about $8.00 and save receipt if you want to go through contacting them if needed.
As far as their oil additive I don't use it. After being used in a mechanic friends truck he had to get into his engine. The Lucas is so thick and pooled in the bottom of the oil pan and never completely mixed. Maybe it just gets that way when cool, we didn't know.
I buy mine from a local Mom and Pop auto parts store but Wal-Mart in fact carries it:banghead:banghead:banghead Wal Mart SUCKS