Saab A/C leak -- might anti-leak refrigerant make a difference?

Our 98 Saab’s A/C seems to have a slow leak. Has anyone tried the do-it-yourself, stop-leak, A/C recharges available at stores like Advance and NAPA Auto?

Yes. I used this product in my sisters vehicle AC system when the evaporator developed a leak. She didn’t want to spend the money to replace the evaporator as the vehicle wasn’t worth it. This was added last summer and AC is still operating.

Tester