Looking for an oil additive to supress a small leak.
Don’t.
If it’s a gasket leak a stop-leak additive won’t work. If it’s a seal leak and it’s a small leak you might try a high mileage oil such as Valvoline Max Life. These high mileage oils contain additives that stop small oil seal leaks.
Tester
If it’s small, do you bother? If it needs to be fixed, it needs to be fixed properly. If it’s like my Camry’s leak (loses maybe a few tbsp every 6 months), then don’t bother, IMO.
Look in the parts store. On the shelf.
If you’d like to properly correct the leak, be much more specific.
You might try one of those ‘high miles’ oils that swell seals to reduce leaks.
If the “high miles” oil does not work, just spread some kitty litter on your garage fl;oor. As others say, small oil leaks are not worth fixing.