Install clean plugs, start-up cold (when smoking) shut off when still smoking, pull plugs and inspect. If it's cylinder specific you'll find it.

8-10% leak down on a new engine is too high assuming the test is done correctly. The engine should be hot. You may see 10% on a good engine if the test is done cold. False positive. The test is to be done at operating temperature. Get it good and warm 180+ and perform the leak-down.

The leak down only tests the compression rings for seal. The test does little for the oil rings.

When testing listen for leaking from crankcase (dipstick tube).