The issue with biodiesel is that it oxidizes easily in the presence of ZDDP. One study that did a 4-ball wear test with diluted oil found a small increase in wear with 1% aged biodiesel in the oil, and a doubling of wear at 5% dilution. Regular diesel actually reduced wear slightly even at 5% dilution.
If the fuel you're using only has ~10% biodiesel, the amount of biodiesel in your oil should always be
The ACEA and MB 229.5x oil standards have engine tests to measure an oil's performance with biodiesel dilution, whereas API CK-4 doesn't seem to have a biodiesel test. MB 229.52 has the most stringent biodiesel tests, but is only available in grades up to 5W.