Oil residue around the filter housing cap on the 2GR-FKS engine can sometimes occur, even when everything is properly torqued and the O-ring is replaced. Although not highly prevalent, minor issues with the cartridge filter housing might lead to such leaks. It’s essential to ensure that the O-ring is correctly seated in its groove and uniformly lubricated.
In terms of best practices, avoid over-lubricating the O-ring to prevent it from slipping out of place during installation. Double-check the cap for any signs of damage, like hairline cracks, which could contribute to leaking. While I haven’t seen any specific TSBs addressing this directly on your model, periodically checking Lexus Enthusiast forums or official service bulletins is a good practice to catch any updates.
For persistent issues, it might be worth inspecting or upgrading to the latest part revision if available. Additionally, ensure there is no residual old oil caught in the housing that might give a misleading appearance of a leak. If everything still checks out, it might just be a sensitivity in the design to perfectly clean assembly conditions.