Why do I have excessive RPMs while driving, but the transmission is shifting normally?
Repair cause of oil leak at oil filter block leading to radiator.
The leak is coming from the Engine Oil Cooler block. You will need to remove the two retaining bolts from the cooler block and replace the gasket. This is a common gasket failure.
Engine Oil Cooler Description and Diagram
The oil cooler is located in the left side of the radiator. Engine oil flows through the cooler and reduces the temperature of the engine oil. The cooled engine oil then returns to the engine.
Here is the gasket you need for under $10. I double checked to make sure it will fit on your specific engine.