It is now well-known that not only dimensions but also manufacturing tolerances and layouts of oil holes and grooves affect engine bearing performance. The present paper will show that some new features of machining and operating conditions can also influence bearing operation. Scratches caused by debris in the oil and the size of the counterbore on cross-drilled main journals can have highly detrimental effects. Results will also show how out-of-roundness and ellipticity affect bearing operation. This information can be vital for designing better engine bearings.