Here is a nice thread for those wanting a cut open view of a QS and Pennzoil filters. One caveat, in the thread the OP refers to the QS and PZ as a Purolator Classic, which implies the same efficiency @97.5% as the Classic. While they are constructed and look very similar to the Classic or even P1, it's questionable they are built to the same efficiency spec. The AAP Total Grip media (left) looks nearly identical to the P1 in the pic below. Yet the P1 is rated at 99.9% while the AAPTG is rated at 94%. That said, I use the AAPTG (now discontinued) for ~5k OCI's all the time, a solid filter and value. Wish I could still get them, and likely the QS and PZ is closer to the TG, IMO.