Vehicle: '95 Chevy Caprice 5.7L LT1 Mileage: 56k After I bought it, I had the valve covers resealed due to an oil leak. Leak was fixed and car does NOT use up or burn any oil now. Upon taking the valve covers off, there was sludge. I recently got the oil analysis back from the oil that was in when I bought the vehicle. It had a JiffyLube sticker so I'm assuming it was their house oil. Anyone know what it is? Full report can be seen here: https://bobistheoilguy.com/forums/ubbthreads.php/topics/4207811#Post4207811 Summary- high in Aluminum, chome, iron, and silicon. Wear at pistons, rings, and steal parts such as cylinders. I'm planning to do 2k OCI's. Should I go with diesel oil since it has more detergents? Cheap dino (currently have Havoline, Chevron Supreme, and maxlife in my stash)? Let it naturally clean slow and steady. Or take a more drastic approach and do an engine flush such as LiquidMoly or MMO. With the drastic approach, I'm scared of a big chunk of that black sand getting loose and then getting stuck on the oil pump screen frying the engine. PCV valve was all clogged up. It was changed.