You might think that a clean engine compartment is a good thing. Unfortunately, the opposite is often the case. Shady car dealers and private sellers will steam clean or power wash the engine compartment to hide leaks and other problem areas. On an inline-six Jeep, the valve cover, oil pan, and often the valve cover breather gaskets tend to leak. Some seepage is OK, but puddles under the Jeep aren’t. You can also check T-case, manual transmission, and differential fluids, but unless something is very wrong with these parts, a fluid check will reveal nothing. And, if something is really wrong, it will usually show up on the test drive.