Whether you drive your Jeep across the Rockies or across town, you know how important reliability is. Your rig has to be well prepared and have proven parts to get through and return intact. While exploring in Third World countries with our Jeep XJs, we learned the hard way that finding replacement parts can be very difficult.
We use Cherokees and Comanches with 4.0L inline six-cylinder engines. During model years 1987 through 1990, these rigs came from the factory with a small, upside-down oil filter that had rare M20x1.5 metric threads. These can be difficult or impossible to find in remote areas, and they cost more and hold less oil than more common filters and make a mess when you remove them. As a result, we developed some oil filter modifications to solve these problems.
There are two ways to fix these problems. If you're short on cash, you can rid your Jeep of the small metric oil filter and upgrade to a more common, larger oil filter by simply replacing the screw-in threaded connector in the oil filter adapter mounted on the side of the engine. Jeep identifies this part as connector PN 53007563, which retails for about $4.26. Simply unscrew the old one using a deep socket and screw in the new one. Then you can use an oil filter like the K&N PN HP-3001 or an equivalent. However, when it's time to change filters, the oil will still run down the side of the engine and onto the suspension parts.
Our favored upgrade is to change over to the 1991-and-newer Jeep oil filter setup. This adapter will provide increased filtration and capacity, and it uses the more common filters. We purchased the following parts at Santa Ana, California, Chrysler/Jeep: Adapter (body), PN 53020080, $25.80; bolt, PN 53020237, $14; seal (O-rings), PN 4720363, $3.64, and the connector described previously, PN 53007563. This setup will move the filter to aft of the adapter, and the passages in the new housing will have larger openings for more flow.
You'll also find that there's less mess when you change filters. After many miles and a great deal of comparison testing, our filter of choice for this application is a K&N HP-3001. It produces higher oil flow rates of between 12 and 16 gallons per minute (GPM), compared to stock rates of around 8-10 GPM. It has a hex on the filter body so you don't need a special oil filter wrench to remove it. That's a really nice feature when you're out on the trail and have to change the oil after the engine takes a dunking on a river crossing.
Additionally, the heavy-duty construction (double OEM specs) of the K&N provides over 550 psi of bursting strength. That's nice to know as you start up on a frigid morning in the mountains, when the oil pressure gauge is pegged on Maximum, or when stones are bouncing off the filter on a gravel road. Demanding situations demand the best parts, and K&N is our proven winner. Whichever oil-filter setup you choose, we're confident you'll enjoy the improvement.