Did my second oil change and first fuel filters change on my 2018 RAM -
My fuel filter life was at 10%. My truck has 12,500 miles or so on it. I'm doing oil changes every 6k. I know there are tons of arguments about going to 15k or longer, but I'm not here to argue about that.
Coming from a Ford 6.7L, neither oil nor fuel filter changes are as easy on the RAM. The fuel filter under the hood on the Ford is right on top and can literally be swapped out in less than one minute with zero mess. But let's move on to the RAM.
I did the fuel filters first, since you are working in the vicinity of the exhaust for the rear filter. It's nicer to have it cold and you can grab on to the pipe to move yourself around.
I started with the engine fuel filter, but it really doesn't matter the order. You drain the filter housing, which has a nice bright yellow quarter-turn pet valve, and even a drain hose. Problem is that the drain hose terminates right above the front axle. I used a kitty litter box and put it roughly under the hose, under the axle. It drains out well, pours over the axle, and ends up in the container.
I bought the dogbone combo tool from Geno's garage. It fits in the fuel filter housing cap nicely but there is very little room to turn it. However, with a little patience, it can be done. More fuel will drain out once the cap is cracked open. Take the cap off and set it on top of your engine valve cover. Remove the o-ring at the bottom of the threads on the filter housing. Smear some clean motor oil on the new o-ring and fit it into the groove on the housing. Remove the old filter; install the new filter and make sure it snaps down. Put the cap back on and snug it tight. I think a socket would be easier to remove the cap in the future.
Next I did the rear filter. Slide under the truck from the passenger side just ahead of the rear wheels. First, unplug the WIF sensor harness (blue connector, easy). This filter has a threaded drain valve in the bottom of the WIF sensor, which also threads into the bottom of the filter. Open the drain and basically nothing comes out. Use the kitty litter pan again and get it underneath. Now use a standard oil filter wrench on the lower, smaller diameter portion of the filter canister and start loosening it. At some point, diesel will come out the bottom and maybe the top too, and make a mess on your arm. Have shop towels nearby. Remove the filter the last little bit by hand, then up-end it into the container to drain out the rest of the fuel. You will smell like an oil burner technician at this point.
Crawl back out and set the oil filter on your tailgate. Put the oil filter wrench back on the filter, and the dogbone tool on the hex of the WIF sensor. Unthread the sensor from the old fuel filter. Discard the old filter. An OEM filter includes a new o-ring for the WIF sensor and a new seal ring for the filter itself. Remove the old o-ring from the WIF sensor, smear a little clean motor oil on the new o-ring, install it in the groove, and then using the two wrenches again, thread and snug the WIF sensor into the new filter canister. Now lightly smear a little clean oil on the seal and set it into place. Slide back under the truck and clean the mating surface of where the filter mounts. Now thread the new filter in, snug it but don't overtighten. Re-connect the WIF sensor blue plug. Now close the pet drain. On mine, it seemed to be the reverse of what you'd expect to open / close.
So your filters are done and you need to do the prime procedure, which is simple. Turn the key on to the second position where all your warning lights come on, wait 5 seconds, shut the key off, repeat 4 times. Now, start your engine. It might take some additional cranking, and might run choppy for a couple of seconds. Once running, check for leaks at the front and rear, and let it idle for 5 minutes or so to warm the engine oil. While it's idling, pour the diesel fuel you collected into a container. Mine was about a third of a gallon. If you live in the northeast like me, most people heat with a fuel oil furnace. I just poured my diesel into the furnace oil barrel. Otherwise, save it until you need to start a bonfire. Don't reuse it in your truck.
Shut her down and start the oil change. Slide under from the front of the truck with a 3/8" socket. Slide your oil drain pan capable of holding at least 3 gallons under the truck. There is no drain plug "bolt" but rather just a recessed plug with a square 3/8" female opening. The entire oil pan will flex and bend if you reef too hard, so just loosen it, remove the plug, and wait for it to drain. Cracking the oil filler cap and dipstick seems to help it drain faster, so you can do that too. Once some of it drains, you can commence with the filter. Some people pull off the turbo intake plumbing and do the whole procedure from the top, but I think it's quicker to do the factory-recommended through the fender method. It can be a real pain to get the large intake plumbing fully seated back on right at the turbo, and sometimes you spend more time on that than you'd like. For filter removal, go through the side fender opening with your oil filter wrench. Get it loose, then spin it down by hand. If you let the engine run too long, the filter will be extremely hot. I lower the filter down until it stops and sits against whatever is in the way underneath. I did buy the Geno's oil filter cap...thread it in place, then turn the filter sideways and out through the fender opening without spilling any. Some folks just use a zip-lock bag and let the oil spill into the bag and throw the whole thing out. But really, you should drain the oil out of the filter before discarding. At this point, even though you can't easily see it, I take a clean rag and clean the mating surface of the filter mount. Next, I prefill the new filter with fresh oil to lessen that tiny bit of extra wear during initial startup. If you do this, you need to cap the filter again or the oil will spill out when it goes through the fender sideways. Remove the cap, raise the filter, and find the threads. Tighten until it stops, then turn an extra quarter to half turn. Reinstall the drain plug and snug it. Refill the engine oil sump - I usually go a quart less in case you didn't get everything out. Start the engine, check for leaks, watch your oil pressure warning go out. Run for a minute and shut down. Let it sit for 5 or 10 minutes, then check the oil level on the dipstick. If it's low, add some or all of your leftover quart until it's full. Clean up, reset your fuel filter and oil change reminders on the dash, record your mileage and hours, and keep your receipts and documentation in a folder.
For what it's worth, I buy Rotella T6 synthetic oil - I can get 3 gallons shipped to my door with Amazon prime for $55. I use only Mopar or Fleetguard filters. On this last service, with fuel and oil, my total cost was $186. On a standard oil change, it's about $65. Compared to the dealer, you save money and have the satisfaction of doing the work yourself, getting to know your truck more, and likely doing a better job. Don't forget to grease your front driveshaft u-joint every other change.
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