Just Bought a Used RAM 2500 Cummins? The 5 Mopar Filter Changes to Do FIRST
You finally pulled the trigger on a used RAM 2500, 3500, 4500, or 5500 with the 6.7L Cummins. Congratulations — you bought one of the most reliable diesel platforms ever built. Now here's the hard truth: the previous owner probably lied about maintenance. Even if they didn't, you have no idea what filters are in that truck right now or how long they've been there.
Before you tow anything, before you take that first long road trip, do these five mopar filter changes. Together they cost less than $100 and can save you a $9,000 CP4.2 pump. This is the smartest first move any used Cummins owner can make.
Why You Can't Trust the Previous Owner's Records
Most used trucks come with a stack of receipts that look reassuring — until you read them carefully. Common red flags:
- "Oil change" with no filter brand listed (probably a $4 cheap aftermarket filter)
- Records that skip the fuel filter entirely (extremely common)
- Mixed brands of fuel filters between services (signs of corner-cutting)
- No record of the chassis-mounted water separator ever being changed
- 30,000+ miles between fuel filter services
If the records are vague or missing, assume the worst and reset the maintenance clock. Genuine american mopar filters installed by you are the only filters you can fully trust.
Filter Change #1: The Engine Oil Filter (5083285AA)
Start here. The oil filter is the easiest to change and the most universally needed. The mopar 5083285AA fits every Cummins-powered RAM from 1989 to 2024 — that's 35 years of fitment in one part number, so you know it's the right one.
Pair the filter change with fresh diesel-rated 15W-40 motor oil. Cut open the old filter when you remove it — the metal particles you find tell you a lot about how the previous owner treated this engine.
Grab the Mopar Oil Filter 5083285AA for 1989-2024 RAM 2500/3500 5.9L & 6.7L Cummins at $24.99 — genuine OEM, factory-spec filtration.
Filter Change #2 & #3: Both Fuel Filters
Your CP4.2 high-pressure pump is the most expensive component in the truck and the most fragile. Two fuel filters protect it. Change both. No exceptions.
For 2019-2024 trucks: You need the 68157291AA (engine-mounted NanoNet) and the 68436631AA (chassis-mounted water separator). Get both together in the Mopar Fuel Filter Kit 68157291AA + 68436631AA for 2019-2024 RAM 2500-5500 at $54.99.
For 2013-2018 trucks: You need the 68157291AA plus the older 68197867AB chassis filter. The Mopar Fuel Filter Set 68197867AB + 68157291AA for 2013-2018 RAM at $44.99 has both genuine filters in one shipment.
Mopar fitment matters here — the 2019+ chassis filter is physically different from the 2013-2018 version. Confirm your model year before ordering.
Filter Change #4: Drain the Water Separator
While you're under the truck changing the chassis-mounted fuel filter, drain the water separator completely. Used trucks that sat at dealer lots for months often have water accumulation in the fuel system from condensation. Drain it now or it will trigger a "Water in Fuel" warning light within a thousand miles.
Filter Change #5: Cabin Air Filter (Bonus, But Do It)
Not on your engine, but trust me — pull the cabin filter on a used truck. You'll be horrified. Pet hair, leaves, and ten years of dust are sitting in your HVAC system. It's a five-minute change that makes the truck feel new again.
The Smart Move: Bundle Everything
Buying filters separately wastes shipping and time. Most first-time used-truck owners go for the complete service kit and knock out all three engine-critical filters at once.
For 2019-2024 trucks, the Mopar Fuel & Oil Filter Kit 68157291AA + 68436631AA + 5083285AA at $62.99 is everything you need in one box.
For 2013-2018 trucks, the Mopar Oil & Fuel Filter Kit 5083285AA + 68197867AB + 68157291AA does the same job at the same price.
Don't Wait, Don't Cheap Out
You wouldn't trust a stranger's word on the service history of your house's foundation. Don't trust it on a 6.7L Cummins either. Skip the mopar coupons lottery and the dodge ram oil change coupons at the dealer — buy genuine OEM filters once, install them yourself in an afternoon, and start your ownership from a clean baseline.
Your future self, hauling 12,000 pounds up a grade in five years, will thank you.