Complete DIY Service Guide: Changing All 3 Mopar Filters on Your RAM 6.7L Cummins in One Afternoon

Dealer oil changes on a RAM 6.7L Cummins run $150-$250. Add the fuel filters and you're looking at $400-$600 for a service that takes a mechanic 45 minutes. The parts themselves cost under $65 when you buy genuine american mopar OEM filters at the right price. This guide shows you how to do the complete three-filter service yourself — oil filter, engine fuel filter, and chassis water separator — in one afternoon, with basic tools, no lift required.

What You Need Before You Start

Parts: The Mopar Fuel & Oil Filter Kit 68157291AA + 68436631AA + 5083285AA for 2019-2024 RAM at $62.99 includes all three genuine OEM filters for a complete service.

For 2013-2018 trucks, the Mopar Oil & Fuel Filter Kit 5083285AA + 68197867AB + 68157291AA is the equivalent complete kit at $62.99.

Tools:

• 28mm filter socket (fits both fuel filters and the oil filter)
• 3/8" ratchet with 6" extension
• Torque wrench
• Large drain pan (2-gallon minimum for oil)
• Small catch pan for fuel (half-pint capacity)
• Shop towels
• Blue nitrile gloves
• Fresh 15W-40 diesel-rated engine oil (approximately 3 gallons for the 6.7L)

Time: 90-120 minutes for a first-timer. 45-60 minutes once you've done it twice.

Service Order: Why Sequence Matters

Do the filters in this order for the cleanest, most efficient service:

1. Drain the chassis water separator first (while the engine is cold)
2. Drain the engine oil (while everything is still warm from a short drive)
3. Replace the chassis-mounted 68436631AA water separator
4. Replace the engine-mounted 68157291AA fuel filter
5. Replace the 5083285AA oil filter
6. Fill with fresh oil
7. Prime the fuel system
8. Start and check for leaks

This sequence keeps diesel off your hands before you handle oil, and lets the oil drain completely while you're working on the fuel filters.

Part 1: Chassis-Mounted Water Separator (68436631AA)

Locate the filter on the driver-side frame rail under the cab — roughly below the driver's seat. Place your small catch pan underneath.

Step 1: Open the drain valve at the filter bottom. Let all water and fuel drain completely — watch what comes out. Milky or cloudy fluid means significant water contamination.

Step 2: Disconnect the water-in-fuel sensor electrical connector. Squeeze the tab, pull straight out.

Step 3: Use the 28mm socket to unthread the filter counterclockwise. It will be stiff the first time.

Step 4: Unscrew the water-in-fuel sensor from the bottom of the old filter and thread it carefully into the new 68436631AA. Hand-tight plus a quarter turn — do not overtighten the sensor.

Step 5: Lubricate the new O-ring with clean diesel. Hand-thread the new filter until it contacts the housing, then tighten 3/4 turn with the socket. Reconnect the sensor connector.

Part 2: Engine-Mounted Fuel Filter (68157291AA)

The mopar 68157291AA fuel filter sits on the engine, driver's side, accessible from the top with a short extension.

Step 1: Place a small rag under the filter housing to catch drips.

Step 2: Use the 28mm socket to unthread the filter counterclockwise.

Step 3: Transfer the O-ring from the new filter packaging — do not reuse the old one.

Step 4: Lightly coat the new O-ring with clean diesel fuel.

Step 5: Hand-thread the new filter until contact, then tighten 3/4 turn. No more.

Part 3: Engine Oil Filter (5083285AA)

The mopar 5083285AA is accessible from underneath on 2013+ trucks — you'll need to slide under or use ramps.

Step 1: With the drain plug already out and oil draining into your large pan, locate the oil filter on the driver side of the engine block.

Step 2: Use the 28mm socket to remove the old filter. Have a rag ready — it will drip.

Step 3: Coat the new filter's O-ring with fresh engine oil.

Step 4: Hand-thread until contact, then tighten 3/4 turn. The quarter-turn indicator marks on the genuine mopar filter body make this foolproof — line up the mark and stop.

Step 5: Reinstall the drain plug with a new crush washer. Torque to 40 ft-lbs.

Part 4: Fill Oil and Prime the Fuel System

Oil fill: Add fresh 15W-40 to the fill cap on top of the engine. The 6.7L Cummins takes approximately 12 quarts with filter change. Fill to the full mark on the dipstick — not above it.

Fuel system prime: This step is critical and most first-timers skip it — don't.

1. Turn the ignition key to ON — do not crank
2. Hold for 30 full seconds
3. Turn OFF
4. Repeat 3-4 times

This lets the electric lift pump fill both new fuel filters completely before you ask the engine to start. Skip it and the engine cranks dry, stressing the lift pump and potentially introducing air to the CP4.2.

Part 5: Start and Inspect

Crank the engine. It may run rough for 15-30 seconds as residual air clears — this is normal. Let it idle for two minutes, then check:

• Both fuel filter housings for drips
• Oil filter for seepage
• Drain plug for weeping
• Oil level on dipstick after the engine has circulated oil

Wipe everything dry with a clean shop towel. Check again after a 10-minute drive. A properly installed genuine mopar filter will not leak.

What This Service Actually Costs You

Dealer price: $400-$600 including parts and labor DIY with genuine Mopar OEM kit: $62.99 in parts + 2 hours of your time

Over three years of ownership that's roughly $1,000-$1,500 saved — enough to buy 15-20 more complete filter service kits. And unlike the dealer, you know exactly what went into your truck.

Hunting dodge ram oil change coupons at the dealership to save $30 while paying $250 for a service you could do yourself for $63 is the most expensive way to maintain a Cummins. Mopar vehicle protection doesn't come from the dealership — it comes from the right filters installed correctly on schedule.