2026 Ram 3500
Maintenance Schedule
If you own a 2026 Ram 3500, you didn't buy it for grocery runs. You bought it to pull heavy machinery, livestock, or massive 5th wheels across Oklahoma. Unlike the lighter-duty trucks, the Ram 3500, specifically with the High Output (HO) Cummins, is an industrial tool.
Many Kingfisher owners trade in their 2022 models and assume the maintenance is the same. It isn't. The 2026 HO Cummins features tighter tolerances, and the Aisin AS69RC transmission has a completely different service life than the standard transmission.
Neglecting this schedule doesn't just void your warranty; it kills your resale value. Here is the definitive guide to maintaining the beast, directly from the service experts at Johnsons of Kingfisher.
Critical Difference: The "Severe Duty" Reality
Let's be honest: If you live in Kingfisher County, you are a "Severe Duty" driver.
- Do you tow more than 50% of the time? Yes.
- Do you idle while loading cattle or at a job site? Yes.
- Do you drive on dusty lease roads? Yes.
Action: Ignore the "Normal Duty" schedule in the back of the owner's manual. It is written for highway cruisers. Follow the Severe Duty schedule below to protect your investment.
2026 Ram 3500 (HO Cummins) Service Intervals
| Mileage Interval | Service Required | Why It Matters for the High Output Engine |
|---|---|---|
| Every 7,500 Miles (or 6 mo.) | Oil & Filter Change | The HO Cummins runs hotter than the standard output. Oil breakdown is the enemy of the turbo bearings. |
| Every 15,000 Miles | Replace Fuel Filters (Front & Rear) | Critical: The HO fuel system pushes immense pressure. Dirty fuel destroys injectors instantly. |
| Every 30,000 Miles | Aisin Trans Fluid & Filter | Different than 2500: The Aisin transmission requires service twice as often as the standard 68RFE. |
| Every 30,000 Miles | Transfer Case Fluid | Heavy towing puts massive stress on the 4WD system. Keep this fluid fresh. |
| Every 50,000 Miles | Crankcase Ventilation (CCV) Filter | A clogged CCV causes oil leaks. If you see an “Oil Change Required” message early, check this. |
| Every 75,000 Miles | Coolant Flush | Essential for preventing cavitation in the cylinder liners. |
The Aisin AS69RC Transmission: A Special Case
If you have the High Output engine, you have the Aisin transmission. This is a commercial-grade unit used in box trucks.
- Fluid Type: It does NOT use ATF+4. It requires Aisin ASRC Fluid. Putting standard ATF in this transmission will ruin the clutch packs.
- Service Interval: You must change the fluid and sump filter every 30,000 miles.
Warning: Many quick-lube shops will skip this because dropping the pan is "too much work." At Johnsons, we do it right every time.
Dually (DRW) Tire Rotation: The "X" Factor
Rotating tires on a Dually is more complex than a standard truck. You cannot just swap them front-to-back because the inner rear wheels are often steel, while the outer wheels are aluminum (for looks).
The Procedure:
1. Fronts: Swap side-to-side.
2. Rears: If you have aluminum outers, dismount the tires to rotate them properly (a service we offer). If you have steel wheels all around (Tradesman), you can rotate the inners to the front.
Fuel & Fluids: What to Use
- Engine Oil: 12 Quarts of SAE 10W-30 (Preferred for 2026 models) or 5W-40 Synthetic for severe cold.
- DEF: The 3500 has a 5.5-gallon DEF tank. When towing heavy, expect to refill this every 3-4 fuel fill-ups.
- Fuel: Only use Ultra-Low Sulfur Diesel. We highly recommend using a Mopar fuel additive in the winter to prevent gelling.
Why Service at Johnsons of Kingfisher?
We are one of the few dealerships in Central Oklahoma with Heavy Duty Certified lifts capable of lifting a loaded Ram 3500 Dually.
- Parts Availability: We stock Aisin filters and ASRC fluid in bulk.
- Tech Training: Our techs know the difference between the 68RFE and the Aisin. We won't put the wrong fluid in your $12,000 transmission.
* The advertised price does not include sales tax, vehicle registration fees, other fees required by law, finance charges and any documentation charges. A negotiable administration fee, up to $115, may be added to the price of the vehicle.
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* Price does not include $89 doc fee.