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2018 GMC Sierra 3500HD maintenance schedule

Applies to: 6.6L Duramax L5P turbo-diesel V8 with the Allison 6-speed automatic (2500HD/3500HD pickups). Taken from GM's 2018 Duramax Diesel Supplement, which covers diesel-specific items; for other chassis items such as brakes, cabin filter and tires, see the regular 2018 Sierra owner's manual. Gas-engine Sierra HDs are not covered.

Schedule type: oil-life monitor (GM Engine Oil Life System)

The truck works out oil life from how it's driven and shows CHANGE ENGINE OIL SOON. When it does, change the oil and filter within 600 miles. Change it at least once a year even if the message hasn't come on. GM also wants a check visit every 7,500 miles. At that visit, check oil level and oil life, check coolant level, look for leaks, inspect the engine air filter, and look over the fuel and exhaust systems. Rotate the tires at the same visit. Summarized in our own words from the sources listed. Always follow the owner's manual or your dealer for your specific vehicle (VIN, engine, and options).

Checked against the official document for model year 2018; other years in this range are assumed to follow it. Confirm in your owner's manual.

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7,500 miles / 12 months

Repeat every 7,500 miles.

  • Check oil level and oil-life percentage; change engine oil and filter if needed and reset the oil life system replaceDIY

    Change within 600 miles of the CHANGE ENGINE OIL SOON message, and at least once a year. GM requires CJ-4 or CK-4 rated engine oil for the 6.6L.

    Parts: Oil filter

  • Rotate tires and do GM's required services: check coolant level, look for fluid leaks, inspect the engine air filter, and look over the fuel system, exhaust and heat shields rotateDIY

22,500 miles / 24 months

Repeat every 22,500 miles or 2 years.

  • Replace fuel filter replaceShop

    Every 22,500 miles or 2 years, or sooner if the CHANGE FUEL FILTER message comes on.

    Severe service: More often with biodiesel, heavy dust, off-road driving or long periods of towing.

    Parts: Fuel filter

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45,000 miles / 48 months

Air filter: repeat every 45,000 miles or 4 years.

  • Replace engine air cleaner filter replaceDIY

    Every 45,000 miles or 4 years. In dusty conditions, inspect it at every oil change.

    Parts: Engine air filter

  • Change automatic transmission external filter (2500/3500 pickup) replaceShop

    GM's chart lists this at 45,000 and 150,000 miles.

    Parts: Transmission external filter

  • Change automatic transmission fluid and filter (severe schedule) replaceShop

    Severe schedule only: every 45,000 miles. On the normal schedule it's at 97,500 miles.

97,500 miles

  • Change automatic transmission fluid and filter (Allison 6-speed) replaceShop

    Normal schedule: GM's chart, which runs to 150,000 miles, lists this once, at 97,500 miles.

    Severe service: Every 45,000 miles on the severe schedule.

150,000 miles / 60 months

  • Drain and fill engine cooling system (DEX-COOL) replaceShop

    Every 150,000 miles or 5 years, whichever comes first.

  • Visually inspect accessory drive belts inspectDIY

    Every 150,000 miles or 10 years. Replace if frayed, badly cracked or damaged.

Sources

Always follow the owner's manual for your exact vehicle; intervals can differ by engine and market.

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