The 2020 GMC Sierra 1500 belongs to the T1 generation (2019-2021 powertrains) (2019-2021), built with 4.3L EcoTec3 V6 (LV3), 2.7L Turbo I4 (L3B), 5.3L EcoTec3 V8 (L82/L84, DFM), 6.2L EcoTec3 V8 (L87, DFM, 4WD only), or - from MY2020 - the 3.0L Duramax I6 turbodiesel (LM2). It takes dexos1 full synthetic - 0W-20 (5.3L/6.2L V8) or 5W-30 (2.7L Turbo and 4.3L V6); dexosD for the 3.0L Duramax. Oil changes run 7,500 miles typically, per the GM Oil Life Monitor. This is an early year of that generation, which usually means a handful of running changes were still being made.
A 2020 GMC Sierra 1500 is 6 years old in 2026, which at an average 12,000 miles a year puts it around 72,000 miles - the interval that decides its future. At roughly 72,000 miles a vehicle enters the window that most separates the ones that reach 200,000 miles from the ones that do not. Keeping up with whatever its own manufacturer schedule calls for here is what avoids expensive failures later. On that mileage estimate it is already past its 60,000-mile service, which its own schedule lists as: Replace spark plugs and inspect spark plug wires - 2.7L L4 Turbo only.
The fault most worth knowing about on this generation is 2.7L Turbo oil consumption above roughly 1 qt/1,000 mi on early-production units. Owners also report DFM lifter wear on the 5.3L L82/L84 and 6.2L L87; and 3.0L Duramax DEF system faults from contaminated DEF or a failed NOx sensor. None of these are certainties on any individual vehicle - they are the patterns worth checking for when you buy or when a symptom appears.
Track your 2020 GMC Sierra 1500 service history free with the ServiceSage maintenance tracker, or compare it against other model years on the GMC Sierra 1500 maintenance schedule hub.
| Interval | Service |
|---|---|
| Every 7,500 mi (per GM Oil Life Monitor) | Engine oil and filter change (dexos1 - per your specific gas engine's viscosity grade), Reset the Oil Life Monitor, Check tire inflation pressure |
| Every 7,500 mi (per GM Oil Life Monitor, 3.0L Duramax diesel) | Engine oil and filter change with dexosD - the 3.0L Duramax does not take dexos1, Reset the Oil Life Monitor |
| Every 7,500 mi | Rotate tires and perform Required Services, Visually inspect steering, suspension, and chassis components, Visually check for fluid leaks |
| Every 22,500 mi | Replace passenger compartment (cabin) air filter |
| Every 45,000 mi | Inspect evaporative control system fuel/vapor lines and hoses, If not equipped with the Engine Air Filter Life system, replace engine air cleaner filter |
| Every 45,000 mi (severe duty: towing/trailering/off-road) | Change automatic transmission fluid and filter |
| Every 97,500 mi (transfer case fluid, 4WD, GVW under 8,600 lb) | Change transfer case fluid, if equipped with 4WD |
| Every 45,000 mi (transfer case fluid, 4WD, GVW over 8,600 lb) | Change transfer case fluid, if equipped with 4WD |
| Every 60,000 mi (2.7L Turbo spark plugs) | Replace spark plugs and inspect spark plug wires - 2.7L L4 Turbo only |
| Every 97,500 mi (5.3L/6.2L V8 and 4.3L V6 spark plugs) | Replace spark plugs and inspect spark plug wires - 5.3L V8, 6.2L V8, and 4.3L V6 |
| Every 150,000 mi (or 5 years) | Drain and fill engine cooling system with DEX-COOL |
| Every 150,000 mi (or 10 years) | Visually inspect accessory drive belts; replace if frayed, cracked, or damaged |
| Every 75,000 mi (or 10 years) | Replace hood gas struts and tailgate dampener |
The table above is indexed by service interval. This is the same schedule indexed by odometer reading, for when you know your mileage and want the list. If your odometer sits between these figures, work back to the last one you passed and catch up anything skipped.
| Odometer | Service due |
|---|---|
| 30,000 mi (48,000 km) | Engine oil and filter change (dexos1 - per your specific gas engine's viscosity grade), Reset the Oil Life Monitor, Check tire inflation pressure, Engine oil and filter change with dexosD - the 3.0L Duramax does not take dexos1, Rotate tires and perform Required Services, Visually inspect steering, suspension, and chassis components, Visually check for fluid leaks. The every-22,500 mi service runs on its own cycle - the nearest fall at 22,500 and 45,000 miles. |
| 60,000 mi (97,000 km) | Engine oil and filter change (dexos1 - per your specific gas engine's viscosity grade), Reset the Oil Life Monitor, Check tire inflation pressure, Engine oil and filter change with dexosD - the 3.0L Duramax does not take dexos1, Rotate tires and perform Required Services, Visually inspect steering, suspension, and chassis components, Visually check for fluid leaks, Replace spark plugs and inspect spark plug wires - 2.7L L4 Turbo only. The every-22,500 mi service runs on its own cycle - the nearest fall at 45,000 and 67,500 miles. |
| 90,000 mi (145,000 km) | Engine oil and filter change (dexos1 - per your specific gas engine's viscosity grade), Reset the Oil Life Monitor, Check tire inflation pressure, Engine oil and filter change with dexosD - the 3.0L Duramax does not take dexos1, Rotate tires and perform Required Services, Visually inspect steering, suspension, and chassis components, Visually check for fluid leaks, Replace passenger compartment (cabin) air filter, Inspect evaporative control system fuel/vapor lines and hoses, If not equipped with the Engine Air Filter Life system, replace engine air cleaner filter, Change transfer case fluid, if equipped with 4WD. |
| 120,000 mi (193,000 km) | Same as the 60,000 mi service. The every-22,500 mi service runs on its own cycle - the nearest fall at 112,500 and 135,000 miles. |
| 150,000 mi (241,000 km) | Engine oil and filter change (dexos1 - per your specific gas engine's viscosity grade), Reset the Oil Life Monitor, Check tire inflation pressure, Engine oil and filter change with dexosD - the 3.0L Duramax does not take dexos1, Rotate tires and perform Required Services, Visually inspect steering, suspension, and chassis components, Visually check for fluid leaks, Replace hood gas struts and tailgate dampener, Drain and fill engine cooling system with DEX-COOL, Visually inspect accessory drive belts; replace if frayed, cracked, or damaged. The every-22,500 mi service runs on its own cycle - the nearest fall at 135,000 and 157,500 miles. |
| Part | Fitment note | Buy |
|---|---|---|
| Mobil 1 0W-20 Full Synthetic (5 qt) | dexos1-approved 0W-20 - required for the 5.3L and 6.2L gas V8 | Check price on Amazon |
| ACDelco dexos1 5W-30 Full Synthetic (5 qt) | dexos1-approved 5W-30 - required for the 2.7L Turbo I4 and the 4.3L V6 | Check price on Amazon |
| ACDelco dexosD 0W-20 Full Synthetic Diesel Oil (1 qt) | OEM-spec oil for the 3.0L Duramax LM2 | Check price on Amazon |
| GM Genuine DEXRON-HP ATF Transmission Fluid (1 qt) | Required for the 8L90 8-speed only - not interchangeable with DEXRON ULV | Check price on Amazon |
| GM Genuine DEXRON ULV Automatic Transmission Fluid (1 qt) | Required for the 10L80/10L90 10-speed only | Check price on Amazon |
| ACDelco 41-114 (12622441) Iridium Spark Plug | 97,500-mile plugs for the 5.3L/6.2L V8 and 4.3L V6 | Check price on Amazon |
| BlueDEF Diesel Exhaust Fluid, 2.5 gal (2-pack) | ISO 22241-compliant DEF for the 3.0L Duramax | Check price on Amazon |
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| Fastener | Torque | Size |
|---|---|---|
| Lug nut | 140 ft-lbs (190 Nm) | 22mm |
| Oil drain plug | 18 ft-lbs (25 Nm) | 15mm |
Maintenance keeps these away, but when the dash does light up these are the codes this vehicle throws most often - each with what it means and what the repair actually costs.