When to Replace Spark Plugs: Mileage Intervals and Manufacturer Schedules
Most articles give generic "30k-100k miles" advice. This page includes specific manufacturer recommendations for 15 popular vehicles and explains when to deviate from the book.
Quick Answer: Intervals by Plug Type
Copper
30,000 mi
Most frequent
Platinum
60,000 mi
Mid-range
Double Platinum
80,000 mi
Distributor systems
Iridium
100,000 mi
Most modern cars
Ruthenium
120,000 mi
Extended life
Owner's manual overrides these numbers. If your manual says 60,000 miles for iridium, follow the manual.
Manufacturer Schedules for 15 Popular Vehicles
"Our recommendation" deviates from the manufacturer when there are known reasons (turbocharged engines, specific design issues) to service earlier.
| Vehicle | Years | OEM Plug | Mfr Interval | Our Rec | Notes |
|---|---|---|---|---|---|
| Toyota Camry (4-cyl) | 2012-present | NGK Iridium | 120,000 mi | 100,000 mi | Toyota extends interval but check at 80k |
| Honda Civic | 2016-present | NGK Iridium | 105,000 mi | 90,000 mi | 1.5T turbo runs hot - check earlier |
| Ford F-150 (EcoBoost) | 2015-present | Motorcraft Platinum | 60,000 mi | 60,000 mi | Turbocharged - follow Ford schedule strictly |
| Chevrolet Silverado (5.3L) | 2014-present | ACDelco Iridium | 100,000 mi | 100,000 mi | Good track record. Follow GM schedule. |
| Honda Accord (4-cyl) | 2018-present | NGK Iridium | 105,000 mi | 90,000 mi | 1.5T - runs lean, check at 80k if towing |
| Toyota RAV4 | 2019-present | Denso Iridium | 120,000 mi | 100,000 mi | Reliable interval. Hybrid variant does not have plugs on EV wheels. |
| Toyota Corolla | 2020-present | Denso Iridium | 120,000 mi | 100,000 mi | Conservative Toyota schedule. |
| Honda CR-V | 2017-present | NGK Iridium | 105,000 mi | 80,000 mi | 1.5T turbo. Honda oil dilution issues make earlier replacement prudent. |
| Subaru Outback | 2015-present | NGK Iridium | 60,000 mi | 60,000 mi | Boxer runs cooler. Subaru 60k schedule is correct. |
| Hyundai Elantra | 2017-present | NGK Iridium | 97,500 mi | 90,000 mi | Follow Hyundai schedule. GDI engines benefit from slightly earlier replacement. |
| Nissan Altima | 2019-present | NGK Iridium | 105,000 mi | 100,000 mi | VC-Turbo engine. Follow Nissan schedule. |
| Ford Escape (1.5T) | 2020-present | Motorcraft Platinum | 60,000 mi | 60,000 mi | Turbocharged. Ford 60k schedule. Do not delay. |
| Chevrolet Equinox | 2018-present | ACDelco Iridium | 97,500 mi | 90,000 mi | 1.5T. Turbocharged 4-cyl - check at 80k. |
| Jeep Grand Cherokee (3.6L) | 2011-present | Champion Iridium | 102,000 mi | 90,000 mi | V6 rear bank difficult - worth doing early to avoid added cost |
| Toyota Tacoma (2.7L) | 2016-present | Denso Iridium | 120,000 mi | 100,000 mi | Naturally aspirated. Toyota long intervals are reliable. |
Red "Our Rec" = earlier than manufacturer spec. These are turbocharged or problematic engines where early replacement is prudent.
Replace EARLY if:
- !High-mileage vehicle with unknown plug history (replace immediately on purchase)
- !Car primarily driven in stop-and-go city traffic (plugs degrade faster)
- !Vehicle used for towing or heavy hauling (higher combustion temps)
- !Any active misfire symptom regardless of mileage
- !After a head gasket repair (coolant contamination fouls plugs)
- !Turbocharged engine approaching 80 percent of its rated interval
You can wait if:
- +Low-mileage garage queen with iridium plugs at 50k miles and running perfectly
- +Vehicle being sold within 6 months (disclose age to buyer)
- +Car with platinum plugs at 50k if no symptoms present
- +Recently purchased used car that has documented plug replacement history
What Happens If You Never Replace Them
Progressive failure timeline for a car with iridium plugs that are never replaced:
100k - 110k miles
Slight rough idle begins
$150
Replacement cost
110k - 120k miles
Noticeable MPG drop
$200-$350
Added fuel waste + replacement
120k - 130k miles
Check engine light + misfire codes
$350-$600
Diagnostic + replacement
130k+ miles
Sustained misfires - catalytic converter damage
$1,000-$3,000+
Cat + O2 sensors + replacement
What Else to Do at the Same Service
Since you are already in the engine bay for a plug service, these inspections add minimal labor:
Inspect ignition coil boots
Cracked or oily boots cause misfires. Replace any that show deterioration. $5-$15 each in parts.
Check plug wire resistance
Only applies to older vehicles with distributor. Test with a multimeter: 3,000-10,000 ohms per foot is acceptable.
Clean throttle body
If you remove the intake for V6 rear bank access, clean the throttle body while it is off. $10 in spray cleaner.
Replace engine air filter
Accessible on most engines in 2 minutes. If you are paying a shop visit, check the filter condition.
Common Questions
How often do spark plugs need to be replaced?
Replacement interval depends on the plug material. Copper plugs: every 30,000 miles. Single platinum: every 60,000 miles. Double platinum: every 80,000 miles. Iridium: every 100,000 miles. Ruthenium: every 120,000 miles. Always check your owner's manual.
What happens if you don't replace spark plugs?
Progressive failure: 100k-110k miles = slight rough idle, 110k-120k miles = noticeable MPG drop, 120k-130k miles = check engine light with misfire codes, 130k+ miles = active misfires causing catalytic converter damage ($800-$2,500 to replace). A $150 maintenance job becomes a $1,500+ repair if delayed past the point of active misfiring.
Should I replace spark plugs at 100,000 miles even if the car runs fine?
Yes. The 100,000 mile interval is the maximum rated life, not the optimal replacement point. Most iridium plugs start to degrade noticeably between 80,000 and 90,000 miles. Replacing at 100,000 miles is scheduled maintenance, not optional.