High oil consumption in your 2018 Jeep Grand Cherokee at 100,000 miles requires investigation to determine the cause. The Pentastar 3.6L V6 has some known oil consumption characteristics, but excessive burning indicates issues needing attention.
Normal vs Excessive Consumption
Some oil consumption between changes is normal - manufacturers may consider up to a quart per 1,000 miles acceptable in their specifications. At 100,000 miles, consumption increases from new. More than a quart per 500-750 miles is excessive and warrants diagnosis.
Common Causes in the Pentastar V6
Valve stem seal degradation allows oil into the combustion chamber through valve guides. Piston ring wear lets oil past the rings. The Pentastar has had PCV system issues that increase crankcase pressure. Oil cooler and filter housing leaks are common but typically create external leaks rather than burning.
Diagnostic Approach
Track consumption precisely - check oil weekly and record additions. Look for blue smoke from the exhaust, especially on startup or deceleration. Check for external leaks that might be mistaken for burning. A compression and leak-down test reveals ring condition. Smoke on startup suggests valve seals; constant smoke suggests rings.
Management Options
For moderate consumption, monitoring and adding oil may be acceptable. Valve seal replacement is less invasive than ring repair. Consider if the cost of any repair makes sense relative to the vehicle's value. High-mileage oil formulations may help slightly but don't fix worn components.