The 2008 Pontiac G6 uses SAE 5W-30 motor oil, and the exact amount depends on which engine you have: about 4.5 quarts for the 2.4-liter Ecotec and about 5 quarts for the 3.5-liter V6. Both conventional and synthetic oils meeting API service ratings are acceptable.
Engine options and oil requirements
2.4L Ecotec four-cylinder
The 2.4L Ecotec engine in the 2008 G6 shares the same basic oil viscosity recommendation, but its capacity is a bit smaller than the V6.
- Oil viscosity: SAE 5W-30
- Oil capacity (with filter): approximately 4.5 quarts (4.3 liters)
- Oil type options: conventional or synthetic oil that meets API service requirements
In short, the 2.4L Ecotec requires 5W-30 oil and takes roughly 4.5 quarts when changing the oil and filter.
3.5L V6
The 3.5L V6 option uses the same viscosity specification but holds more oil.
- Oil viscosity: SAE 5W-30
- Oil capacity (with filter): approximately 5.0 quarts (4.7 liters)
- Oil type options: conventional or synthetic oil that meets API service requirements
In short, the 3.5L engine calls for 5W-30 oil and uses about 5 quarts with a filter change.
Choosing the right oil and maintenance tips
Whether you choose conventional or synthetic oil, stick to the 5W-30 viscosity and ensure the oil meets current API service standards. The exact interval for oil changes depends on driving conditions and the oil type you choose, but conventional oil typically calls for more frequent changes than synthetic oil.
- Oil change intervals: conventional oil often requires 3,000–5,000 miles (4,800–8,000 km); synthetic oil can extend that range in favorable conditions. Always follow the manufacturer’s guidance and your vehicle’s maintenance schedule.
- When shopping for oil, look for API service ratings (such as SN, SM, or SL) and consider Dexos1-certified oils as an option, even though Dexos1 was introduced after 2009 and is not strictly required for a 2008 model.
- Filing and capacity: use the correct fill amount (4.5 quarts for the 2.4L, 5 quarts for the 3.5L) and recheck with the dipstick after a fill to ensure proper oil level.
Regardless of engine, the key is to maintain the correct viscosity and API rating, and to follow the maintenance schedule for timely oil changes.
Where to verify the exact specification for your car
Consulting the owner's manual is the best way to confirm the recommended oil type and capacity for your specific G6, especially if you’re unsure which engine you own. If you no longer have the manual, many automaker repositories and automotive databases list the same 5W-30 recommendation for both engines, along with the approximate capacities mentioned above.
Summary
For a 2008 Pontiac G6, 5W-30 motor oil is the standard recommendation for both the 2.4L Ecotec and the 3.5L V6. The 2.4L typically takes about 4.5 quarts (with filter), while the 3.5L takes about 5 quarts (with filter). Both conventional and synthetic oils are acceptable as long as they meet API service requirements. Always verify with the owner’s manual and follow the maintenance schedule for best results.