208k+ mile 2004 Oldsmobile Alero V6 – Just finished major service and it’s running like new (real OBD before/after data + MPG gains)
Hey r/Oldsmobile,
I own a 2004 Oldsmobile Alero 3.4L V6 sedan with 208,000+ miles and it’s still my daily driver in Whitesboro, TX. I just wrapped up a full service package and the difference is night-and-day. Figured I’d share the before/after OBDLink logs and real-world numbers.
Service summary (April 2026):
- April 10 @ Oil Spot: Full synthetic oil + full synthetic Dex-Cool flush/fill
- April 10–12: Iridium plugs + high-performance wires + Techron
- April 20 mobile: Purge valve (P0440), new gas cap, wheel-speed sensor, trans pan drop + synthetic Dexron-VI, new coolant reservoir cap
Key results from April 17 Donut Choice round-trip (~16.2 miles, intentional driving):
- Trip MPG: 29.5 MPG blended
- Cruise: 35–45+ MPG
- Fuel trims: mostly ±2–4 %
- Misfires: Zero
- Temps all rock-steady
The car idles perfectly, feels smoother, and the tank is barely moving. At 208k this thing is a mileage monster.
Anyone else keeping a high-mileage 3400 V6 alive? What’s your next recommended maintenance at this mileage? Tips for LIM gaskets or trans longevity?
Thanks — love seeing these old Aleros still on the road! Here is a I am lovin it run to McDonalds and using the intentional driving of the power band and mpg ...