For the most part, I'd have to agree that extra additives aren't normally needed in a well maintained motor. But you do run across cars that have been well maintained that end up needing something.
My 96 Grand Prix I feel is a pretty good example of this. It was a dealer demo car for the first year or of it's life. Oil was changed every 3k at the dealership. Then the previous owners to me bought it and changed the oil every 2500-3000 miles with Pennzoil. I don't know how the car was used at the dealership, but for the previous owners, it was a commuter car. All the miles were highway, so the OCI was rather short considering. Then I bought the car with 130k miles on it. Somewhere about 140k miles, after I had been running Mobil 1 changing it every 3k miles as well...I had a lifter get stuck. From everything thats on here, a diet of Pennzoil and Mobil 1 should have really left the engine very clean. And if you looked through the filler cap, it was quite clean looking. Unfortunately, the lifter was still ticking very loudly. Dumped a can of Seafoam in and in a short while that tick turned into a light tap, then was completely gone within a few minutes.
Now I could have tore into the motor and replaced all the lifters...but I figured I'd try this first. Now I'm at 219k miles, and all is well.
My 96 Grand Prix I feel is a pretty good example of this. It was a dealer demo car for the first year or of it's life. Oil was changed every 3k at the dealership. Then the previous owners to me bought it and changed the oil every 2500-3000 miles with Pennzoil. I don't know how the car was used at the dealership, but for the previous owners, it was a commuter car. All the miles were highway, so the OCI was rather short considering. Then I bought the car with 130k miles on it. Somewhere about 140k miles, after I had been running Mobil 1 changing it every 3k miles as well...I had a lifter get stuck. From everything thats on here, a diet of Pennzoil and Mobil 1 should have really left the engine very clean. And if you looked through the filler cap, it was quite clean looking. Unfortunately, the lifter was still ticking very loudly. Dumped a can of Seafoam in and in a short while that tick turned into a light tap, then was completely gone within a few minutes.
Now I could have tore into the motor and replaced all the lifters...but I figured I'd try this first. Now I'm at 219k miles, and all is well.