Changed my oil today on my 96 GT with about 170k miles on it. And the local autoparts store had a sale on high mileage valvoline synthetic blend. The car has never seen synthetic as long as I have had it. After changing the oil, if the car idles for a while or starts up cold I get some oil smoke from the exhaust for a short time. Is this due to the extra "slippery" synthetic oil slipping past valve seals?
High Mileage and Synthetic Blend
- Thread starter VTGT91
- Start date
fast97gt
Active Member
how many miles are in the car? what your prob seeing is the valve stem seals going bad. its typical with a higher mileage engine. i use and only use motorcraft 5w20 and motocraft filter. walmart normaly cost me $20 oil and filter. you did nothing wrong, its just classic case of a high mile mod motor. even before i swapped the pi engine in my 97, i had over 220k or so HARD miles on mine, and still used motorcrafts 5w20
ChillPhatCat
20+ Year Stangneter 
In short, yes. This could have started because the synthetic does tend to act like a thinner liquid. In my opinion, if you don't start it on synthetic by 100k, don't bother. Conventional "dino" oil tends to run at slightly higher pressure, and that stresses the seals and gaskets in the engine just a little more, sometimes causing micro leaks that synthetic can get through, but not dino oil. In short, your problem might go away if you switch back to dino oil, or it might be here to stay, but it's not a big deal as long as the oil consumption doesn't get bad.
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