I just purchased a '91 Ranger with a 3.0L. The truck has 93K and I am the third owner. The vehicle was purchased by the second owner at 48K and had conventional oil run in it until that time and until about 60K with the second owner.

At that time the previous owner went to Mobil 1 Synthetic. If I switch back to conventional oil will it do any damage? I've heard that if you switch from synthetic back to conventional it can do something to the seals and possibly damage them? I don't know, I really don't want to run synthetic in it because of the price.

Let me know what you think.

 

No problem going back to conventional "dino" oil. Your truck will be fine.

 

Just keep it changed (along with filters) at regular intervals.