I Own A 3.8L V6 1998 Ford Mustang And Have A Question. I Just Hit 70,000 Miles On The Orignal Motor. I'm Looking To Change To A Full Synth. Oil. Do I Have To Go From A Pure Oil To A Synth. Blend And Then To A Full Sythetic. Or On My Next Oil Change Can I Just Go To A Full Snythetic? And For My Last Question I Currently Put 87 Octane Gas In My Car And The Check Engine Light Came On. The Nice People At Auto Zone Checked Out My Car With Their Comp System And The Verdict Said That My Fuel Was To Weak. Should I Go To The Next Higher Ocatne Or Just Go Stight To The Permium Gas. Really Appericate Any Help Or Suggestions With This Problem.
Tankx

 

Go Full, wont hurt it. Unless you have a tune, or some sweet *** mods you can run 87, maybe cheap gas station, or water in tank. With 70k i suggest you get the "insta dry" just incase, that cant hurt either, and mabey Fuel Injector Cleaner. Then after you put those in, and your on E, Put 1/2-1/4 of premium gas from a GOOD well known station. Try that may be it

 

I call BS on the weak gas! 87 is fine for you if your not tuned for premium
If you wanna spend the extra money on oil, Id say go for it too. That will help your engine last a bit longer. My 98 has 128k on it though, and i just use reguler mobil 10w30