DINO OR SYNTH also viscosity...

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Mar 23, 2003
York, Pa.
on a 91 thunderbird supercoupe - 70k miles - now should I change my oil the first 250 miles or 500?? I have heard both... I put castrol gtx in it I was also thinking about using mobil 1 then. the only advantage of having a aynthetic oil over dino is the breakdown is alot better with synth??? Will dino even breakdown? I know a supercharger will make the engine hotter... One last thing... what is a good viscosity to use? Right now I am putting in 10w30 I probablly shoudll have wen't lighter...
Is this a (set of) question(s) vis'-a-vis' an Auto-rx initial application?
my cousin has the same dang car. All i can say is, #1, at that mileage, make sure your headgasket is good bc my cousins went out around 70,000 and my mercury cougar(1993) went out around 90000. ford made bad headgaskets for those 3.8 engines, so if your temp gauge is going to hot and back, then you got yourself a problem. Other than that, i would run synthetic after an auto-rx treatment or you could just switch over if your not burning any oil. And don't go lower than 10w30 for your engine bc with that supercharger, its gonna tear oil apart easily. Btw, nice car, ive always dreamed of owning one of those.
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