my 04 gt calls for 5-20 oil and everyone seems to tell me to use a fully synthetic, 5-30 synthetic is easy to find and 5-20 id have to order online if i wanted to use a fully synthetic but is it really that much better? whats the big difference and why wouldnt ford just say use synthetic if its better for your engine? any thoughts? thanks guys.

 

cause ford recomends using their motorcraft oil. they say if you dont use it, it can void your warranty.which i think is stupid.

 

5-30 synthetic is perfectly fine, just use that.

 

yeah just use that. you'll be fine. thats what i used in my 2000 GT.

 

synthetic is alwyas better. i LOVE Amsoil!

 

i run redline 5w-20 synthetic oil.

 

oil is a bunch of hype. I use Mobil oil, just because it's the cheapest. OIL IS OIL!

 

My builder told me to use Valvoline 20w50 synthetic, but my motor is somewhat modified.

I ran Mobile1 5w30 before the engine build. Seemed fine.

 

Yeah just use the 5w-30 it will be fine, i use castrol syntex 5w-30 in my 01' GT, and have been running castrol syntex for the last 12 years and have had no problems with it. just my .02

 

10W30 Royal Purple full synthetic here. Don't run anything but synthetic oil. Great stuff: virtually no engine wear or formation of sludge, increased fuel mileage, increased HP and rpms, increased drain intervals, much easier starting in cold weather (pours at -49 degrees or lower) and higher film strength! Anymore questions? Royal Purple, Amsoil, Redline, Mobile 1, take your pick. ANY synthetic is better than a conventional oil.