what grade oil
 

What oil used in a 97GT
I don't have a owners manual

The manual says to use Motorcraft 5W30. I use Valvoline Synthetic 10W30 in mine since its so hot and humid here in VA. Its a matter of opinion what weight or brand oil you want to use. I always thought the 5W oil was kinda thin.

Depends on where you live and what type of climate you drive in.
5W30 or 10W30 is pretty safe though. I would think 5W30 should be used for a little cooler area's.

It should also be shown on the emission sticker under the hood. I agree with the others, 5-30 is awfully skinny unless it's pretty cold.

oil
 

I have a 2001 gt and I use 10w-30 motorcraft premium. The manual says to use 5w, but I think that it is a little on the thin side myself.

I've heard that in the mod motors the clearances are tighter and that is why they call for the thin stuff.

I use 0w30 in mine

I use 5w 20 just as the owners manual recommends.... Is this grade ok??? I live in Southern California where it doesnt get extremely cold.

Yep, if I could buy 5w20 in mobil 1 synthetic I would be using it. If your putting some .99 cent oil in the engine then maybe you should worry, but if its a good grade oil then I can't see where theres a problem