GF-3 Syn or GF-4 Dino?

[BigAl]

I'm sure most of you are guessing as much as I am, but here goes . . . .

I have a couple of cases of Citgo Supergard Synthetic 5W30 GF-3 oil and a couple of cases of 5W30 Citgo Supergard GF-4 conventional oil in my garage.

Sooooooo . . . which one should I use in my "good" car, the old synthetic or new conventional? (I'll run the other one through my older car.) Assuming an appropriate OCI, which one would really give better protection? Why?

 

[TR3-2001SE]

The synthetic is still the better oil. It may even meet GF-4 after it is tested. It is definitely the better oil even if it didn't meet GF-4 as this rating is a gas milage rating.