I have a 2008 Mustang GT with the 3v 4.6L V8. Ford calls for 5w-20 but I’ve read that 5w-30 is the better oil and the move to 5w-20 was only done to improve the mpg standards across the model range. I can’t get a consistent answer and I’m hoping you can put this one to bed for me Scotty.
@jedi391
My understanding is 5w-20 was for fuel efficiency. Also 5w-30 would only be "better" if you are in a hot climate, otherwise one really isn't better than the other if it is a quality oil.
Not likely to matter in older vehicles. The switch to 5W-20 was done without modification to most engines.
Newer engines are likely more tuned to the viscosity (variable valve timing, oil pumps, piston coolers ....).
Scotty does warn to follow manufacturer recommendations for oil though. So don't take my word for it!
