5w-30 Motor Oil If You Live In Australia, And 5w-20 If You Live In The US...

[Pushrod2Mod]

So we are told by Ford to use 5w-20 oil in our Mustangs due to tighter engine clearances in the 4.6 engine. In 2001 Ford began recommending this despite there being no change in engine clearances from the previous 4.6 engines. I have then heard from people in Australia claiming that their owners manuals recommend 5w-30 despite Fords claim of tighter clearances. So I then proceeded to visit a few online auto parts stores based in Australia allowing me to search for items sold for my car ( 2007 Ford Mustang GT 4.6/3v), and what are the oils recommended for my car? Well three choices come up- 5w-30, 5w-40, and 10w-40.

Then we have notable modular engine builders and also ex-Ford engineers suggesting no oils lower than 5w-30 should be run in our Mustangs. It is clear to me that The Corporate Average Fuel Economy (CAFE) standards has Ford recommending a lesser weight oil than the 5w-30 oil our engines were originally designed for in the first place. Either weight of oil will last the 36,000 warranty period, so its no lose for Ford. I just find it truly disgusting that a lesser quality of oil is recommended to customers over a small cost savings from CAFE regulations. I just wonder how many additional miles one could get out of their 4.6 by running the correct oil weight during the lifetime of their car.

I have read enough to convince me to run 5w-30 for now on. Has anyone else researched into this?

 

[Bullitt95]

Ford recommends 5W-20 and it even says so on the oil filler cap, so that's what I run.
Currently using Castrol Magnatec full synthetic.

 

[Pushrod2Mod]

What do you think about the info I posted? Do you find it odd that 05-09 Mustang GT's in Australia recommend 5w-30 in their Ford Owners Manual despite Ford's claims of tight engine clearances to us in America? Or that identical motors in previous years to 2001 used 5w-30 despite Ford claiming tighter engine tolerances in 2001+ identical engines which require 5w-20 oil? Or that Modular professionals and ex-Ford 4.6 engineers claim using anything under 5w-30 is a very bad decision in our engines? And then top it off with fines from CAFE regulations for Ford if they dont find a way to get better MPG in which no doubt Ford used a thinner oil to achieve all at our expense?

Do you find any of this suspect or not?

 

[racerraj]

I've been thinking about switching to 5w30 for a while. I have an oil change just about due and I'm likely to give it a try. I always run Mobil 1, so I think I would have good protection with 5w20 or 5w30. Just seems like traffic in the summer 5w30 would be better. My car has 273,000 miles all with Mobil 1. Even though it is Mobil 1, I'd bet I have slightly more clearances than I did new...LOL! I've lost three rockers on the passenger side, I kinda wonder if 5w30 might help reduce that.

 

[Bullitt95]

The 5W-30 will have a slightly higher viscosity when hot do it would be a good choice on a high mileage engine, or if you live in a place that experiences extremely hot summers.