All of us know that Ford specs 5W-20 engine oil for the 4.6L modular V8. There are many rumors as to why this happened, as previous generations required 5W-30. Many of those previous generation 2V modulars were also downgraded from a 5W-30 spec to a 5W-20, and nothing internal changed.
So why the spec change? CAFE laws, and no other reason. The 1/16 mpg gain from using a lighter oil (dino versus dino - not dino versus full syn) might be insignificant to you as the end user, but it saved Ford a fortune in fines to the federal government for not meeting the fuel economy mark of 27.5 mpg.
- What is the penalty for not meeting CAFE requirements for any given model year (MY)? The penalty for failing to meet CAFE standards recently increased from $5.00 to $5.50 per tenth of a mile per gallon for each tenth under the target value times the total volume of those vehicles manufactured for a given model year.
Since 1983, manufacturers have paid more than $500 million in civil penalties. Most European manufacturers regularly pay CAFE civil penalties ranging from less than $1 million to more than $20 million annually. Asian and domestic manufacturers have never paid a civil penalty.
- What are CAFE credits? Manufacturers can earn CAFE “credits” to offset deficiencies in their CAFE performances. Specifically, when the average fuel economy of either the passenger car or light truck fleet for a particular model year exceeds the established standard, the manufacturer earns credits. The amount of credit a manufacturer earns is determined by multiplying the tenths of a mile per gallon that the manufacturer exceeded the CAFE standard in that model year by the amount of vehicles they manufactured in that model year. These credits can be applied to any three consecutive model years immediately prior to or subsequent to the model year in which the credits are earned. The credits earned and applied to the model years prior to the model year for which the credits are earned are termed “carry back” credits, while those applied to model years subsequent to the model year in which the credits are earned are known as “carry forward” credits. Failure to exercise carry forward credits within the three years immediately following the year in which they are earned will result in the forfeiture of those credits. Credits cannot be passed between manufacturers or between fleets, e.g., from domestic passenger cars to light trucks.
All Ford modular V8 engines in Australia are spec'd for 5W-30 because they do NOT have CAFE laws in their country. Even the 3V is spec'd the same.
Many posters on here, and other forums, have questioned if a 30W oil would harm the new 3V modular. Some have said, "the variable valve timing is dependent on 20W oil. Do not use a heavier weight or it will not function correctly." I find this to be complete BS....and this is why!
I decided to stray from the 20W spec and take the advice of a trusted peer. Him, and others, began using AMSOIL AZO 0W-30 in their 4.6L modulars with great success. I wanted to share my results and experience with fellow members here, as maybe they would be interested to get more out of their modular.
Let me give a back story....
I was using Mobil 1 5W-20 API SM oil in my Mustang for testing purposes (first 30,000 miles of the engines life). Their reputation was top notch long ago, so you can trust their formulation, right? Most of you know how I truly feel about it, but I needed a popular choice for this comparison. Let's move on to fuel economy and coolant temperature comparisons.
I make frequent trips to see family out of town, and I drive the same direction, same time of night, same speed, etc. With Mobil 1 I always averaged 24.5 MPG (constant speed with cruise control of 80 MPH) on the digital read out (verified to be ~2% off versus manual calculations).
With AMSOIL AZO 0W-30 (5,000 miles of the engines life) the same trip and all other parameters the same I averaged 25.5 MPG. *Please note that time of year and ambient temperature were the same - also verified to be ~2% off versus manual calculations*
*all memory settings were reset for the trip including mpg, odometer, etc.*
Overall I gained 1 MPG @ an average of 80 MPH. *Holding consistent speed for a minimum of 100 miles*
*My car in another test averaged 29.3 MPG
@ 60 MPH with the same conditions*
The next thing I noticed was decreased coolant temperature. I've seen a average of 5* decrease in coolant temperature decrease on my Diablo Predator tuner. I was curious to check the reading when I noticed my in dash temp gauge was reading less than half way. It always read half way until the lubricant change.
So now I know that I actually gained efficiency from a heavier weight oil, but how is that possible you may ask. Allow me to help you understand it better.
- 100% synthetic oil has molecules that are uniform and consistent. Let's do an analogy. Take a pile of rocks that are many different shapes and sizes and let's compare that to a pile of steel marbles of uniform shape. If you were to stir both piles with your hand, which pile do you think would have less friction and was easier to circulate each particle? Of course, the pile of marbles would. They would produce less friction because they glide past each other easier than the rocks would. Less friction means less heat (engine temperature) and more efficiency (higher miles per gallon).
Even though the lubricant weight was increased, the friction of the lubricant was decreased. So not only did I improve efficiency and decreased heat, I also improved the film strength of the lubricant with improved shearing stability. This means overall better protection for my engine which will assure me of a very long life.
Want to know more about the oil of choice for year round use my Mustang? AMSOIL evens recommends it for our cars.
AMSOIL AZO 0W-30
For summer aggressive driven cars, and supercharged engines, I prefer this
Amsoil ATM 10W-30
Read this thread to understand why 10W-30 is preferred. Read post #30 and #31
Team Shelby - Why 10W-30
Just looking out for my fellow Mustang owners.
*Post edited due to Amsoil renaming their 0W-30 to "AZO", and wanted to eliminate any confusion*