I bought a 4WD 09 FEH a couple of weeks ago and have read both the FAQ on this board and the owners manual and they both say it takes 2,000 - 3,000 miles of "break in" before the gas economy improves. Why is that? Does the hybrid software have to build up some history before you get better fuel economy?

I was thinking about using Mobil-1 synthetic oil instead of the synthetic blend that Ford recommends - any pro/cons on this?

 

Many owners including myself use Mobil 1. I have even had two different Ford dealerships use the Mobil 1 oil I gave them to install during service work.

 

I'm a beiever in Mobil One. There are a few others (Red Line, Amsoil) that are 100% synthetic. I believe the rest are dino oil base stock with a synthetic package added. Understand that the friction characteristic is determined by the bulk oil not the package. Look up the MSDS of the oil you're thinking of, if it mentioned parafins and such its dino oil base (they can't get around this in their MSDS).

I believe the "break-in" occurs in the first few tens of hours with the greatest amount of break in within the first hour of run time. Unlike the "old days" when machining was not nearly so good and parts really did have to wear together, these days the manufacturing part tolerances are so good that the break in occurs very, very quickly.

I have an 01 Mustang Cobra that I put on Mobil One at 8 miles, its now at 250,000 miles and I still get 6,000 miles per quart. I put my FEH on Mobil One at 78 miles.

Do it!

 

I believe the break-in occurs as much in the operator of the vehicle as in the vehicle itself over this period. There are learned behaviors involved in the driving that will maximize the FE numbers.

 

Well, your Owner's Guide says on page 5 "Your vehicle does not need an extensive break-in. Try not to drive continuously at the same speed for the first 1,000 miles of new vehicle operation. Vary your speed frequently in order to give the moving parts a chance to break in."

Your Owner's Guide does not say that it takes 2,000 - 3,000 miles of "break in" before the gas economy improves. Rather, on page 292 it says:
" We do not recommend taking fuel economy measurements during the first 1,000 miles of driving (engine break-in period). You will get a more accurate measurement after 2,000 - 3,000 miles." And then it goes on for two pages describing how you will realize more accurate fuel economy measurements over a longer period of time, driving conditions, temperatures, driving habits, and so on. That I think is why they recommend that mpg caculations will be more accurate after many more miles.

 

No full synthetic for 1000 miles to permit the rings to seat. Vary speed to prevent narrow wear patterns on gears. If you live in below freezing environments, go to 0w20 to reduce wear on start-up. Motorcraft has a full synthetic oil (5w20). Motorcraft semi-synthetic 5w20 is fine for 95% of us. Full synthetic is ok, just not necessary unless you need extra protection at start-up. Change your oil and filter at the recommended interval or sooner.

 

I disagree.

Some years ago I had to replace the rear axle on my Suburban (don't ask, it's a son in college kind of thing). I discovered that the break in for the axle was identical with the break in for the car.

I did some home work as this piqued my curiosity. The recommended break in is for the differential(s) as the alignment of the gear teeth and the fine particles in the axle can wreak havoc if they are not allowed to wear together.

I believe the ring seating thing was probably true 50 years ago but is no longer an issue. Today there are many stories and tales of why we "break" in cars but when I researched the axle issue I found that it dominated the field by far.

There are a number of cars that come factory direct with Mobil One already in the engine.

 

While there are cars that come with Mobil 1 I wonder if these engines are set up differently then the run of the mill ICE. Typically ICE's with Mobil 1 are in high performance engines like in the Corvette. I have to think that these engines are built to different specs as performance requires tighter tolerances and much more detailed assembly techniques. To say nothing of the higher quality parts used as well.

I would tend to side with a more conservative option. Run the factory oil for 1-3K and then replace with high quality full synthetic. If one wants to take full advantage of these syn oils then add a by pass oil filter and do some used oil analysis and extend your oil change intervals to when the oil actually needs to be changed as the oil testing will dictate.

This is what I do in my 6.0L Ford diesel. I run it out to 20K per oil change with better and cleaner oil thanks to excellent Schaffers 9000 5w40 and the Oilguard by pass oil filter. It may last out to 30,000 miles per change testing will confirm this.

Factory full flow oil filters, filter out particles down to 20-25 microns. By pass Oilguard filters get particles down to about 1-1.5 microns. This is as clean as new oil. I know I have the test results to back this up. Oil this clean will not damage anything in the ICE. Long haul truckers have been doing this for decades with excellent results.

 

Engine cylinders and rings designed to operate on full synthetic factory fill oil are machined, honed and mated differently than ours. If you introduce a full synthetic oil before the rings have seated, you can glaze the cylinder walls and the rings can become barrell shaped. This can lead to a loss of compression and oil blow-by.

Not sure what Bill Winney disagrees with. There are a lot of gears, rotating assemblies and mating surfaces to break-in beyond axle gears. I'll go with what the Ford Engine and Powertrain Engineering Groups recommend.

 

I disagree with the statement that engines need the break in stated in these posts.

My point about the axle break in is that that is what the Ford books (& Engineers) are breaking in, not the engine. They don't identify what the break in is for and based on my experience I believe it is for the axle not the engine.

I have Oilguard bypass filters and an electric prelube pump on my Mustang & Suburban . I have been sampling oil on the Mustang all along the way & the Suburban since putting in the bypass filter. I have put a bypass filter on the FEH and am considering whether to use a prelube pump or an accumulator to keep it lubed while running.

The longest interval I've gone on the Mustang is 33,000 miles between oil changes. I had formed the opinion that I would let the oil samples tell me when to change oil. Well, they never did, and 33,000 was as far as I was willing to go.

On my Mustang I put in Mobil One at 8 miles and saw little change in sample numbers along the way. Back in 92 when I bought the Suburban I waited and put in Mobil One at about 5,000 miles. After the years with it, I concluded that waiting for the break in was un-necessary (currently at 383,000 & gets 5,000 m/qt). (There are those that would say that at 383,000 the Chevrolet 350 cu in V-8 is still just barely broken in!)

If you read the Mobil One info they say it can be used from the start without any break in period. I agree.

I have been involved in Engineering on Navy Ships for 30 years and understand what they do for diesel engine lube oil monitoring. It is quite similar.

I believe that crediting standard full flow filters with 20-25µ filtration is optimistic. My research says that it is more like 30-40µ.

I have also installed Canton Racing Products 8µ full flow filters on my cars. I did this on the Mustang at about 100,000 miles and saw a 2-3% improvement in fuel consumption numbers. I didn't recognize this last until I had about 30,000 miles under my belt from the installation and saw it in the plots I keep.