Proper lube level for a Mag-Hytec cover

[TNRIVERSIDE]

I have recently installed a Mag-Hytec differential cover on my 09 F150. But now I have a technical question that I could use some answers to.
I purchased the aluminum cover to ensure the rear end gears would not overheat and the cover would allow me to change the gear lube with ease. One of the selling points was the larger capacity offered. The advertised capacity was about 5.5 quarts. After installing the cover and filling the cavity to the factory fill level I only used 4 quarts. And the dipstick showed less then the recommended level. I called the manufacturer to be informed that their recommended level is above the factory level. This is one of the reasons that they can increase the capacity to 5.5 quarts. Using their level the lube level is below the axle and above the lower opening to the axle shaft housing. This uses the axle housing to house some of the lube and is said to help with the cooling.
Here is my dilemma. I have learned not to argue with the engineers that designed a gear system. If raising the lube level would help with the cooling and longevity of the gears Ford could have designed this into the differential housing. Also I am concerned that having the ring gear submerged deeper into the lube could increase the friction and foaming of the lube and reduce the lubes ability to cool and properly lube the gears.
For now I am running the lube level at the manufacturers recommended level. This allows me to increase the capacity some and I have an aluminum cover to help cool the lube.
I'm hoping someone has researched this and has a good recommendation.

[Old-Biscuit]

You bought a high capacity differential cover so USE the marks on the supplied dip stick.

Low mark is 'minimum fill'
High mark is 'maximum fill'

Oil level should be in between

[TNRIVERSIDE]

P Kennedy wrote:
If the factory fill level is to the plug opening in the cover you changed how do you know that the level is incorrect. Your drive axle should have some of the oil in it to lube the axle bearings.

I posted this in the technical issue. It is not related to Class A Motorhome.
Sorry.

[P_Kennedy]

If the factory fill level is to the plug opening in the cover you changed how do you know that the level is incorrect. Your drive axle should have some of the oil in it to lube the axle bearings.