How many quarts of 75W-140 Amsoil do I need for a 04 Cobra with a 8.8 IRS? Do I need a bottle of friction modifier? If so can I use Motorcraft?
BLKSVTCobra01; An 04 Cobra takes 4.2 pints of fluid which equals 2.1 quarts. It will not hurt you to use friction modifier as this will help with any potential chatter. I know when I looked at changing gears in my 03 it was recommended for friction modifier. One four ounce tube of AMSOIL Slip Lock Gear Oil Additive is good for 2 to 4 quarts of gear oil. Motorcraft Friction Modifier can be used with AMSOIL Gear Oil. 75w-140 Severe Gear Oil http://www.amsoil.com/shop/by-product/gear-lube/severe-gear-75w-140/?code=SVOQT-EA Slip Lock Gear Oil Additive http://www.amsoil.com/shop/by-product/gear-lube/slip-lock-gear-oil-additive/?code=ADATB-EA
Let's get the debate going. Amsoil Severe Gere 75W-140 already comes with friction modifier in it, 9 times out of 10 you are fine with just the Gear Oil. If you experience chatter you can add some more, doesn't have to be the Amsoil stuff Motorcraft is fine. Start with half the bottle or tube and see if it goes away, if not the whole bottle should make it go away.
I never knew that this gear oil came with friction modifier in it because when I got my rear rebuilt I gave the mechanic of friction modifer with two quarts of amsoil 75w140 gear oil
I was also unaware of this. Notably, Amsoil's Severe Gear product description states only "AMSOIL Severe Gear is compatible with most limited-slip differentials. If limited-slip differential chatter occurs, add AMSOIL Slip LockĀ® friction modifier additive," while their Slip Lock description states "AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip Lock will eliminate it." It's also interesting that Amsoil's recommendations for my car include the addition of friction modifier. I'm certainly not arguing with you, but can you point us to an authoritative source for your assertion that Severe Gear "comes with friction modifier in it?"
Just the quotes you already have and personal experience with my own vehicles and customers. Amsoil recommends it because the OEM recommends it. Amsoil does not make recommendations to avoid getting sued, among other things, they go with whatever the OEM says. That is why Amsoil also "recommends" 5W-30 for a foxbody Mustang. Like I said you should always pour in the oil take her for a couple figure 8s forward and backwards and see if you get chatter, if not you're good to go. If you do, pour in 2 oz of friction modifier. If chatter continues, pour in the remaining 2 oz bottle.
I would not be willing to skimp on oil for the rear end. I know what you are thinking when you would need to buy three quarts and hardly even use the third quart.
I was wondering because in theory its 2.1 quarts I figured with two quarts and a bottle of friction modifier it would be full. But I'm sure better to be safe then sorry and order three quarts.