Best differential fluid?
- Thread starter leakyfaucet
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DirtyD916
Active Member
i agree royal purple seems to be the best. Atleast 5.0 magazine claims taht it is one of the greatest on the market when they used it on their project car.
Black 93 Fox
Active Member
SuperchargedB87
Founding Member
If youre using the stock cover still, the only way to change it is by taking the cover off. As far as what kind, I agree with the above, Royal Purple is great fluid, but so is Redline and Mobile 1. I use Mobile 1 in mine with no problems and is a little more easier to come across than Royal Purple. And you definately need friction modifier, just make sure you use it in a well ventilated area, because the smell will probably make you sick, it does me at least.
maverick0716
Founding Member
I'm pretty sure that Royal Purple and Redline both have friction modifier already in the mixture.
this is a source of great debate. the synthetics generally say they dont need the modifier. i guess one primary need for the modifier is that is quiets the clutch packs, and synthetics have enough stuff in them to accomplish this.maverick0716 said:
you can read up yourself at redline's site (i use them cuz i can get them in town). they also say how mixing stuff for lsd and the open fluid can change the lock up properties of the diff. (depending upon what you want). i do know of some folks using open diff fluid in their lsd's to make it lock up sooner.
were i you, any name brand synthetic should be fine (personal preference and availability, as mentioned). i would use the modifier if you have any doubts, as it is only 4 bucks at the dealer.
good luck. leave the top couple of bolts loose (but attached) when you pull the cover, so you can pry the lower end off and [attempt to] control the fluid discharge. as mentioned, it is stinky . clean the gasket surfaces real well.
89MustangGX
I have nothing productive to add!
I use and like Mobil-1, and my thinking is unless it says the friction modifier is in there, I would add it.
LXMiker
Founding Member
can someone explain more in detail about the mixing of the synthetic and additive stuff and how it can change whent the clutches lock up......
Michael Yount
Mustang Master
Friction modifier for clutch-type LSD's adds a bit of slipperiness to things so the clutches do their job smoothly. Without it, the clutches can do a grab-release-grab-release dance that results in chatter and noise when making low speed sharp turns that require the clutches to slip. I suppose you could try the synthetics, leave it just a couple of ounces low on fluid, and then add the friction modifier later if it's making racket. If it were me - I'd add it even if you use synthetic. There doesn't seem to be a downside - just be sure the friction modifier and the synthetic are compatible.
I use Amsoil synthetic in mine - seems to work just fine. My limited slip is a Torsen-type which has no clutches, so no friction modifier is needed in it.
I use Amsoil synthetic in mine - seems to work just fine. My limited slip is a Torsen-type which has no clutches, so no friction modifier is needed in it.
right on, and to elaborate...89tang said:
a 3/8" drive ratchet and/or a 3/8 ratchet extension is what you put in the plug to remove it (its a square receptacle). a long extension and ratchet wrench did the trick for me. it is on the driver's side (as mentioned), just above the reinforced part of the pumpkin, just above the half way point of the diff. may need to clean off some grime to see it. (it faces the front of the car).
for draining, loosen and remove all bolts on the outside of the cover, except only loosen (not remove) the top couple bolts. pry the pan off. fluid will come out, but you can control it since the top bolts were left in. then remove them and clean up and reinstall.
messy, but not hard. dont lose the pumpkin id tag (should be on one of the bolts on the top pass side).
a manual is always helpful.
good luck. hope your holidays went well.
Michael Yount
Mustang Master
I thought you had to 1) pull the cover, drain the rear end, 2) cable/pulley the stang's rear end up into the air so the nose of the car was pointing straight down, 3) get on a step ladder and pour in the proper amount of fluid, 4) replace the cover, 5) then lower the car to the ground. Nice that they 'hid' a fill plug somewhere easy to get to. 
Mine has a drain plug at the bottom of the rear end housing, and a fill plug right in the rear cover. Unplug the bottom one to drain; replace; unplug the top one to fill. Not that anyone cares but me....
Mine has a drain plug at the bottom of the rear end housing, and a fill plug right in the rear cover. Unplug the bottom one to drain; replace; unplug the top one to fill. Not that anyone cares but me....
thanks for sharing how much easier things are for you (kinda like when i talk about swapping plugs with my Z28 friends). LOL.Michael Yount said:I thought you had to 1) pull the cover, drain the rear end, 2) cable/pulley the stang's rear end up into the air so the nose of the car was pointing straight down, 3) get on a step ladder and pour in the proper amount of fluid, 4) replace the cover, 5) then lower the car to the ground. Nice that they 'hid' a fill plug somewhere easy to get to.
Mine has a drain plug at the bottom of the rear end housing, and a fill plug right in the rear cover. Unplug the bottom one to drain; replace; unplug the top one to fill. Not that anyone cares but me....
seriously, i often use a long section of fuel line, etc to fill it. (redline, etc. bottles suck for being able to pour fluid in). i run the line along the axle and up over the rear tire. i attach a funnel and hang the funnel from a bungee, as it always takes half an hour to get all the fluid in. LOL).
just did this on the g/f's camaro and it was the ONLY way to go. same for eclipse trans fill. i used non redline fluid on the stang, so i just filled it.
hope everyone's holidays went/are going well!
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