Diff fluid capacity

[K4fxd]

Do you fill to the bottom of the fill plug or stop at 2 qts?

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[MiamiGT350]

Correct level is "within 9mm" of the hole. One way to measure is just bend the tip of a zip tie.

 

[WildHorse]

One way to measure is just bend the tip of a zip tie.

I just put a 10mm 90 degree bend a piece of wire . Touches anywhere on it, good to go.
OP: what weight ? I went REDLINE 75w140 full synth w/ 3 ounces of Ford friction modifier.

 

[Cory S]

If I can reach it with my pinky through the fill hole, it gets sent.

oh. I use 75-90W no modifier.

This is what’s in my differential.

 

[K4fxd]

OP: what weight ?

I also use redline 75-140.

I,ve been filling to the bottom of the fill line, 2.5 qts. Should I suck some out?

 

[WildHorse]

I,ve been filling to the bottom of the fill line, 2.5 qts. Should I suck some out?

leave it.

 

[Optimum Performance]

I also use redline 75-140.

I,ve been filling to the bottom of the fill line, 2.5 qts. Should I suck some out?

It only holds 2 qts.

 

[K4fxd]

It took 2.5 qts to the bottom of the fill plug

 

[Optimum Performance]

It took 2.5 qts to the bottom of the fill plug

Was the car level? Should be a few below the fill plug otherwise it aerates the oil and causes a lack of Lubrication problem.

 

[K4fxd]

I wondered if I need to suck some out.

 

[NightmareMoon]

I just put a 10mm 90 degree bend a piece of wire . Touches anywhere on it, good to go.
OP: what weight ? I went REDLINE 75w140 full synth w/ 3 ounces of Ford friction modifier.

I called Redline and the tech said you don’t need the friction modifier with that weight oil. (6MT, 3.73 Torsen)

 

[MiamiGT350]

I wondered if I need to suck some out.

I would draw a little out. I don't think it should be exactly flush with the fill hole.

 

[GTP]

I would draw a little out. I don't think it should be exactly flush with the fill hole.

But a centimeter?

 

[WildHorse]

I called Redline and the tech said you don’t need the friction modifier with that weight oil. (6MT, 3.73 Torsen)

I don't have a Torsen.

 

[Optimum Performance]

A slight overfill causes aeration and lack of lubrication? Any reputable source for this information? I have been in the industry for a long time and never heard of this. I can't imagine 1/2 quart over will hurt anything other than some additional parasitic drag.

OK. When the oil is mostly foam it no longer transfers heat away, it continues to expand and heat and then makes it out the vent in the passenger side wheel well. Over filling differentials leads to no good. Typically fill levels are below the axle centerlines. OEM's spend a lot of energy to determine what is needed and what works. You wouldn't overfill your engine oil for exactly the same reason. Slight overfill is using 2 qts, which is overfilled based on specs. A 1/2 qt in a very small differential housing amounts to something more than slight, its 25% of the total capacity.

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