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Discussion Starter #1
I just flipped 1200 miles on the R/T today and decided to change the rear gear goo. 3 bottles of RedLine 75W90 standing by. Drained 30ozs out. Really? It took 48ozs until fluid ran out of the fill hole. Low again from the factory and even after the "great" dealer PDI. I can't believe how little oil is in these differentials. But only 48ozs, I'll change it every year.
 

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2018 Dodge Challenger T/A Plus in Yellow Jacket w/5.7L and A8 automatic
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That is indeed scary. I guess I should put checking the fluid on the “to do” list tomorrow. Ironically......I buy my Castrol GL5 75w90 by the five gallon pail. My 2018 RAM 4500 holds 5.5 quarts in the front differential and 7.5 quarts in the rear differential. Changing both will use about 65% of a five gallon pail.
 

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Discussion Starter #6
White R/T, That's what it took to run out the fill hole. Can't help it. I guess I could've not added it right. 1 bottle + 16oz's...………...…..
 

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You're good, that's how all diffs are filled, you fill it to the top hole. The factory uses a set number like that because it's automated and close enough.


Sent from my SM-N960U using Tapatalk
 

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2018 Scat Pack SHAKER in Plum Crazy
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Ignoring the difference from what you drained to what you put in. You can't compare the amount of fluid to old school rear ends. There is no axle tubes to hold fluid so it is a much smaller area now. And cooling isn't as much of an issue since they are all aluminum, and the HP ones are finned.
 

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Discussion Starter #9
Pioneer4X4, Ya I hear ya. It just seems like 1.25qts is not much oil. OTOH...….I can now change it every year. The factory oil came out smelling like gear oil(good) but was really dark. But not knowing what color it was to start with.....who knows??? RedLine 75W90 in it now, a nice golden light tea color now.
 

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2018 Dodge Challenger T/A Plus in Yellow Jacket w/5.7L and A8 automatic
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Pioneer4X4, Ya I hear ya. It just seems like 1.25qts is not much oil. OTOH...….I can now change it every year. The factory oil came out smelling like gear oil(good) but was really dark. But not knowing what color it was to start with.....who knows??? RedLine 75W90 in it now, a nice golden light tea color now.
Most all initial differential fluid changes are darker in nature, perhaps due to some of the assembly oil they use as well as everything is typically “tight” until it gets burnished in properly. The first few heat cycles are typically going to create more heat than when broken in, so some of the dark fluid color is due to some initial heat cycling as well.
 

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2014 SRT 8
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Most all initial differential fluid changes are darker in nature, perhaps due to some of the assembly oil they use as well as everything is typically “tight” until it gets burnished in properly. The first few heat cycles are typically going to create more heat than when broken in, so some of the dark fluid color is due to some initial heat cycling as well.
Depends on the limited slip, Ford uses carbon fiber disc's, hence the color of fluid
 

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Ignoring the difference from what you drained to what you put in. You can't compare the amount of fluid to old school rear ends. There is no axle tubes to hold fluid so it is a much smaller area now. And cooling isn't as much of an issue since they are all aluminum, and the HP ones are finned.
So what should be the way to fill? Till it's below the fill hole? Is there a shop manual that tells how much to use?

My owners manual only tells me to inspect every 30,000. But no interval when to change unless used for police, taxi, fleet
or frequent trailer towing.

Recommended oil is MOPAR® OD Synthetic Gear Lubricant SAE 75W85 (API GL-5)

I'd like to change mine soon, but don't want to overfill if it doesn't need it.
 

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Discussion Starter #13
So what should be the way to fill? Till it's below the fill hole? Is there a shop manual that tells how much to use?

My owners manual only tells me to inspect every 30,000. But no interval when to change unless used for police, taxi, fleet
or frequent trailer towing.

Recommended oil is MOPAR® OD Synthetic Gear Lubricant SAE 75W85 (API GL-5)

I'd like to change mine soon, but don't want to overfill if it doesn't need it.
Put the fluid in until it runs/seeps/dribbles out of the fill hole. Install fill plug......Done.
 

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Thanks
 

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2019 Hellcat Red Eye Widebody
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All,

I read a post about Royal Purple differential fluid - the 75W-90 with the friction modifier additive - and how it quieted the characteristic differential "whine" that Challengers often experience. I noticed this right away in my 2019 Hellcat Red Eye when I was going about 40-45 mph and let up on the gas. Wasn't terrible, but noticeable. As an aside, when I was 16 and looking for a used car somebody told me unscrupulous people would put sawdust in their differentials to quiet worn gears. I decided to change my fluid at 1,738 miles on the odometer - cheap enough, might quiet the whine a bit, supposedly excellent fluid attested by many here, and I thought I read something in the HPDE literature about changing differential fluid after a couple of days of hard driving.

So I got a cheap siphon pump thinking for some unknown reason (as I write this the idea seems stupid) that it would be a good idea to drain the fluid from the top hole, and a cheap fluid pump with which to pump in the new fluid ( good idea for something in a bottle, but not required with a squeeze bag like I saw with an AMSOIL product), got an 8 mm hex thingamabob for my ratchet and set to work! I "got 'er done", and am particularly proud of the way I did this so cleanly and neatly. Elegantly...is a word that comes to mind.

Not!

But I had fun doing it and learned the bottle needs to be secured, and the hose needs to be held inside the bottle. I needed a helper - or at least a third long arm!

Best,

Finface (whose Hobby Mechanic Third Class certification quest remains questionable...)
 

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I'm going with Redline 75W85
 

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Discussion Starter #17
All,

I read a post about Royal Purple differential fluid - the 75W-90 with the friction modifier additive - and how it quieted the characteristic differential "whine" that Challengers often experience. I noticed this right away in my 2019 Hellcat Red Eye when I was going about 40-45 mph and let up on the gas. Wasn't terrible, but noticeable. As an aside, when I was 16 and looking for a used car somebody told me unscrupulous people would put sawdust in their differentials to quiet worn gears. I decided to change my fluid at 1,738 miles on the odometer - cheap enough, might quiet the whine a bit, supposedly excellent fluid attested by many here, and I thought I read something in the HPDE literature about changing differential fluid after a couple of days of hard driving.

So I got a cheap siphon pump thinking for some unknown reason (as I write this the idea seems stupid) that it would be a good idea to drain the fluid from the top hole, and a cheap fluid pump with which to pump in the new fluid ( good idea for something in a bottle, but not required with a squeeze bag like I saw with an AMSOIL product), got an 8 mm hex thingamabob for my ratchet and set to work! I "got 'er done", and am particularly proud of the way I did this so cleanly and neatly. Elegantly...is a word that comes to mind.

Not!

But I had fun doing it and learned the bottle needs to be secured, and the hose needs to be held inside the bottle. I needed a helper - or at least a third long arm!

Best,

Finface (whose Hobby Mechanic Third Class certification quest remains questionable...)
Did it help the whine out???
 
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