rear diff fluid change

[seabrook]

so putting this out for others i did my rear diff change today at 44k and almost 3 years. i have the 3.92 anti slip. i pulled the plug (14 mm hex) with damn red loctight (i tapped it out) on the passenger side and the fluid came out like honey but stunk a little. the refill was around 2.3/4 quarts. i used royal purple 75/140 full synthetic with friction modifiers. this surprised me - i had a little shudder when leaving my neighborhood but now it’s gone and the truck seems smoother...... yea still shocked. anyway was the fluid bad no but i’m thinking something with factory friction modifiers went bad. also when i pulled the plug it had a light metal coating (looked good) also i think the rear diff had less than 2 quarts from the factory

 

[U&A]

@Burla

RP gear oil (unless things have changed) is one of the worst at protecting your diff.


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[Burla]

I just didnt want to say that, but yeah I wouldn't use that stuff. 4x4 forums and amsoil gear oil study shows it is at bottom of the heap with lucas. RP gear fluids is actually a cus word in some 4x forums, really hits a soar spot for guys who lost gears on the trail. is that fair? Who knows, maybe not, dunno. I mean my buddy asks me to comment, and I cant lie bout it. Some guys like it, and I know some guys who don't for sure, going back 2 decades.

 

[EdGs]

........i pulled the plug (14 mm hex) with damn red loctight (i tapped it out) on the passenger side and the fluid came out like honey but stunk a little. the refill was around 2.3/4 quarts.......also i think the rear diff had less than 2 quarts from the factory

I just have the 3.21 in mine. 107k, and I think that was the factory fill.....smells terrible, but I think thats normal. I think mine had a little less in it too.

Did you strip the plug? Or just ran a tap to clear the loctite? Glad I didn't screw with the drain plug, just dropped the cover.

I was surprised that the cover bolts were american threads instead of metric. I just used a couple studs to line up the cover when I reinstalled it.

 

[U&A]

I just didnt want to say that, but yeah I wouldn't use that stuff. 4x4 forums and amsoil gear oil study shows it is at bottom of the heap with lucas. RP gear fluids is actually a cus word in some 4x forums, really hits a soar spot for guys who lost gears on the trail. is that fair? Who knows, maybe not, dunno. I mean my buddy asks me to comment, and I cant lie bout it. Some guys like it, and I know some guys who don't for sure, going back 2 decades.

Didn’t mean to put you on the spot brother. I just know you have more info on the subject...[emoji1303][emoji1303][emoji1303][emoji41][emoji41]

For what its worth the amsoil test put it real low on the list. (I know you know this Mike, im Just mentioning it)


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[HEMIMANN]

Geez, if it shuddered or chattered, that must by the LP additive, or lack thereof. If you don't want to change again, spike it with some aftermarket LP friction modifier additive. I'd wager that would stop the chattering.

I don't know about RP lubes, but just about anything with oil will work for a while, anyway.

 

[El Huapo]

OK, I'll expose my ignorance here: doesn't the friction additive only work if there's clutches and/or friction discs in there? And do the newer Rams have those? Mine has the Limited Slip but I thought it was a different principle doing the work...? Plus the computer putting in some brake action when needed?
PS: a little squeeze bottle of additive did save my diff on an old '64 Chevy from chattering.

 

[seabrook]

I just have the 3.21 in mine. 107k, and I think that was the factory fill.....smells terrible, but I think thats normal. I think mine had a little less in it too.

Did you strip the plug? Or just ran a tap to clear the loctite? Glad I didn't screw with the drain plug, just dropped the cover.

I was surprised that the cover bolts were american threads instead of metric. I just used a couple studs to line up the cover when I reinstalled it.

lol i meant i had to tap on my wrench, i tapped on it with a pipe wrench

 

[seabrook]

yeah i knew you guys would say that about RP lol we’ll see how it works

 

[seabrook]

Geez, if it shuddered or chattered, that must by the LP additive, or lack thereof. If you don't want to change again, spike it with some aftermarket LP friction modifier additive. I'd wager that would stop the chattering.

I don't know about RP lubes, but just about anything with oil will work for a while, anyway.

that’s what i was thinking but really it was very simple to do so i’ll do it again after 30k miles

 

[seabrook]

OK, I'll expose my ignorance here: doesn't the friction additive only work if there's clutches and/or friction discs in there? And do the newer Rams have those? Mine has the Limited Slip but I thought it was a different principle doing the work...? Plus the computer putting in some brake action when needed?
PS: a little squeeze bottle of additive did save my diff on an old '64 Chevy from chattering.

honestly i don’t know either guess i could look it up. the shudder felt like the transmission was down shifting when i was accelerating from a stop with a turn now it’s a lot smoother.

 

[tidefan1967]

honestly i don’t know either guess i could look it up. the shudder felt like the transmission was down shifting when i was accelerating from a stop with a turn now it’s a lot smoother.

Just out of curiosity, what made you go with RP instead of Redline or Amsoil or the very commonly available Mobil 1? I know that Redline probably has to be ordered but all the other brands should be pretty easy to find at Walmart and from what I've seen whether you buy Supertech or Redline, if its a "synthetic" gear lube they're all within a couple dollars of each other. I had some chatter with the stock fluid also but its gone now since changing over to Redline last month.

 

[seabrook]

Just out of curiosity, what made you go with RP instead of Redline or Amsoil or the very commonly available Mobil 1? I know that Redline probably has to be ordered but all the other brands should be pretty easy to find at Walmart and from what I've seen whether you buy Supertech or Redline, if its a "synthetic" gear lube they're all within a couple dollars of each other. I had some chatter with the stock fluid also but its gone now since changing over to Redline last month.

because it was the most expensive one one at autozone lol... just telling the truth. the RP is full synthetic too i wanted M1 but they didn’t have it. yea i was shocked when my shudder went away

 

[Burla]

because it was the most expensive one one at autozone lol... just telling the truth. the RP is full synthetic too i wanted M1 but they didn’t have it. yea i was shocked when my shudder went away

Just chew on this pdf... Mind you it is random how they set the values and the weight they put on certain items, but you can really tell the bottom oils have some real issues. Your m1 is a good choice, came in second in this test. For next time...

Gears tv did a RP power train test episode on Horse Power tv where they changed everything over to RP and they gained HP, which is more a sign of less protection then it is actual fuel mileage. But for sure RP gains you Horse Power if you change anything over.

 

[Burla]

 

[seabrook]

Just chew on this pdf... Mind you it is random how they set the values and the weight they put on certain items, but you can really tell the bottom oils have some real issues. Your m1 is a good choice, came in second in this test. For next time...

Gears tv did a RP power train test episode on Horse Power tv where they changed everything over to RP and they gained HP, which is more a sign of less protection then it is actual fuel mileage. But for sure RP gains you Horse Power if you change anything over.

pretty cool thanks man

 

[U&A]

OK, I'll expose my ignorance here: doesn't the friction additive only work if there's clutches and/or friction discs in there? And do the newer Rams have those? Mine has the Limited Slip but I thought it was a different principle doing the work...? Plus the computer putting in some brake action when needed?
PS: a little squeeze bottle of additive did save my diff on an old '64 Chevy from chattering.

Yes

The friction modifiers are to increase friction for clutch type LSD’s. If you don’t have clutches it would be beneficial to not use them.


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[HEMIMANN]

What U&A said.

 

[ChevySlayer69]

I thought the modifier was to make the fluid more slippery so the clutch pack doesn't chatter on tight turns, which will increase the life of the LSD.... and the modifier will have no impact on an open differential. So I definitely do not agree with what U&A said.

 

[Burla]

They reduce friction but not like typical EP additives, as in you wont see moly in gear fluids because the stuff is too slippery. Sulfur base, they both reduce friction and grab at the same time. They have determined there is no effect by having FM in open diffs so literally every open out there calls for multi use gear fluid and it is in the gl5 spec, which is for automatic transaxles, older gl's are for manual gear box . You add too much, and you will be changing your diff fluid twice because it will be too slippery, so it will reduce friction. I think both of you had the same point on second point. Sounds like you are both right if that was possible.