Rearend Chatter after gear oil change

[Bigpaul13]

Hi everyone,

Yesterday I changed the rear diff oil in my 2017 Ram 1500 and started to experience some chatter. I've used Red Line in the past with no additives and it worked great. A local shop started to carry Red Line so I bought the gear oil there not realizing I bought the NS bottles with no additive. I needed my truck today so I just picked up some Mobile 1 gear oil and changed it out. I did some figure eights in a parking lot and everything felt and sounded good.

I notice that I feel the shutter sometimes around corners still but it was good during the figure eight test. Should I try adding in some additional additive? I can get a K&W additive locally today, not sure how that compares to the mopar stuff.

Is there a difference is the additives in the Mobile 1 vs Red Line that could be why I'm having this issue when I didn't have it last time with the correct Red Line oil?

Any advice is appreciated.

 

[Burla]

It probably just isnt enough ls additive in that m1, try adding it and see if it goes away, do 2 ounces at a time, you dont want too much either. If that doesnt fix it if you end up using the hole bottle, consider it as a flush and go back to redline? You have the right weight 140? So you have a LS diff? If you still have the NS redline you can just add NS/LS additive to that.

 

[Dean2]

^^^^^^

What he said.

 

[Bigpaul13]

It probably just isnt enough ls additive in that m1, try adding it and see if it goes away, do 2 ounces at a time, you dont want too much either. If that doesnt fix it if you end up using the hole bottle, consider it a =flush and go back to redline? You have the right weight 140? So you have a LS diff? If you still have the NS redline you can just add NS/LS additive to that.

Thanks Burla. I have the right weight and yea I have the ls diff. I'll pick up the additive today and add it to the mobile 1 in the truck to start. If I dump out the mobile 1 its going to be for the correct red line, not dealing with this again lol.

 

[Burla]

My money is on adding more will fix this, let us know how it works.

 

[Bigpaul13]

My money is on adding more will fix this, let us know how it works.

It seems to be working, thanks! Added roughly 2oz. Had the shutter feeling turning off of my block and then went to a parking lot and did a bunch of full lock turns without issue. Didn't have any issues on the turns on the way home either.

Just another example of how good Red Line is, just don't make my mistake and buy the ns bottles.

 

[jr27236]

Of course if you have a LS rear you need to add the LS additive. I buy the bottle from the local dealer and add it to the the rear and then fill it with the gear oil

 

[Dean2]

Of course if you have a LS rear you need to add the LS additive. I buy the bottle from the local dealer and add it to the the rear and then fill it with the gear oil

Not universally true that you need to add friction modifier. You need to check the bottle your gear oil came in. Some have LSD friction modifier in them already, others have none. Too much friction modifier is not good, just like none or not enough is not good. Friction modifier in an open differential hurts nothing, which is why a number of brands like Red Line include it in all of their Gear oils. Others leave it out as over half of diffs are open and this keeps the cost of the fluid down by leaving out something the majority don't need anyhow.

One approach isn't really any better than the other, just important the buyer knows which version he is buying.

 

[chri5k]

….. Friction modifier in an open differential hurts nothing, which is why a number of brands like Red Line include it in all of their Gear oils. ….

Not universally true. Friction modifier can cause hard shifts in synchro-mesh manual transmissions so Redline makes NS versions of a number of their gear lubes. The OP mentioned he bought the NS version of Redline.

 

[Dean2]

Not universally true. Friction modifier can cause hard shifts in synchro-mesh manual transmissions so Redline makes NS versions of a number of their gear lubes. The OP mentioned he bought the NS version of Redline.

You have to explain to me how Friction Modifier in gear oil in a differential causes hard shifting. That just doesn't track for me. The section of my comment you specifically quoted was very clear, FM in an open DIFFERENTIAL hurts nothing.

However, if you are saying do not use gear oil with friction modifier in a manual transmission, then that makes perfect sense.

 

[Bigpaul13]

You have to explain to me how Friction Modifier in gear oil in a differential causes hard shifting. That just doesn't track for me. The section of my comment you specifically quoted was very clear, FM in an open DIFFERENTIAL hurts nothing.

However, if you are saying do not use gear oil with friction modifier in a manual transmission, then that makes perfect sense.

I think he was pointing out the Redline doesn't include the modifier in all of their gear oils as I found out.

 

[Dean2]

I think he was pointing out the Redline doesn't include the modifier in all of their gear oils as I found out.

Ah ha! Re-read his post a couple more times and now I get that too. That makes perfect sense now.

So re-read what the OP originally posted, and from what I read it was consistent with what I first thought he was saying. He originally used Redline with FM in it, next change ended up with Redline that did not have FM in it, so he changed it to Mobile with FM because he couldn't get Redline with FM and was wondering why he still had a shudder. My guess would be that shudder would eventually have gone away on its own once he got a few more miles on it and the FM had a chance to do its job, now that he had the proper Gear oil with Friction Modifier, but adding a couple of ounces of extra FM won't hurt anything.

Man, this went from simple to convoluted in a hurry, and I am the one to blame for it. Sorry.

 

[Burla]

Just to clarify, the industry "decided" there was "no" harm in modifier being in an open diff. So bottom line all Gear fluids on the shelf already has LS additive in the formula, it is called "universal" gear fluid and you have to look far and wide to find any gear oil without modifier, certainly aren't going to find it on the shelf. Leave it to the OP to buy the one product with no LS additive, lol.

Now, whether the "industry" is right or wrong, whatever, there is NO benefit to having modifier in a manual syncro mesh application. And in fact you will be taking away some of the lubrication for that application because if a quart is 32 ounces and trust me it is, and the added LS additive is 4 ounces trust me it is, then about 12% of the lubrication is non beneficial to that application, where as if you bought NS gear fluid it would be 100% beneficial lubricant. Because gear fluid is the lubrication, the LS additive is not, so the industry says that 12% no big deal, but hey if you have one of those applications why not buy the NS formula, I would.

I say stay away from redline, because once you use it your car or truck is not going to like going back, I have seen it a million times ram forum.

Who knew I would be able to post this twice in one day, to the OP see below...

You big dummy

Fred tells it how it is. Season 1, episode 1 "Crossed Swords".

youtu.be

 

[Burla]

Not universally true. Friction modifier can cause hard shifts in synchro-mesh manual transmissions so Redline makes NS versions of a number of their gear lubes. The OP mentioned he bought the NS version of Redline.

I tend to agree with you over the "industry" anyhow, sad the fall of our institutions.

Found this from Pennrite which tells the difference gl-4 versus gl5 which is modern otc gear oil. The truth is they were lazy and wanted one otc formula for everything, see see this with many things these days. How could 12% less lubrication be perfectly fine if it is not needed? I thought this product from redline was just gl-4 oil, of which I was wrong on that, apparently redline made a gl-5 and somehow kept that spec w/o LS in it.

...

• Contains extreme pressure additives like our 75W90 GL-5 oil, but lacks friction modifiers to balance slipperiness
• Improved copper corrosion protection to prolong synchro life
• Helps with lock-up on weak limited-slip differentials-compatible with Red Line Limited Slip Friction Modifier for tuning slippage
• Also used with clutch-type LSDs in racing for maximum lock up
• Recommended for API GL-5, GL-6, MT-1, MIL-L-2105E and SAE J2360
• Non corrosive formula, safe for use with all synchro materials

 

[1999 White C5 Coupe]

One way to avoid all the guessing and supposition (and to ensure the proper fluid is used) is to purchase and use OEM Mopar fluids specified for the vehicle.

 

[mdc1990zr1]

Ah ha! Re-read his post a couple more times and now I get that too. That makes perfect sense now.

So re-read what the OP originally posted, and from what I read it was consistent with what I first thought he was saying. He originally used Redline with FM in it, next change ended up with Redline that did not have FM in it, so he changed it to Mobile with FM because he couldn't get Redline with FM and was wondering why he still had a shudder. My guess would be that shudder would eventually have gone away on its own once he got a few more miles on it and the FM had a chance to do its job, now that he had the proper Gear oil with Friction Modifier, but adding a couple of ounces of extra FM won't hurt anything.

Man, this went from simple to convoluted in a hurry, and I am the one to blame for it. Sorry.

Maybe the fluid change back to the fluid with the friction modifier in it was not good enough because of the remaining fluid that had NO modifier in it. Adding an once or two of friction modifier to account for the remaining fluid that couldn't be drained may have been the answer. I think it was a friction modifier problem, not a fluid problem.

 

[jr27236]

Not universally true that you need to add friction modifier. You need to check the bottle your gear oil came in. Some have LSD friction modifier in them already, others have none. Too much friction modifier is not good, just like none or not enough is not good. Friction modifier in an open differential hurts nothing, which is why a number of brands like Red Line include it in all of their Gear oils. Others leave it out as over half of diffs are open and this keeps the cost of the fluid down by leaving out something the majority don't need anyhow.

One approach isn't really any better than the other, just important the buyer knows which version he is buying.

Absolutely, I didn't write that accurately where I should have stated that I buy it without the additive. That's what I meant and I buy the modifier from the dealer. They rip you off just to much for the gear oil at the dealer