Which gear oil?

[HEYBOSS]

Here we go again but as you all know, there's no search.



I've got 22k on rear end, 4. 10 Lsd.



which one would you go with and why.

I don't race, truck is stock for now and tow 12k trailer about 5 thousand miles or so a year.



not necessarily in order.



1. Amsoil 75w-140



2. Mopar 75w-140



3. Red line 80w-140



4. Royal purple 80w-140



Red line and Royal purple I can get it local, both about $8. 00 qt.

Amsoil is a little more and also available local

Mopar is the most expensive at about $16. 00 qt.



I'm not concerned with the price, just would like to know which one is better. What is the Mopar stuff? is it Valvoline?



TIA, Fred.

 

[John]

Personally, I would go with your first selection HOWEVER, ALL of your choices are EXCELLENT ones.



My preference:



1) Amsoil Series 2000 75W-140



2) Red Line 75W-140NS (WITH THE APPROPRIATE AMOUNT OF FRICTION MODIFIER... as this product has NONE!)



3) Red Line 85W-140



4) Royal Purple 80W-140 (or is it 75W or 85W?)



5) NEO Synthetic equivalent to above



6) Mopar 75W-140 ($ )

 

[24V-DSL]

John....

What did you put in your new Dana 60?



How much did it take?



TIA... Joe

 

[RustyJC]

We tow a 13,500 lb GVWR 5ver and use Royal Purple 85W-140 which has the LSD friction modifier already formulated into it. It worked great for us right out of the bottle - no supplemental Mopar friction modifier required. 3 quarts overfilled our Dana 80 with the stock cover by about 1/4".



Rusty

 

[John]

Joe (24V-DSL), I switched from Amsoil's Series 2000 75W-90 to their Series 2000 75W-140 in my front differential when I installed my new Mag-Hytec diff. cover.



After very accurately tracking fuel mileage while using 75W-90 in the rear differential and then switching to 75W-140... I ascertained there was virtually NO difference hence, my decision to go with the 75W-140 up front too.



If I lived where it gets colder in the winter you can bet I would reassess my approach.

 

[24V-DSL]

John....

Thanks...



Still like to know how much you put in the Mag-hytec.

 

[John]

Joe, sorry about missing the quantity...



Mag-Hytec states the front diff. (Dana 60) will take about 4 qts. with their new diff. cover however, I found that mine took a little over 4 qts.



BTW, the Mag-Hytec dipstick is ONLY accurate if you have a Ram that has NOT had the axle rotated as is the case with a lift kit etc.

 

[Wheaties]

Fred,



It's a good question. I'm thinking about changing my fluids out soon also. So do synthetics affect the performance of the limited slip? If so how? I'm pretty sure there was a thread on this a while back, but who can find it?



I'd be inclined to go with a good quality synthetic for the higher quality lubrication, and better long term stability, just so long as it doesn't interfere with the limited slip. After that, I'd say it's brand name loyalty.



Matt

 

[John]

Matt, the high dollar Mopar 75W-140 gear oil is 100% synthetic.



Some synthetic gear oils like the Amsoil Series 2000 75W-90 have enough friction modifier for the OE LSD however, others require that you "tune" the LSD characteristics via adding more friction modifier. Other synthetic gear oils (namely, Red Line 75W-140NS... NS = No Spin is for special applications) have NO friction modifier, and as such, HAVE TO have at least two bottles of friction modifier added prior to driving your LSD equipped Ram. Red Line's recommendation is to use their 75W-90 synthetic or if you prefer a heavier multi-viscosity gear oil, their 85W-140 synthetic which may have enough friction modifier for most LSDs. Sorry, I don't have any first hand experience with the Royal Purple 80W-140 gear oil although, I have heard it is an excellent product!

 

[HEYBOSS]

Correction

The red line I can't get it local, I have to order it from Summit Racing. The others I can.



John, I guess that leaves out red line since there's no modifier in it and it's not local, I rather use one that already has the modifier if I can but it's not a big deal anyway.

So it's a toss up between the others. You mentioned that Mopar is 100% synthetic so maybe no modifier needed?



Does anyone know if Royal Purple is 100% synthetic?



And John you're right the Royal is 85w, my mistake.



I'm leaning towards the Mopar or Royal, one reason being local.



Also that Mopar price is at a discount, it actually list for about $19. 00 per qt.

 

[HEYBOSS]

Matt

I really don't know how much if any synthetics affect the performance of the LSD but it is a much better gear lube. I just like to change it because I do some towing and the manual recommends it. I'm sure synthetics are much better than conventional fluids, to me it doesn't justify it on engine but to each it's own.

 

[Wheaties]

Fred,



Sounds like you're way ahead of me, as I'm sure you'd be. Thanks for bringing me up to speed.



I think that the last time I read a thread about this, someone suggested that some synthetics were so slippery, that no friction modifier was neccessary. Whether they're really slippery enough not to need modifier or come with modifier already in them doesn't matter much I guess.



Beyond that, unless you know that a given oil has the right amount of friction modifier, what are you going to do if it has too much modifier? I mean, to little modifier is easy, just add some. Too much however, and you can't take it back out. You'd have to drop the oil and put something else in. Guess you should ask on the TDR!



Any consideration for Mobil-1 gear oil?



Matt

 

[LSMITH]

You can get the Mobil 1 75W-90 racing gear oil anywhere you happen to be and it is cheaper than the ones you mention. It is a full synthetic. The LSD in my truck is extremely tight, and I needed the friction modifier with the Mobil 1. I saw a 30 degree plus drop in diff temps when I switched, I have it in both diffs and gained 1 MPG + by using it in the winter months. Look to pay about $6. 00 a quart for it.

 

[HEYBOSS]

Matt

You bring up a good point, really never thought about a given oil having to much modifier, I guess someone can chime in here and let us know. I think I've also read in the past in here that Royal Purple already has the modifier in it.

I called two different local dealers today and guess what the answer was? Yeah you guessed it, both have different answers, one said no modifier needed with their synthetic and the other said yes, they don't even know



RustyJC_ I read your post too fast and didn't notice you noting that the Royal Purple has the modifier in it



It seems like I'm drawing a conclusion that some LSD's are tighter than others from factory and that some may need the modifier more than others, am I right? Can anyone elaborate on that?

 

[HEYBOSS]

One other issue to consider is if anyone using any other gear oil other than Mopar could it be a problem in the future on a warranty issue if the problem was ever to rise? may be or may be not. I would think that if you're using gear oil that is compatible to oem or meets it's specs you would be OK. It's like using different engine oils but you know dealers if they can pick on something to void a warranty claim they would. So if I used their "recommended $$$$Mopar" gear oil then it should be no problem on a warranty claim.



Fred.

 

[Wheaties]

Fred,



If you have any doubts at all, go with the Mopar and don't let anyone tell you otherwise. I think you're right, that any oil that meets the spec is acceptable for the rear differential. If it were the manual transmission, I'd go the other way and say I'd never use anything but the unique oil that my transmission (NV5600) seems to be designed around. Not so the engine or the diffs, I think any appropriate oil will do.



Is it a grey area? It might be. Depending who you talk to, you can put any oil filter you want on your engine. Others will tell you that you have to use the Mopar filter. Somewhere in between, there's a list of known 'bad' filters that claim to meet the spec.



I looked over on dodgeram.org (Dave Fritz's website) and didn't find a lot of info... maybe I'll look again.



Matt

 

[HEYBOSS]

Matt, I appreciate the input. My point here to is... . I've ran across many times it the automotive business that some after market products are better than OEM and sometimes at a lower price and vise versa. That is one of my points here, if an after market gear oil is superior than OEM and the price better, why not.

But like I mentioned before, to me price is not a matter.



Fred.

 

[HEYBOSS]

Originally posted by RustyJC

We tow a 13,500 lb GVWR 5ver and use Royal Purple 85W-140 which has the LSD friction modifier already formulated into it. It worked great for us right out of the bottle - no supplemental Mopar friction modifier required. 3 quarts overfilled our Dana 80 with the stock cover by about 1/4".



Rusty

You could have a problem with leaky seals due to overfill.

I believe they recommend 1/4" below the fill hole.

 

[Wheaties]

I'm with you Fred! I'll put anything in my truck, but I have to know it's the best thing for it.



I'm kind of wondering where the experts are. Any one out there really know what's the best for your pumpkin?

 

[BigDaddy]

When it was time to change the powertrain fluids I had three things in mind:

Proven compatibility/reliability

One stop source

Most bang for the buck



AMSOIL met this criteria and then some. A point to note: I am very skeptical about improved fuel economy claims (in regards to lubricants), but surprisingly, I saw a gain of . 5 Mpg’s with AMSOIL Not to mention extended drain interval.



AMSOIL Series 2000 75W-90 Gear Lube in the front and rear and AMSOIL Universal Automatic Transmission Fluid in the auto and transfer case.



You can get great prices on AMSOIL through the Group Purchase Site. When you get there just click on the AMSOIL Logo.