75W-90 Synthetic WITHOUT Limited Slip Additive - Mobil Delvac?

[Spddm0n]

So, I am changing the rear axle oil in my 2003 Dodge Ram 2500. It has a Limited Slip differential in it (helical type), and generally, it's understood that no friction modified or LSD additive is necessary. Also the Dodge user manual (with poor punctuation) appears to say, NOT to use any Limited Slip Additive, but to use a Synthetic gear oil. Ok, fine, but it appears there are very few 75W-90 Synthetic gear oils that are available for a "normal" price (less than $30/gallon). I have not subscribed to the typical "higher grade" oils, like Redline and Amsoil for +$20/quart. It's hard to accept that in a differential (with an aftermarket diff cover) that requires 8 quarts to fill it.

So, I landed on Mobil Delvac 1. I'm not experienced with most of the Mobil 1 lineup, so I wasn't shocked by my confusion when I found the marketing between USA and other European markets (including the United Kingdom) different, in regards to publishing about "Limited Slip". The USA marketing suggests NOTHING about Limited Slip and Summit Racing website says "NO", in relation to the Limited Slip Additive.

The United Kingdom and European markets say "limited slip gear lubricant"...but I can't confirm the product part numbers are the same, so perhaps they are actually different fluids.

Anyone know what is going on here?

 

[OLEJOE]

I bought a case of it from Summit and it does not have the LS additive in it. That’s what I ran in my 18’ and it is what will go in my 22’.

 

[OLEJOE]

Mobil does sell fluid with the LS additive but I’ve only seen it in quarts.

 

[65f100]

Summit sells it cheaper by the quart.
https://www.summitracing.com/parts/mob-122044-1

 

[edyvw]

That is the most popular product among Porsche crowd.

 

[OLEJOE]

Summit sells it cheaper by the quart.
https://www.summitracing.com/parts/mob-122044-1

That’s cheap than Super Tech. You have to buy $100 to get free shipping I believe.

 

[D60]

Interesting, is there reason to believe the additive is actually causing issues? My understanding was that it's one of those things that can only help, or do nothing.

And I agree -- it is difficult to find 75-90W without it, but I typically prefer that because it's just "one less thing" as Forrest Gump said

 

[Spddm0n]

I bought a case of it from Summit and it does not have the LS additive in it. That’s what I ran in my 18’ and it is what will go in my 22’.

Gotcha. Do the later model Ram trucks still have the AAM axles in them?

 

[Spddm0n]

Mobil does sell fluid with the LS additive but I’ve only seen it in quarts.

Yeah, those seem to be plentiful. The version without LSD additive is tougher to find.

 

[Spddm0n]

I a

Summit sells it cheaper by the quart.
https://www.summitracing.com/parts/mob-122044-1

Holy wow! Weird. This is the first time I've seen that happen, anywhere. Thanks for pointing this out! It does look like it's out of stock for a few weeks though. .

 

[4WD]

I have used Delvac 1 in GM G80 lockers for many years

 

[Spddm0n]

That is the most popular product among Porsche crowd.

Interesting. I was trying to figure out how this whole line of "Delvac" products differs from the typical Mobil 1 products. I wonder if the base oil and pressure package is the same for the 75W-90 with the LSD additive (personal vehicles) and the Delvac 75W-90 (commercial product line?).

 

[Spddm0n]

I have used Delvac 1 in GM G80 lockers for many years

Thanks for the comment. Are those an LSD, or a full on-demand locker?

 

[Spddm0n]

Interesting, is there reason to believe the additive is actually causing issues? My understanding was that it's one of those things that can only help, or do nothing.

And I agree -- it is difficult to find 75-90W without it, but I typically prefer that because it's just "one less thing" as Forrest Gump said

Well, I was reading notes from a company called Torsen, that makes a helical LSD, that the LSD additive does affect the "torque" bias and will cause the differential to behave more "open", when it should be locked. I don't know how these AAM 11.5" helical LSD axles behave without any friction modifier, but I wanted to start with NO additive, and then add some as necessary for me. I want to have the best LSD performance I can, without chatter on the street during turns.

 

[edyvw]

Interesting. I was trying to figure out how this whole line of "Delvac" products differs from the typical Mobil 1 products. I wonder if the base oil and pressure package is the same for the 75W-90 with the LSD additive (personal vehicles) and the Delvac 75W-90 (commercial product line?).

They like it in manual transmissions.

 

[4WD]

Thanks for the comment. Are those an LSD, or a full on-demand locker?

Mechanical locker that uses clutches - they don’t proportion …
Both tires have always pulled on mine …

 

[OLEJOE]

Gotcha. Do the later model Ram trucks still have the AAM axles in them?

Yes they do but the late models have gone to the clutched LSD. I think the other one is available as an option but Im not sure. I have both front and back are open diffs. I’ve only used the 4 wd one time and I was stuck on wet grass in my yard with the nose of the truck down hill.

 

[weasley]

You're comparing two different products - Mobil Delvac 1 Gear Oil 75W-90 and Mobil Delvac 1 Gear Oil LS 75W-90.

 

[DuckRyder]

Delvac 1 in the US does not have friction modifiers. We've covered it before in the Eaton Truetrac discussions.

 

[Snagglefoot]

You're comparing two different products - Mobil Delvac 1 Gear Oil 75W-90 and Mobil Delvac 1 Gear Oil LS 75W-90.

Here’s the info.