I have a 2004 Ram 3500 CTD with the 11.5" rears and limited slip. I use it to pull a horse trailer. I plan change the front and rear differential fluid. In the front 75w-90 Mobil 1. and in the rear 75w-140 AMSOIL SG. The book calls for 75-90 but that seems thin to me based on past experience. I called my local dealer and they said 75-90 is the book but they have used 75-140. I thought that 75-140 would act like 75-90 when cold but give me a little better top temp protection. With the down side being maybe slightly lower fuel economy. Any thoughts on this?
Downside to 75-140 vs 75-90 in my Ram 3500
- Thread starter TWHMAN
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One advantage of the thinner oils is that any air bubbles and foam created while the oil is churning can dissipate quicker. Air is not a very good lubricant, and as an insulator, could make a heavier oil actually run hotter if a lot of air is whipped in.
The Amsoil lookup guide recommends the 75W-140 SG for the LS rear end, with the addition of Slip-Lock if you experience chatter.
Using diff brands of gear oil for front and rear, what's the idea behind that?
Using diff brands of gear oil for front and rear, what's the idea behind that?
I think you made a good decision that was biased towards durability (vs fuel economy) with the 75W-140 since you are pulling a horse trailer and have a limited slip. Clutch-based limited slip diffs tend to run hotter than open diffs.
For sure don't use Amsoil SVG 75W-90 in the rear of that rig - and I believe you are saying you will use SVO 75W-140.
75W-90 maybe OK in the front, but still I would advise 75W-110 SVT in the front. There really are no downsides, and I doubt you will notice any MPG loss.
Amsoil SVT 75W-110 LINK
Use this to your advantage: http://www.lubrizol.com/J306.aspx?id=33216&terms=J306
75W-90 maybe OK in the front, but still I would advise 75W-110 SVT in the front. There really are no downsides, and I doubt you will notice any MPG loss.
Amsoil SVT 75W-110 LINK
Use this to your advantage: http://www.lubrizol.com/J306.aspx?id=33216&terms=J306
I would put in the Mobil 1 75-90 in both the front and back if that is the weight recommended to you from the manual. As far as being worried about towing... You bought a Ram 3500, I think Dodge expected its consumers to tow with it. Otherwise they wouldn't have went with the 3500.
If Dodge thought the best weight for their 3500 was 75-140, they would have recommended it.
If Dodge thought the best weight for their 3500 was 75-140, they would have recommended it.
I agree with 360kid on that Dodge expected you to tow. They spec 75w90 in the the 2500/3500 and 75w140 in the 1500s. I thought it was to do with the some of different rear plates or something. Regardless, I would use what they spec in the rearends. I dont think you are going to gain much, plus they call for 30,000 mile changes with synthetic yet, which anything will last the long. Another note is that large triaxle trucks also spec 75w90, for some reason 75w90 is preferred in all towing or heavy load situations by the manufacturer.
I neeed to correct that it is 15,000 miles per rearend change with a synthetic oil. Is that insane intervals or what?
Pablo why no SVG 75W-90 is AMSOIL not up to the task or what you state it as if it would blow up or some thing. With that said I would run 75W-110 but would have no fear of a quality 75W-90 if that is what OEM recommened. My choice is schaeffer SYN 293 75W90
Originally Posted By: dave123
Pablo why no SVG 75W-90 is AMSOIL not up to the task or what you state it as if it would blow up or some thing. With that said I would run 75W-110 but would have no fear of a quality 75W-90 if that is what OEM recommened.
Because Amsoil (via the manufacturer) recommends 75W-140 and Amsoil follows the new SAE J306. Of course Amsoil is up to the task.
Pablo why no SVG 75W-90 is AMSOIL not up to the task or what you state it as if it would blow up or some thing. With that said I would run 75W-110 but would have no fear of a quality 75W-90 if that is what OEM recommened.
Because Amsoil (via the manufacturer) recommends 75W-140 and Amsoil follows the new SAE J306. Of course Amsoil is up to the task.
Pablo I am confused on your reply to Dave123? You are saying that Dodge recommends 75w-140 for 2500/3500? I have a 2500 CTD and I followed 1. Mfg recommended weight and 2. Amsoil site using the lookup for my truck specifically.
I don't recall seeing 75w-110 as a recommended fill for the front or rear diff on the Amsoil site either?
I don't recall seeing 75w-110 as a recommended fill for the front or rear diff on the Amsoil site either?
2004 Ram 3500 CTD with the 11.5" rears and limited slip is not specifically listed. But this is for the 2004 Ram 3500 CTD:
Limited Slip Differential, Rear 9.25......GL-5*
All TEMPS......75W-140 [1] [3]
SEVERE GEAR 75W-140 Synthetic EP Lubricant (SVOQT)
80W-140 Synthetic Long Life Gear Lube (FGO05)
[1] Synthetic based oil.
[3] Trac-lok equipped axles require Limited Slip Additive be
added to the lubricant.
Limited Slip Differential, Rear 9.25......GL-5*
All TEMPS......75W-140 [1] [3]
SEVERE GEAR 75W-140 Synthetic EP Lubricant (SVOQT)
80W-140 Synthetic Long Life Gear Lube (FGO05)
[1] Synthetic based oil.
[3] Trac-lok equipped axles require Limited Slip Additive be
added to the lubricant.
The 11.5 inch AA on the 2004 CTD is listed as 75w-90 on the Amsoil site. I still don't see any mention of anything other than 75w-90 for the 11.5 rear diff on the 2500/3500 trucks which leads to me my next question (forgive me as I am not very knowledgable about Amsoil)--
Does the website receive frequent updates and/or are you just advocating that there is a better gear lube regardless of what the site says and if so, you are doing this based on your own opinion NOT an offical acknowledgement or endorsement from our friends at Dodge/Mopar?
Does the website receive frequent updates and/or are you just advocating that there is a better gear lube regardless of what the site says and if so, you are doing this based on your own opinion NOT an offical acknowledgement or endorsement from our friends at Dodge/Mopar?
You are correct about the recommendation for the 11.5" diff. But THWMAN has a limited slip diff. The site receives it's information from the manufacturer via a data service (alldata (?)) and is regularly updated.
I can ask Amsoil on Monday to clarify.
I can ask Amsoil on Monday to clarify.
We could all call 10 differnt lube MFG and get 10 differnt tech guys with 10 differnt reasons as to what weight lube to run with all differnt pros and cons to this that and the other thing. I guarantee we will learn nothing new with a phone call to AMSOIL.
Originally Posted By: dave123
We could all call 10 differnt lube MFG and get 10 differnt tech guys with 10 differnt reasons as to what weight lube to run with all differnt pros and cons to this that and the other thing. I guarantee we will learn nothing new with a phone call to AMSOIL.
In a way I agree with you. But since the Amsoil guide doesn't directly mention the 11.5" w/limited slip, it's worth asking the question, IMHO.
We could all call 10 differnt lube MFG and get 10 differnt tech guys with 10 differnt reasons as to what weight lube to run with all differnt pros and cons to this that and the other thing. I guarantee we will learn nothing new with a phone call to AMSOIL.
In a way I agree with you. But since the Amsoil guide doesn't directly mention the 11.5" w/limited slip, it's worth asking the question, IMHO.
75w90 is the recommended weight for the 11.50AAM...a lot of dealers "recommend" 75w140 in these trucks if you tow heavy/often (this is not to be confused with the 75w140 requirement for the 1500). Further, the LSDs in the AAMs do NOT require LSD additive by design.
A lot of owners do a lot of miles on nothing more than 75w90. Personally, I have over 212k on my 11.50AAM, the first oil change was 50k (Mobile 1 75w90), the second 80k (Royal Purple 85w140), and tomorrow at 212k (Schaeffers 75w140). But I also have an extra capacity aluminum cover that helps (I highly recommend this addition).
I personally don't believe the 15k interval (besides, if you read the schedule; that's a "severe" duty service; there is no recommended change interval for a "regular" service). Seems like the waste of a lot of $$ and oil for an application that hasn't "changed" in over 50 years.
YMMV
A lot of owners do a lot of miles on nothing more than 75w90. Personally, I have over 212k on my 11.50AAM, the first oil change was 50k (Mobile 1 75w90), the second 80k (Royal Purple 85w140), and tomorrow at 212k (Schaeffers 75w140). But I also have an extra capacity aluminum cover that helps (I highly recommend this addition).
I personally don't believe the 15k interval (besides, if you read the schedule; that's a "severe" duty service; there is no recommended change interval for a "regular" service). Seems like the waste of a lot of $$ and oil for an application that hasn't "changed" in over 50 years.
YMMV
I can only tell you that after 300+ miles of highway, 4.10s, and only a 1500 pound trailer, the rear only registered 136*F. Keep in mind that's with almost 9 quarts of oil and an aluminum cover. I haven't ever measured the rear after towing heavy because they are typically only short trips.
I don't think there is a recommended fluid for "best lockup". I know it took a load of about 10k to finally break my LSD loose and cause it to function correctly. I have only had it function correctly with RP 85w140, and when it applies, it applies fully. Keep in mind these apply harder the more load they are subjected to...until the tires slip.
Also, the 75w90 specification comes from AAM, not Dodge. From what I have read, they have indicated to guys that have contacted them, that 75w90 will function acceptably in 99% of the truck applications.
I don't think there is a recommended fluid for "best lockup". I know it took a load of about 10k to finally break my LSD loose and cause it to function correctly. I have only had it function correctly with RP 85w140, and when it applies, it applies fully. Keep in mind these apply harder the more load they are subjected to...until the tires slip.
Also, the 75w90 specification comes from AAM, not Dodge. From what I have read, they have indicated to guys that have contacted them, that 75w90 will function acceptably in 99% of the truck applications.
Originally Posted By: deeter16317
I can only tell you that after 300+ miles of highway, 4.10s, and only a 1500 pound trailer, the rear only registered 136*F. Keep in mind that's with almost 9 quarts of oil and an aluminum cover. I haven't ever measured the rear after towing heavy because they are typically only short trips.
I don't think there is a recommended fluid for "best lockup". I know it took a load of about 10k to finally break my LSD loose and cause it to function correctly. I have only had it function correctly with RP 85w140, and when it applies, it applies fully. Keep in mind these apply harder the more load they are subjected to...until the tires slip.
Also, the 75w90 specification comes from AAM, not Dodge. From what I have read, they have indicated to guys that have contacted them, that 75w90 will function acceptably in 99% of the truck applications.
I agree. If you are not seeing hi temps, there is no good reason to run a 140 grade. But you are only going to know that with a diff oil temp gauge. If you tow heavy and don't have one, the safest bet is to run the heavier oil, I suppose. Also, the 11.5 AAM is offered with the gear type limited slip, as well as the plate type. I know from my own testing that these type of diffs do not increase the diff oil temp substantially. . Even a plate type shouldn't much going straight down the road.
I'll climb on the soapbox here and recommend that anyone who tows regularly should have a diff temp gauge. AutoMeter and Isspro both make them and the Mag Hytec finned cover (another great addition) is plumbed for a gauge. Towing at or near the truck's maximum , especially uphill or against headwinds (or too fast ( : < ) can l generate high gear oil temps. That said, the 11.5 AAM is known for being a cool runner, relatively speaking.
I can only tell you that after 300+ miles of highway, 4.10s, and only a 1500 pound trailer, the rear only registered 136*F. Keep in mind that's with almost 9 quarts of oil and an aluminum cover. I haven't ever measured the rear after towing heavy because they are typically only short trips.
I don't think there is a recommended fluid for "best lockup". I know it took a load of about 10k to finally break my LSD loose and cause it to function correctly. I have only had it function correctly with RP 85w140, and when it applies, it applies fully. Keep in mind these apply harder the more load they are subjected to...until the tires slip.
Also, the 75w90 specification comes from AAM, not Dodge. From what I have read, they have indicated to guys that have contacted them, that 75w90 will function acceptably in 99% of the truck applications.
I agree. If you are not seeing hi temps, there is no good reason to run a 140 grade. But you are only going to know that with a diff oil temp gauge. If you tow heavy and don't have one, the safest bet is to run the heavier oil, I suppose. Also, the 11.5 AAM is offered with the gear type limited slip, as well as the plate type. I know from my own testing that these type of diffs do not increase the diff oil temp substantially. . Even a plate type shouldn't much going straight down the road.
I'll climb on the soapbox here and recommend that anyone who tows regularly should have a diff temp gauge. AutoMeter and Isspro both make them and the Mag Hytec finned cover (another great addition) is plumbed for a gauge. Towing at or near the truck's maximum , especially uphill or against headwinds (or too fast ( : < ) can l generate high gear oil temps. That said, the 11.5 AAM is known for being a cool runner, relatively speaking.
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