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75w-140 #4504951
09/01/17 09:33 PM
09/01/17 09:33 PM
Joined: May 2015
Posts: 186
East Coast
Fasttimez Offline OP
Fasttimez  Offline OP
Joined: May 2015
Posts: 186
East Coast
Question, Ford for years spec'd 75w-140 for their diffs. Even going so far as to back spec the rears that came with 80w-90 to 75w-140. Well in 2015, they switched to 75w-85. Is this purely for fuel economy reasons ? I bought AmsOil 75w-110 to put in my rear thinking it was the same 75w-140 because I dont tow heavy at all when I do. So why the extreme switch to the thinner lube ?

Last edited by Fasttimez; 09/01/17 09:35 PM.
Re: 75w-140 [Re: Fasttimez] #4504973
09/01/17 10:14 PM
09/01/17 10:14 PM
Joined: Jul 2015
Posts: 129
Alberta
BigJakeChevy Offline
BigJakeChevy  Offline
Joined: Jul 2015
Posts: 129
Alberta
I run the SG 75w110 in my chevy spec'd for 75w90. Over 200,000kms since I've owned the truck using that in the rear diff. Currently at 423,000kms still running strong, no howling or anyother noises.


2007 Silverado Classic 1500 Crewcab 5.3L 460,000kms
Engine oil Mobil 1 0w40fs
Oil Filter Fram Ultra 10575
Trans Oil Amsoil Torque Drive
Front Diff Amsoil SG75w90
T-Case Autotrak II
Rear Diff Amsoil SG75w140
Re: 75w-140 [Re: Fasttimez] #4504975
09/01/17 10:14 PM
09/01/17 10:14 PM
Joined: Apr 2010
Posts: 13,537
Chicago, IL
dparm Offline
dparm  Offline
Joined: Apr 2010
Posts: 13,537
Chicago, IL
It's possible that the newer basestocks are providing similar performance as the older stuff without the need for something overly thick. We see this with engine oils, so why wouldn't it apply to other lubricants such as gear oil?


2017 Chevrolet Corvette Grand Sport
Re: 75w-140 [Re: Fasttimez] #4504984
09/01/17 11:05 PM
09/01/17 11:05 PM
Joined: Sep 2010
Posts: 7,594
Planet Earth
2015_PSD Offline
2015_PSD  Offline
Joined: Sep 2010
Posts: 7,594
Planet Earth
Originally Posted By: Fasttimez
Well in 2015, they switched to 75w-85.
Which vehicle? My 2015 F-250 still specifies 75W-140. I would use 75W-110 instead of 75W-90 because Pablo said some years ago that when the J306 tables were updated that 75W-110 had the upper viscosity range that 75W-90 had before the update.

Re: 75w-140 [Re: Fasttimez] #4505005
09/02/17 12:21 AM
09/02/17 12:21 AM
Joined: Oct 2004
Posts: 3,183
Midwest, Illinois
beanoil Offline
beanoil  Offline
Joined: Oct 2004
Posts: 3,183
Midwest, Illinois
My 2003 SuperDuty manual indicated 75w140, my 2016 has the same specification, so I don't see any changes. YMMV.
I ran 85w140 Delo in my 2003, with RL LS additive, because I had it and could. Much thicker than synthetic 75w140, but the truck did not mind in the least.
I'm about due for a diff change on the 16. I'm considering Amalie 75-85w140 synthetic. I can get that from their webstore.
I cannot find Delo 75w140 anywhere, and Redline is just so expensive. I'm a 30k and done guy on diff lubes, so price vs. performance comes strong into play here.


beanoil: Tough under heat, real dirty afterwards.
Re: 75w-140 [Re: Fasttimez] #4505074
09/02/17 05:12 AM
09/02/17 05:12 AM
Joined: Aug 2013
Posts: 406
Alberta
tcp71 Offline
tcp71  Offline
Joined: Aug 2013
Posts: 406
Alberta
My 2009 F150 called for 75w140. My new 2016 F150 has the 75w85 spec. Same 9.75" axel in both trucks. Higher tow rating in the 2016 and both trucks are supercrew6.5ft box trucks. I still have 5 litres of Ford 75w140 in my stash. I will change the fluid once the new axel breaks in fully back to 75w140. Only 5000 miles on the 2016 so far. Suspect it is a fuel economy thing.


2016 F150 Eco: Edge 0w40
2005 Sienna 3.3: mobil 0w40 (varies)
Re: 75w-140 [Re: Fasttimez] #4505104
09/02/17 06:04 AM
09/02/17 06:04 AM
Joined: Nov 2003
Posts: 954
Houston, TX
Tones Offline
Tones  Offline
Joined: Nov 2003
Posts: 954
Houston, TX
Fuel economy. Same reason they switched to aluminum, switched to turbos and smaller engines.

Last edited by Tones; 09/02/17 06:04 AM.

'15 Toyota Avalon
'11 Toyota Corolla
'10 Honda Civic
'16 Ford F-150 Supercab 2.7TT
Re: 75w-140 [Re: tcp71] #4505116
09/02/17 06:19 AM
09/02/17 06:19 AM
Joined: Sep 2010
Posts: 7,594
Planet Earth
2015_PSD Offline
2015_PSD  Offline
Joined: Sep 2010
Posts: 7,594
Planet Earth
Originally Posted By: tcp71
My 2009 F150 called for 75w140. My new 2016 F150 has the 75w85 spec. Same 9.75" axel in both trucks. Higher tow rating in the 2016 and both trucks are supercrew6.5ft box trucks. I still have 5 litres of Ford 75w140 in my stash. I will change the fluid once the new axel breaks in fully back to 75w140. Only 5000 miles on the 2016 so far. Suspect it is a fuel economy thing.
The only way to know for certain would be to check the axle temps to see if the oil is performing within its expected range. Far be it from me to disagree with a Ford engineer, but my 2010 FX4 also specified 75W-140 and if it were mine (especially with a higher tow rating and if you will be towing in that range), I would be installing Amsoil severe gear 75W-140.

Jim Allen stated more than once on this site the vast majority of axle wear occurs at less than 10K miles. You should change it soon. You can search for my UOAs on my 2010 and see the differences in wear metal production at the different stages.

Re: 75w-140 [Re: Fasttimez] #4505208
09/02/17 07:55 AM
09/02/17 07:55 AM
Joined: May 2015
Posts: 186
East Coast
Fasttimez Offline OP
Fasttimez  Offline OP
Joined: May 2015
Posts: 186
East Coast
Sorry guys, these changes were for the F150, not the F250 or F350. I'm going to change out to the SG 75w-110. After researching it seems the switch was made in an effort for better MPG.

Re: 75w-140 [Re: Fasttimez] #4505307
09/02/17 09:47 AM
09/02/17 09:47 AM
Joined: Oct 2004
Posts: 3,183
Midwest, Illinois
beanoil Offline
beanoil  Offline
Joined: Oct 2004
Posts: 3,183
Midwest, Illinois
I agree 2015PSD. I'll look into the AmSoil. It's available at Farm and Home. Frankly I always shy away from AmSoil because of the wild claims and marketing. But, I do listen when advice is given, especially if you give it.


beanoil: Tough under heat, real dirty afterwards.
Re: 75w-140 [Re: Tones] #4505758
09/02/17 06:49 PM
09/02/17 06:49 PM
Joined: Apr 2012
Posts: 2,698
West Michigan
buck91 Offline
buck91  Offline
Joined: Apr 2012
Posts: 2,698
West Michigan
Originally Posted By: Tones
Fuel economy. Same reason they switched to aluminum, switched to turbos and smaller engines.


Fuel economy and the lighter oil will keep it running fine until warranty is up. I can't imagine it'll do any favors for the 200k crowd... but who knows, might not be a problem?


2011 F150 4x4 5.0L
1996 Mustang GT 5spd/ragtop
Re: 75w-140 [Re: Fasttimez] #4506588
09/03/17 06:26 PM
09/03/17 06:26 PM
Joined: Nov 2003
Posts: 954
Houston, TX
Tones Offline
Tones  Offline
Joined: Nov 2003
Posts: 954
Houston, TX
Honestly, I always thought the 75W-140 was over the top for an F-150. Perhaps to combat neglect. Other manufacturers have used xw-90 weights for years.

Last edited by Tones; 09/03/17 06:32 PM.

'15 Toyota Avalon
'11 Toyota Corolla
'10 Honda Civic
'16 Ford F-150 Supercab 2.7TT
Re: 75w-140 [Re: Fasttimez] #4506596
09/03/17 06:32 PM
09/03/17 06:32 PM
Joined: Oct 2014
Posts: 12,581
Idaho
CT8 Offline
CT8  Offline
Joined: Oct 2014
Posts: 12,581
Idaho
I use 75W-140 syn in all the differentials .


2015 Ford F150 2.7
2018 Ford F350 6.2
Re: 75w-140 [Re: Fasttimez] #4506890
09/04/17 12:13 AM
09/04/17 12:13 AM
Joined: Mar 2013
Posts: 496
Australia
Ducman Offline
Ducman  Offline
Joined: Mar 2013
Posts: 496
Australia
It's an interesting question.

I assume it's simply for fuel economy.
Which is all fine and good for now I suppose.

My latest vehicle has a ZF rear end where the manufacturer exclusively specifies a 75w-85 GL5 oil which meets the ZF TE ML-18 spec.
I believe the factory fill is Castrol SAF Carbon mod which is supposed to be the bees knees for these diffs.
Like the transmission gear oil(ATF) the diff is deemed to be a lifetime fill according to all references, but I will change the oil in the Diff and Transmission at the first service interval(9 Months or 15,000 kms) along with the engine oil when I get to it at the 9 month mark which will be >12,000 kms.

The service booklet states an inspection of fluid level at 45,000 km service intervals.
I don't exactly know how that would be handled at the dealership level, but I assume it will simply be a matter of a visual check for leaks or weeps.

I will be sticking with the specified fluid whilst the vehicle is in Warranty or until I know more about what's so special about Castrol SAF Carbon mod. Apparently it's designed for these Diffs with Carbon limited slip linings.
But my intention is to change the fluid at around the 45,000 km mark rather than merely inspect for leaks whilst under warranty.
I will perform a UOA at each change and monitor the wear metals accordingly to try to determine if a thicker Diff oil will be advantageous and make my decision after a clear wear metal trend is established.
It's the only way to know for sure if this light Diff oil is actually fit for purpose.
So for now I am keeping an open mind on the matter.
Perhaps my Diff is designed around this type of fluid so all will be good.

You seemingly have some viable options.

Last edited by Ducman; 09/04/17 12:14 AM.
Re: 75w-140 [Re: Tones] #4506900
09/04/17 12:32 AM
09/04/17 12:32 AM
Joined: Mar 2013
Posts: 496
Australia
Ducman Offline
Ducman  Offline
Joined: Mar 2013
Posts: 496
Australia
Originally Posted By: Tones
Honestly, I always thought the 75W-140 was over the top for an F-150. Perhaps to combat neglect. Other manufacturers have used xw-90 weights for years.


Quite right.

Interestingly I have a vehicle that requires a full synthetic 80w-140 GL5 oil along with the recommended Sturaco additive or a rear end failure is likely over time.
The design was prone to problems from the start and I believe the manufacturer had specified the now obsolete Mobil SHC ID 80w-140 after extensive lube testing to try and curb the failure rate.

In the very distant past I have also seen the then specified EP 90 GL5 gear oil run out like putrid water after the Pinion had nearly welded itself to the Crown wheel in a way over-driven Ford 9".
These days nobody here in OZ will run anything much less than a straight SAE 140 GL5 mineral oil(near impossible/impossible to get) in the Ford 9".

Other Diff designs seemingly go for a good many years on the factory fill 75w-85 GL5 oils with the vehicle falling apart around it.

I have learnt.
It all depends upon the application.

Last edited by Ducman; 09/04/17 12:35 AM.
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