75w-140

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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 ?
 
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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.
 
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?
 
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.
 
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.
 
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.
 
Fuel economy. Same reason they switched to aluminum, switched to turbos and smaller engines.
 
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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.
 
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.
 
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.
 
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?
 
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.
 
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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.
 
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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.
 
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Originally Posted By: Fasttimez
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 ?

Absolutely for fuel econcomy, or CAFE requiremwents though I'm not sure it may be adequate for one's softie application......and I've no no documents to support my position.
There is no such thing as a gear oil in xW140 being too thick in a differential.
 
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I don't have a truck so this is anecdotal from when I did and was considering taller gears. The stuff I read about diff lubes was basically that thicker is better for HD applications, and that thicker might make noise or feel a bit stiff on start in a really cold climate until the diff warms up a bit.

CAFE was well intentioned, but too aggressive in its time table as it seems to be creating all sorts of compromises that are impacting durability
 
Originally Posted By: beanoil
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.
I'll agree with the wild marketing ETC, but Amsoil makes a top quality product.
 
Our 4X4 2017 Explorer with the 2.3 Eco Boost rear diff spec's Ford's 80W-90 "Premium Fluid", which is not synthetic and is considered a "lifetime fill"
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. It's not even synthetic like the previous 75W-140 that Ford used in their previous rear diff Ford vehicles I've owned. I'll change it with a synthetic 75W-90 soon as we keep our vehicles a long time and I want to minimize future problems while they are cheap to do so by a simple fluid change.

Whimsey
 
Recommend you stay with the 75W110 SG since it is a good replacement for mineral 75W140 because it has good film strength and a heavy duty EP additive package.
 
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