question hoping for quick answer
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Postmaster
Joined: Aug 2001
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From: Trussville, Alabama
question hoping for quick answer
2005 F150
Not LS rear end
I have to replace a leaking axle seal, so I get to open the diff and must therefore replace the fluid.
Ford calls for 75W-140 fully synthetic.
Local shop has one bottle, but several of same gear oil in Valvoline conventional (not synthetic)
QUESTION: Is synthetic necessary for my application or does Ford spec it because it could be considered "lifetime" and no drain/replace interval needed?
Thanks in advance for any help.
edit to add: I just looked back (online) at some mid-late 90's model F150 specs.
Those call for 80W90 conventional. I don't think the rear end has changed, so that really makes me wonder if the 75W-140 is required.
What should I do?
Go with the synthetic?
Use 75W-140 conventional?
Use 80W90 conventional?
Thanks!
Not LS rear end
I have to replace a leaking axle seal, so I get to open the diff and must therefore replace the fluid.
Ford calls for 75W-140 fully synthetic.
Local shop has one bottle, but several of same gear oil in Valvoline conventional (not synthetic)
QUESTION: Is synthetic necessary for my application or does Ford spec it because it could be considered "lifetime" and no drain/replace interval needed?
Thanks in advance for any help.
edit to add: I just looked back (online) at some mid-late 90's model F150 specs.
Those call for 80W90 conventional. I don't think the rear end has changed, so that really makes me wonder if the 75W-140 is required.
What should I do?
Go with the synthetic?
Use 75W-140 conventional?
Use 80W90 conventional?
Thanks!
Last edited by BrianA; Oct 24, 2007 at 12:23 PM.
Post Fiend
Joined: Jan 2003
Posts: 9,748
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From: Connecticut
Originally Posted by BrianA
QUESTION: Is synthetic necessary for my application or does Ford spec it because it could be considered "lifetime" and no drain/replace interval needed?
I think you will be more than OK with conventional Valvoline.
Lead Driver
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From: Scio, OR
My Dad had a 99 Ford Ranger that called for the 75W-150 Synthetic, with a friction modifier for the traction lock differential. He took it to a Chevron lube place and had the differential oil changed and they put in regular non-synthetic oil. About 10,000 miles later we were changing wheel bearings and differential bearings.
It's not that expensive.
It's not that expensive.
Post Fiend
Joined: Jan 2003
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From: Connecticut
Originally Posted by dchamberlain
My Dad had a 99 Ford Ranger that called for the 75W-150 Synthetic, with a friction modifier for the traction lock differential. He took it to a Chevron lube place and had the differential oil changed and they put in regular non-synthetic oil. About 10,000 miles later we were changing wheel bearings and differential bearings.
I can assure you that the failure of all those bearings (most particularly the wheel bearings) on your Dad's Ranger did not occur because of the fact that conventional gear oil was used in the rear differential.
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
The '99 Ranger Owners Manual does not specify synthetic fluid for the rear differential. Instead, it calls for "Motorcraft SAE 80W90 Premium Rear Axle Lubricant" (Ford Part # XY-80W90-QL, Ford Specification # WSP-M2C197-A).
And, I'll be the first to admit that it may have entirely been a coincidence. But, does the OP really want to take that chance? My understanding from the Ford guy was that the clutch plates in the differential caused a bit of friction and heat and were tougher on the oil than on a standard differential.
Here is another point to ponder. If it's just about one time fill and fuel mileage, why does the rear (limited slip) differential on my 2004 F-250 call for 75W-150, but the front (not limited slip) differential only call for 80W-90 non synthetic.
My only point being that why take a chance? The right oil costs a lot less than the repair.
Last edited by dchamberlain; Oct 24, 2007 at 07:57 PM.
Cargo Master
Joined: Apr 2003
Posts: 2,057
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From: Too close to Houston
Originally Posted by BrianA
2005 F150
Not LS rear end
I have to replace a leaking axle seal, so I get to open the diff and must therefore replace the fluid.
Not LS rear end
I have to replace a leaking axle seal, so I get to open the diff and must therefore replace the fluid.
Which axle is on the 150? If it's like the old 9" you don't have to drain the pumpkin to pull an axle and change wheel bearings and seals. If it's a C-clip axle I'd put the synthetic in. Doesn't have to be Motorcraft. My F-250 axle has had Lubrimatic synthetic with Lubrimatic friction modifier for the last 30,000 miles and is still working very well. Bought the stuff at O'Rielley's
Last edited by Sport45; Oct 24, 2007 at 10:44 PM.
Thread Starter
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Postmaster
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From: Trussville, Alabama
112,000 miles on it, so warranty is not an issue.
You do have to open the diff, remove bolt, slide out the pin, remove the c-clip and then slide out the axle shaft.
You do have to open the diff, remove bolt, slide out the pin, remove the c-clip and then slide out the axle shaft.
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Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
Originally Posted by dchamberlain
... My understanding from the Ford guy was that the clutch plates in the differential caused a bit of friction and heat and were tougher on the oil than on a standard differential.
Here is another point to ponder. If it's just about one time fill and fuel mileage, why does the rear (limited slip) differential on my 2004 F-250 call for 75W-150, but the front (not limited slip) differential only call for 80W-90 non synthetic.
Here is another point to ponder. If it's just about one time fill and fuel mileage, why does the rear (limited slip) differential on my 2004 F-250 call for 75W-150, but the front (not limited slip) differential only call for 80W-90 non synthetic.
Anyway, the axle in question for this thread is open type.
The front drive axle does not work hardly at all. How many of us use 4x4 for more than a few hundred miles a year, if that. Also EPA mileage tests are conducted in 4x2. They put syn in the rear one primarily for mileage, with the bonus of "lifetime fill". 75W will give a tiny percentage gain compared to 80W, especially in the EPA test cycle, which doesnt load the axle very much so it is running cool.
Jim
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Elder User
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From: northern Michigan
Ford specs the full synthetic but also recommends a change out every 50,000 nmiles on the rear end. Also don't forget that a lot of these trucks had the limited slip diff and require a special additive for that be put in also.
Closely inspect the rear diff. cover also. Ford has a problem with the OEM ones rusting through after only a few years in the rust belt states.
Closely inspect the rear diff. cover also. Ford has a problem with the OEM ones rusting through after only a few years in the rust belt states.
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Postmaster
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From: Trussville, Alabama
As it turns out, I have yet to need the oil.
But hopefully tonight
https://www.ford-trucks.com/forums/6...rear-diff.html
But hopefully tonight
https://www.ford-trucks.com/forums/6...rear-diff.html
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Postmaster
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From: Trussville, Alabama
I ran across an inexpensive fully syn option at a local independent auto parts store.
About $8/qt (75W140) and that was the best I could find syn for.
It is GL-5 compliant, so I reckon it's good enough for me!
It's all back together now and a short drive seems to indicate all truned out OK.
A very interesting experience
About $8/qt (75W140) and that was the best I could find syn for.
It is GL-5 compliant, so I reckon it's good enough for me!
It's all back together now and a short drive seems to indicate all truned out OK.
A very interesting experience
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