I was going to change the differential lubricant to Mobil 1 Synthetic which is 75W-90 The tag on the housing said to use 75W-140. Anyone know if it would cause any problems using the Mobil 1? All opinions welcome

Thanks!

 

Same here,
Lightning Supplement (little book that came with truck says 75/90
Maintenence Manual says 75/140

Redline comes in either, I am going to have dealer check with Ford First.

August MM&FF shows Jim at JDM using 75/140 Ford Synthetic.
Jim

 

I personally use a organtic[sp] lube that has an extremepressure additive in it.i have seen what the syn. stuff does to gears under extended pressure.Not very pretty, brgs look great thou. Stan

 

I just got the following responses from Royal Purple, Mobil and Red Line :

Royal Purple MaxGear 75W140.

At this time, it is packaged in 5 gallon pails.

Most applications specifying the 75W140 will perform excellently using our MaxGear 85W140 product.
This is available in both quarts and 5 gallon pails.

Both are rated for limited slip and API GL-5 applications with the 75W140 improving low temperature pumpability by a small margin
over the 85W140 product.

David Canitz
Royal Purple Ltd
Technical Services
------------------------------------------------------------------------------------

Mobil --

Thank you for your inquiry.

We regret to inform you at present time Mobil does not have a
recommendation for your 2001 Ford truck. We appreciate your interest nonetheless.
Thanks again.

The above information is provided in good faith based upon the
information presented by the customer. ExxonMobil is not responsible for

any loss or damage resulting from inaccuracies or errors in any of the
information provided or any acts or omissions taken in response to our
advise.
------------------------------------------------------------------------------------

Redline--

The Red Line 75W140NS plus 5% Friction Modifier is the fluid we would
recommend for your Lightning pick up differential.

Thank you for your interest in Red Line Oil.

 

So, what is the verdict? I just replaced my diff fluid with 2 bottle of friction modifier about 5 quarts of 75-140 synthetic like the differential tag says. I just read in the owners manual, thanks to Bfb, that we are supposed to use 80-90 premium. I did search and really found nothing concrete. I called SVT and they said 80-90 like the owners manual says. When I asked them why the differential says 75-140 they said use what the manual says. Who is right? Differential cover or SVT manual? I could have saved a lot of money if I used 75-90, about $70.

 

The SVT supplement included with the manual states 80w-90 and this is what we should use. He also put me on hold for a few minutes to investigate further and came back with the same response.

It seems to me that although we could use the 75w-140 it makes no sense in our situation since we're mainly worried w/ performance instead of a work truck. I'd imagine if you used your Lightning for purposes that a Diesel or a normal F150 was used for then possibly go w/ the 75w-140.

I'm thinking that there is nothing different in the housing than over other 9.75" rear ends used in other Ford trucks (should be off the shelf parts). SVT told me, "You're probably right." This doesn't mean my thinking is, but it is logical to feel this way.

Also, look for my post concerning the " '01 Owners will receive updated Owner's Guide Supplement".

BfB

 

Are these rear ends built specifically for the Lightning? If so why do they have the 75-140 synthetic only tag on the differential cover? If they are also used in other trucks do they come prefilled from the rear end maker? Or do they ship dry and at the SVT plant they put 80-90 oil in them?
I changed out my oil and it seemed thicker than a 80-90w oil.

 

I'm almost positive that they are off the shelf rear ends, meaning just drop-ins. This is the same rear that is used in the Diesel.

Good "?", but there isn't any type of "SVT" Lightning specific plant, honestly. You most likely mean the plant that the Lightning is built in. I'm pretty sure they are built alongside other F150's. Normally the rear-ends are tested after they are produced and before they are installed, so I'd imagine that they come prefilled before they stick them in the rear of the vehicle.

It was probably a 75w-140. Old lube normally is broken down and thicker, but all Ford rear ends have synthetic from the factory so they probably will hold up for years in viscosity and thickness, so what you were seeing was most likely a thicker lube.

From my experience on rear ends I would believe that an 80w-90 will not hurt this rear end at all. I believe it would be a better performance modification to help produce LESS friction.

After learning about these trucks it becomes common sense that there is no way that the drivetrain on this truck and other F150s could be very efficient (no matter what some will want you to believe). When you start investigating it then you realize that they aren't all that efficient too!

I'd appreciate it if others that have knowledge on this to PLEASE respond to this thread so we can help put some closure to what we need to be using for sure.

BfB

 

It almost sounds impossible that they come with 80-90w, but I guess anything is possible. That 80-90w premium is sure a lot cheaper than 75-140 synthetic! I wonder how much time this is worth in the 1/4th mile, if I change it out?

 

Probably .001

It's not going to be much probably. You may free up 1 rwhp, who knows.

Give me a chance to get some more info. before you do this.

BfB

 

Well I went out and got some 75-90 mobil 1 synthetic, and additive. I'll change out that 75-140 I put in a couple of weeks ago. Unless someone tells me different in the next few minutes.

 

I just got back from a test run. I didn't hear anthing different so I guess the 75-90 will work okay. I added a tube of friction modifier stuff also.

 

Which brand? Mobil 1?

Lemme know!

Take care,

BfB

 

4.5 quarts Mobil 1 75-90 synthetic and a 7oz tube of Trans X.
That 75-140 I put in the other day was really dirty. Not as dirty as what came from the factory...whatever that was. It didn't take but 5 mins. to drain and refill. I love that new cover.

'01 black lightning 14,300 miles. Oil change later today and next week the fuel filter.