Amsoil 75w-110 -- 2002 Ford F-150

[TexasTDI]

I just bought a 2002 Ford F-150 with 93k miles. I'm planning on changing the rear dif fluid at 100k miles. Ford recommends 75w-140.

This truck will just be used as a commuter vehicle to and from work and college. I might drive 250 miles a week at best. Lots of stop-and-go traffic. No loads or trailers.

Can I use Amsoil 75w-110 instead of 75w-140?

Will I need to use Amsoil's Slip-Lock additive?

Thanks!

 

[TimVipond]

I advise against it. Use the AMSOIL SVO 75W140 and no AMSOIL Slip-lock additive.

The 75W110 can be used in place of a 75W90 but not a 75W140. Under the new SAE gear lube viscosity definition, the 75W110 is on the heavy half of the old 75W90 spec.

The AMSOIL 75W90 already has the slip lock additive blended into it. AMSOIL made it to be added to non AMSOIL gear lubes that do not have this additive.

 

[Pablo]

In Texas? Use what Ford recommends.

In Alaska - I might change my tune.

The limited slip additive is generally not needed. Is the diff. an anti spin unit?

 

[TeeDub]

I think the 75w-110 would work just fine under these conditions and the axle would run that much cooler. I would suggest testing the first batch of gear lube after 30,000 miles and looking at the wear rates, however.

Change out the factory fill after 10,000 miles, as most of the break in wear occurs over this period.

Ted

 

[Stooge]

I would highly recommend that if your differential is a Trac-Loc, to use one or two 4 oz. bottles of FORD Slip Loc Additive in addition to the Severe Gear Gear Oil of the viscosity you finally choose. Every Ford Trac-Loc I've used with Amsoil's gear oils with the additive already there has moaned around turns. I've used Amsoil Slip-Loc additive with no success. Only the Ford stuff seems to work in these differentials.

 

[msparks]

I changed out to 75w90 in My 97 F150 that spec'd the 75w140. I like you never hauled large loads and used it mostly for communting.

Even after long trips with moderate loads, the rear end was only warm to the touch. You could also possible see a few mpg improvement with the thinner stuff.

I say go for it.

 

[TeeDub]

Michael,

My point, exactly....the diff will run that much cooler with the thinner lube, which is VERY beneficial when it comes to maximizing the life of elastomeric seals in the axles.

 

[Mike_dup1]

fwiw

Here is the info from the current Action News

Quote:

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SEVERE GEAR 75W-90 (SVG) replaces competitive 75W-90 and 80W-90 gear lubricants. It delivers the best fuel efficiency and cold temperature performance in the SEVERE GEAR line.

SEVERE GEAR 75W-110 (SVT) replaces competitive 75W-110, 75W-90 and 80W-90 gear lubricants. It delivers better viscosity protection than SEVERE GEAR 75W-90 and better fuel efficiency than SEVERE GEAR 75W-140.

SEVERE GEAR 75W-140 (SVO) replaces competitive 75W-140, 80W-140 and 85W-140 gear lubricants. It is recommended wherever these viscosities are required by equipment
Manufacturers.

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[TexasTDI]

Quote:

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I would highly recommend that if your differential is a Trac-Loc, to use one or two 4 oz. bottles of FORD Slip Loc Additive in addition to the Severe Gear Gear Oil of the viscosity you finally choose. Every Ford Trac-Loc I've used with Amsoil's gear oils with the additive already there has moaned around turns. I've used Amsoil Slip-Loc additive with no success. Only the Ford stuff seems to work in these differentials.

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How can I tell if my rear dif is a Trac-Loc?

 

[sfam198]

Quote:

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How can I tell if my rear dif is a Trac-Loc?

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Easiest way to tell is to look on the door jamb sticker, under AX, read the number (or a letter and a number) Then go to this page and look it up. For example, on my truck, the axle code is 19, which when you look it up, tells you that I have a 3.55 open diff.

 

[TexasTDI]

Quote:

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Easiest way to tell is to look on the door jamb sticker, under AX, read the number (or a letter and a number) Then go to this page and look it up. For example, on my truck, the axle code is 19, which when you look it up, tells you that I have a 3.55 open diff.

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Thanks for the info!

My axle code is 19 as well.

 

[wileyE]

My Ford book gives you the option of using the 90w or 140w for heavy duty use. Done it both ways in 3 different trucks and can say there was no change in mpg. Figure might as well use the 140. Same story as others on the limited slip additives, they might have enough for top off, but doing a complete change you usually need to add some more.

 

[Junior]

Quote:

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Michael,

My point, exactly....the diff will run that much cooler with the thinner lube, which is VERY beneficial when it comes to maximizing the life of elastomeric seals in the axles.

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Do you have any data that shows a lighter lube results in cooler operating temperatures in a hypoid gearset???? I don't think that statement is correct. Fluid level will have a much greater affect on fuild temp. Too full tends to create excess heat. An unless your rear axle consistently operates above 200F the seals will be fine.

 

[ewetho]

Use the 140. Ford replaced 80W-90 with the 140 even in existing cars because of rear end problems. The 140 prevent the problems to a MUCH MUCH greater extent. Very few problems versus quite a few more. Just get out the Synthetic 140 and go.

 

[TeeDub]

Junior,

It's simply a matter of fluid mechanics....

Consider the amount of energy needed to stir a glass of honey, as opposed to a glass of water. Since the net energy of a closed system can not be lost or gained, simply converted, that energy goes directly into heating the fluid. . This is one of the primary laws of thermodynamics and is true regardless of the type of fluid we are talking about. The same thing is true of engine oils,ie an thicker oil will run hotter.

If you want to prove this to yourself, install an accurate oil temp gauge on your engine and try running various viscosity oils. You'll see what I mean right away...

My Audi came from the factory with a very accurate, "VDO" oil temp gauge. The difference between running a 30wt oil and a 50wt oil under the same conditions is about 10F-15F, simply due to the greater "intrafluid" friction of the more viscous fluid. The same principal holds for a 75w-90 gear lube with a viscosity of approx 15-16 Centistokes (Cst), compared to a 75w-140 gear lube with a viscosity of 24-26 Cst (much thicker at operating temp).

The other factor here is that thinner lubricants have better (higher) heat transfer coefficients. So they do a better job of transferring heat to the axle or transmission housing.

TD

 

[TexasTDI]

Here are the specs for both fluids, 75w-110 and 75w-140. I honestly don't know what they mean, that's why I'm here to learn.

Kinematic Viscosity @ 100°C, cSt -- 20.4 / 25.7

Kinematic Viscosity @ 40°C, cst -- 143.7 / 185.6

Viscosity Index -- 164 / 173

Brookfield Viscosity @-40°C, cP -- 118,728 / 124,210

Based just on the fluids specs, would it be OK for me to use a 75w-110 fluid instead of the "recommended" 75w-140 fluid?

 

[Junior]

Quote:

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Junior,

It's simply a matter of fluid mechanics....

Consider the amount of energy needed to stir a glass of honey, as opposed to a glass of water. Since the net energy of a closed system can not be lost or gained, simply converted, that energy goes directly into heating the fluid. . This is one of the primary laws of thermodynamics and is true regardless of the type of fluid we are talking about. The same thing is true of engine oils,ie an thicker oil will run hotter.

If you want to prove this to yourself, install an accurate oil temp gauge on your engine and try running various viscosity oils. You'll see what I mean right away...

My Audi came from the factory with a very accurate, "VDO" oil temp gauge. The difference between running a 30wt oil and a 50wt oil under the same conditions is about 10F-15F, simply due to the greater "intrafluid" friction of the more viscous fluid. The same principal holds for a 75w-90 gear lube with a viscosity of approx 15-16 Centistokes (Cst), compared to a 75w-140 gear lube with a viscosity of 24-26 Cst (much thicker at operating temp).

The other factor here is that thinner lubricants have better (higher) heat transfer coefficients. So they do a better job of transferring heat to the axle or transmission housing.

TD

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I don't disagree with what you are saying, I too have tanken physics, thermodynamice, fluid dynamics etc. But you must be careful when comparing an internal combusion engine to a gearbox. While in theory the lighter gear lube should run cooler, in practice that is not always the situation. You mention stirring a fluid. That I agree with. However, in a gearbox there is more going on than simple stirring. There are also a lot of high pressure areas between the gear teeth.

I work for an off road equipment manufacturer and we have data that shows a heavier lube, i.e. 75w140, is actually good for approximately 20F reduction in gearbox temperature in specific applications. If the lube isn't doing it's job it is going to get too hot.

Now in a hypoid gearset on a unloaded f-150 the lighter fluid may run cooler but start towing a load who knows what might happen.

I don't agree with your blanket statement that a lighter fluid will run cooler in every application. If that were true, there would be hydraulic fluid in every gearbox. We all know that isn't true

 

[Junior]

Quote:

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Here are the specs for both fluids, 75w-110 and 75w-140. I honestly don't know what they mean, that's why I'm here to learn.

Kinematic Viscosity @ 100°C, cSt -- 20.4 / 25.7

Kinematic Viscosity @ 40°C, cst -- 143.7 / 185.6

Viscosity Index -- 164 / 173

Brookfield Viscosity @-40°C, cP -- 118,728 / 124,210

Based just on the fluids specs, would it be OK for me to use a 75w-110 fluid instead of the "recommended" 75w-140 fluid?

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It probably won't hurt anything if you are not going to tow. (I wouldn't do it) I also don't think you will see a measureable MPG difference. Just my

 

[TexasTDI]

I went ahead with the recommended 75w-140.

 

[98LSC32V]

I just put the Amsoil 75w-110 in my 98 LSC 8.8 rear end, took 1.8 quarts.