Changing diff/transfer case oil to synthetic

I've just got a new truck, 2015 F-150. Just hit 2500 miles and I'm going to do an oil change. While I'm at it, I'm wondering if it be worth to also change the transmission differential and transfer case with synthetic oil?
Experienced mechanics share their insights in answering this question :
If you want to, you can, it is a very good oil. It doesn’t really need to be done at 2500 miles. That’s way [too early to change the oil]((https://www.yourmechanic.com/article/when-should-i-change-my-oil), in my opinion. But it is very good oil, and if you want to switch it out, you can go ahead and do it. Personally, I would wait to have any of these services done. You’re spending money on something that doesn’t need to be changed yet, but if you are going to do it in the future, you might as well start now.

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Most transfer cases are filled with an automatic transmission fluid, which is usually red in colour.
Ford introduced Mercon ATF in 1987 and Mercon is the recommended fluid for most 1997 to 2007 4×4 Ford transfer cases.
Genuine Ford Fluid XL-12 Transfer Case Fluid – 1 Quart , black.
Transfer cases may be filled with gear oil, automatic transmission fluid (ATF), or specialty lubricants. It is important to regularly inspect the transfer case for any damage, leaks, or other concerns.
The simple answer to what makes transmission fluid and gear oil different lies in the purpose that the two solutions were designed for. For instance, transmission fluid is formulated to work with automatic transmissions, while gear oil is typically engineered to work specifically with manual-type gear boxes.
Changing the transfer case fluid is important for several reasons: Lubrication: Transfer case fluid serves as a lubricant for the gears and bearings inside the transfer case. Replacing the fluid regularly helps to ensure that these components are properly lubricated and protected from wear and damage.
Transfer Case and Differential Fluid Change

SAE 75W-90 Motorcraft High Performance Synthetic Rear Axle Lube or equivalent.

The transfer case acts like a differential, but channels power to the two differentials on different axles rather than to two wheels on the same axle. As in a gearbox, a differential and transfer case require fluid to lubricate the gears, shafts and bearings where metal slides over metal.
You need Mercon LV as it replaced Ford`s Transfer Case Fluid a short while back.
The transfer case will take just under 1 liter of fluid so only one bottle is required.
Dexron IIE: First General Motors requirements fluid for electronic transmissions. Mercon Type CJ: This is a specialty transmission fluid for Ford C-6 transmissions. It is designed similar to General Motors Dexron II specification. This type of drive train fluid should not be used in automatics that require Type F.
Ford recommends using Motorcraft®* motor oil for your Ford vehicle. Using the right oil helps keep your vehicle`s engine clean, reduces overall wear, and maximizes performance.
Differential oil is sometimes referred to as gear oil and is found in the axle housing. It`s designed to perform under high-pressure situations, rather than high temperatures like engine oil. Differential fluid: Lubricates clutch packs, gears and bearings.
You should have your differential and transfer case fluid checked every 30,000 miles, or when you experience any of the symptoms below. Changing these fluids is a messy job, but your local Brakes Plus team is here to help – we never mind getting our hands dirty!
Manufacturers tend to recommend different maintenance intervals based on the type of vehicle and intended use, but generally speaking, it`s safe to perform a transfer case fluid service every 30,000 miles.
The transfer case is always working, whether you use the four wheel drive on your vehicle or not. Your transfer case fluid level should be checked every time that you get an oil change.
Motorcraft® SAE 5W-20 Synthetic Blend Motor Oil is a premium-quality passenger car motor oil recommended by Ford Motor Company and meets all warranty requirements.
Although Ford recommends that you use 5W-30 oil in older models, if you own a recent edition, it`s advisable to use 5W-20 oil.
with a 4.6 L Triton V8 engine, you`ll need 6.0 quarts of SAE 5W-20 oil with a Motorcraft FL-820-S oil filter. Ideally, you should change the oil on your F150 every 10,000 miles.
You should replace your F-150`s transmission fluid every 60,000 miles.
Over time, the differential fluid gets dirty, breaks down, and needs to be replaced. So, it is necessary to have your differential serviced regularly. It is recommended to have the differential fluid changed every 40,000 to 60,000 miles.
If you hear grinding, growling, or humming noises that change with your vehicle speed, it may be coming from the transfer case. This could indicate a low fluid level or some mechanical problem such as bad bearings, loose chains or damaged gears.
The transfer case is a gearbox found only in four-wheel drive and some all-wheel drive vehicles that sends drive power from the engine to the front axles. Lubricating fluid inside the transfer case draws heat away from the gears, helping to preserve the life and performance.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Type of oil and when to change
ANSWER : Oil change intervals on your vehicle are determined by the vehicle’s engine oil change monitoring system. A message on your instrument panel will alert you when it is necessary to change the oil. The change interval is based on a computer algorithm and is "duty cycle based". Consequently, the oil change interval is not fixed and will vary depending on personal driving style and drivings conditions. For example, lots of short trips will necessitate a more frequent oil change than if your driving mileage is accumulated under continuous highway driving. An engine computer keeps track of all the required data, processes the data, and then the car’s messaging system lets you know when to change the oil. With some minor caveats, as stated below, synthetic oil can be used at any time and you can switch back and forth between conventional oil and synthetics at any time. Although existing leaks may potentially leak at a somewhat greater rate when using synthetic oils versus purely mineral based (aka, "conventional" oil), the added leakage, if any, is meaningless in most seal locations and in most circumstances. The potential for a leak is due to the smaller size of the molecules in synthetic versus conventional oils. However, synthetic oil cannot possibly cause or otherwise mechanically enlarge a leak. In any event, any "distinction" in leak rate is meaningless simply because if you put synthetic oil in a car and you can see a leak from a seal, that seal was most decidedly leaking anyway with regular oil and so would have to be repaired regardless of the oil "type" you are using.

In your specific case, with a relatively newer car and low miles on the engine, this possibility of a leak probably does not exist at least for a while, although you are getting close to the time frame when just due to rubber aging (over time, not mileage related), leaks will start developing anyway. The bottom line is you can and should use synthetic oil in your circumstances due to its huge advantages in physical properties and potential to lengthen the service life of your engine and even seemingly unrelated parts such as oxygen sensors and the catalytic converter (synthetics don’t have the sulfur and other elemental contaminants that mineral oil has). Full synthetics will be less subject to degradation and evaporation during the oil service interval, too. I would recommend you use "100% synthetic oil". If it were my car I would use the most expensive, highest rated synthetic oil I could find. Changing your oil removes dirt and contaminants and newer cars with all sort of oil actuated mechanisms, such as variable valve timing, need very clean oil. YourMechanic offers oil and filter changes during mobile visits right to your location and you should certainly avail yourself of that service as the cost is lower and the service is much more personalized than at a shop or dealer. If you have additional concerns, don’t hesitate to re-contact YourMechanic.

Problem with transfer case
ANSWER : The two vehicles had different types of transfer case assemblies depending on if it has part time and automatic full time type systems. The differences between the two transfer cases may be more than just the shift motor swap. If you took the transfer case out of a part time suburban vehicle and tried to put it in a full time automatic type system, it may get damaged when driving. Also the internal gearing could be different between the two vehicles but that would be hard to tell. You can take a chance and try it or get the correct one for your vehicle.

Oil change from regular oil to synthetic oil
ANSWER : Using the synthetic oil will not harm your motor or seals in any way as long as the oil weight is the same as recommended by manufacturer. You can keep using this oil until next oil change where you can go back to regular oil if you want.

lost all oil pressure, replaced the oil pump, low oil sensor, oil pressure sensor, oil pan gasket,
ANSWER : The fuel pump will not stay on if you loose oil pressure. This is why it is shutting off. The loss of oil pressure may be from bad crankshaft bearings or camshaft bearings. The engine oil pan should be removed and the oil pump needs to be checked to ensure that you put in the pick up tube seal to the pump and connected the pump to the block. Then remove at least one main bearing cap and inspect the bearings for excessive wear and crankshaft damage. If you need some help with this, consider YourMechanic, as a certified technician can help diagnose the issue with your oil pressure firsthand and help you fix it accordingly.

Low oil pressure light comes on when idle. Check engine light is on as well. Both came on after getting an oil change 3 days ago.
ANSWER : It is possible that they put in the wrong viscosity oil. In rare instances, a defective filter will also cause low pressure. If there is too much oil, it will aerate and cause low pressure. Be sure the oil level is really not above "max". The P2187 code will appear if the oil fill cap is not tight but it will also appear due to a myriad of causes because that code only "generally" identifies a lean running condition. Consequently, numerous parts would have to be tested including the O2 sensor, gas cap seal, manifold air leaks, any vacuum leak anywhere including PCV and EVAP systems, exhaust leaks, and fuel system faults such as failing fuel pump, clogged filter and more. Since the car has relatively low mileage, you would not expect a failed oil pump, although the pressure sensor (or switch) could be bad. However, the occurrence of the oil pressure warning light is quite coincidental to the oil change, thus I would suggest bringing the car back and asking them to redo with a new filter and double check the viscosity of the new oil that they use. If the problem persists after that, you will have to test actual operating oil pressure (at idle for instance) as well as the oil pressure switch. Finally, if the oil pressure warning light comes on continuously, unless the warning circuit itself is malfunctioning, that means the oil pressure is too low to operate the engine without damaging it. Anytime the light comes on for more than literally an instant, you should shut down the car and thus an issue like this obviously has to be repaired.

If you’d like, a YourMechanic certified mechanic can come to your home or place of business to inspect the vehicle and perform an oil pressure light is on inspection to diagnose the vehicle and suggest potential repairs.

which motor oil is best synthetic or regular?
ANSWER : Excessive oil consumption is usually related to piston ring wear or valve guide seals not properly sealing causing engine oil to pass by and be ignited and burnt in the combustion chamber along with the fuel and air mixture. Generally, synthetic oil will not cure a situation like this as this is something that will require a fairly extensive repair job. With that said, there are many different opinions and theories on engine oil. Synthetic vs conventional oil is one of the most debated myths surrounding the topic of oil changes. This will not hurt your engine when switching from synthetic to conventional or vice versa. In fact, Synthetic blend oils are actually a mix of conventional oils and synthetic oils. It is recommended that you use the same oil to top off when needed, giving you the best protection from the oil you have chosen to use in your vehicle. Many people often wonder about the benefits of using synthetic oils. Many synthetic oils are made up of a base oil of approximately 80%, with other additives making up the remaining 20%. The main difference between the molecules in synthetically engineered oils and conventional oils are the uniformity of the molecules. The molecules found in most conventional oils differ in shape, size and impurity. The type of oil that should be used for a specific application depends largely on the driver’s driving habits, the environment in which the car is driven, the mileage on the car’s engine and the limits that the engine may be pushed to. I would recommend having an expert from Your Mechanic come to your home to diagnose your engine oil burning problem as this may be a sign of a bigger problem.

Car losing oil, excessive transfer case fluid
ANSWER : Hello. These two systems are separate so they would not be related. If the transfer case is overfilled then it was either filled too high when it was last serviced or water got into it if you have driven through deep water. As for the oil loss, this is common on this engine. I first check the PCV system to make sure it is fine. If it is then the issue is bad valve stem seals. This is common and allows oil to enter the combustion chamber. The oil burns off without any signs as the catalytic converts get hot enough to burn it without smoking. If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to your home or office to inspect the cause of this issue.

Oil consumption. Burning oil. Oil light turns up on idle.
ANSWER : Hi there, thanks for writing in. The valve stem seals are the most common cause of this on your engine. When they fail, it requires that the cylinder heads be removed and rebuilt to fix it. The piston rings can also cause this but they are not as common. Unfortunately there is not anything, not even heavier oil that will fix this. You will need to have the heads rebuilt.