[Polar Express]

Hi, I did a search and didn't see any discussion about folks that confirmed they do or do NOT use synthetic lube in the diffs.

My manual clearly says I need to use synthetic fluids.... grrrrrrr

I'm just not a fan of paying 3x for a fluid if I don't have to.

Anyone run traditional 'dino' oil in their diffs? I've always used an oil supplement like "Hilton Hy-per Lube" (if there was NO limited slip clutches) to assist with the lubricity of the lubes.

I was thinking of using the 75/140, 'dino' oil with a bit of Hilton in there.... about 1/3 the cost of synthetic lube. I don't haul heavy, but I know the Hilton will thin out the lube a tad, so a 20% ratio should be fine, right???

any feedback gents?

Thanks!
PE

 

[5150eddie]

I run full synthetics front to back for the longevity and better fuel mileage. Switched some time ago and never looked back. Sure it's costlier, but I just feel the benefits are better in the long run....

 

[Hoss50]

I am about to change my new truck to synthetic in the diffs. I put it in my last truck and had zero diff issues in the 200,000 miles on it. I will be running Amsoil 75w90 Severe Gear when I change the diff oil.

 

[CRToney]

Oil is cheap relatively to parts and repairs. Synthetics perform better under cold and hot conditions. You should see better fuel economy with synthetics. I run 0w40 synthetic in my engine year round.

 

[C Schomer]

You should be fine with petro if you aren't working it hard. Semi syn would probably save some $$ too. My experience has been... metal on the magnet is the first thing to look for, as far as wear performance, and it takes UOA to tell if the additives are good. I've had great looking diff lube but the additives were totally shot. I've also had excessive metal on the magnet and the UOA repeatedly said normal cuz the UOA can't see that metal when it's on the magnet and not in the sample. You have to do both til you establish a safe interval. I DO NOT trust UOA alone on gear boxes! Hold your thumb over the hole and put in 5 qts. Craig

 

[johnpr3]

Synthetic can be advantageous in extreme ambient temperature. Otherwise, a good petroleum will work just fine. I have 160k on my diff's since last change. I put on Mag Hy-tec covers, oil, and haven't looked back. The coldest temperatures I've driven in are the low teens with no problems.

 

[steelhead01]

Why waste diesel mpg on a 75w140 when the rig is not used for heavy haul in hot climate? Remember, the viscosity is 140 at highway road temps.

The 11.5" AAM diff is designed for 75w90 100% synthetic, gives slightly better fuel mpg than a crude oil based lube and far more protection to a very expensive rear end. That rear end often outlasts a Cummins when correct lube oil is used in it.

Conventional 75w90 crude oil base stock lube is rare. Only ones making it now is Valvoline. Difficult to find. Why waste the effort chasing all over. There are lots of cheap 80w90 convention crude oil base stock lubes on the market that I would only trust in an old beater.

Go full 100% synthetic and save the greasy kids stuff of having to change every 25k miles with crude base stock cheap stuff. Can easily go 100k on full 100% syn base stock lubes.
If it's a price point problem go to Walmart.

http://www.walmart.com/ip/MAG-1-MG759FPL-Full-Synthetic-Motor-Oil-1-Qt.-75W-90/40881180

Mobil 1 75w90 100% synthetic is often on sale under $10 qt.

A full synthetic needs no expensive snake oil wonder juice out of a bottle.

With a 100% synthetic lube in it, you won't have to worry on a heavy tow for a friend in 100d F heat in summer pulling W bound on the N. Cascades

Just make sure whatever you put in is rated API Service GL-5 EP
Do it right and save money in the long term.

 

[Gray Rider]

I was a dodge service manager for 9 of my 24 years as service manager and I encourage you to put the proper specification fluids in your truck, especially if you use the truck as it was designed. If you do not tow or carry heavy loads you can get away with it. But if you tow or carry the loads the truck was designed for you run a strong chance of buying a diff later down the road, especially if you are in hot climates.

If your truck is under warranty you want to use the correct fluids so you do not give the manufacturer an excuse not to pay for the repairs. From a service manager perspective Dodge is the worst manufacturer to deal with. They make the dealer jump through a lot of hoops to get approval for warranty repairs. Even if the Dodge district rep approves it the dealer may still have the entire repair charged back if Dodge can find an excuse to not pay for the repairs that have already been performed once the parts have been returned to Dodge. I know a dealer that will not install an engine until the claim is paid. They have a loaner truck they give the customer while they jump through the hoops to get it approved and paid. Dodge is bad about changing their mind after approving a repair and leaving the dealer stuck with the bill.

So if your truck is still under the powertrain warranty PLEASE use the correct fluids in your vehicle so no one has to explain how much it will cost to repair your truck when it could have been covered under warranty. Believe me no one at the dealership wants to say no but they have no choice.

 

[johnpr3]

I was a dodge service manager for 9 of my 24 years as service manager and I encourage you to put the proper specification fluids in your truck, especially if you use the truck as it was designed. If you do not tow or carry heavy loads you can get away with it. But if you tow or carry the loads the truck was designed for you run a strong chance of buying a diff later down the road, especially if you are in hot climates.

If your truck is under warranty you want to use the correct fluids so you do not give the manufacturer an excuse not to pay for the repairs. From a service manager perspective Dodge is the worst manufacturer to deal with. They make the dealer jump through a lot of hoops to get approval for warranty repairs. Even if the Dodge district rep approves it the dealer may still have the entire repair charged back if Dodge can find an excuse to not pay for the repairs that have already been performed once the parts have been returned to Dodge. I know a dealer that will not install an engine until the claim is paid. They have a loaner truck they give the customer while they jump through the hoops to get it approved and paid. Dodge is bad about changing their mind after approving a repair and leaving the dealer stuck with the bill.

So if your truck is still under the powertrain warranty PLEASE use the correct fluids in your vehicle so no one has to explain how much it will cost to repair your truck when it could have been covered under warranty. Believe me no one at the dealership wants to say no but they have no choice.

I was always curious how the Dealer would know which oil you used. Do they take a sample or go by the color? Does the customer have to prove what was in their diffs?

 

[lhedrick]

But if you tow or carry the loads the truck was designed for you run a strong chance of buying a diff later down the road, especially if you are in hot climates.

From a service manager perspective Dodge is the worst manufacturer to deal with.

Well, you said it not me.

With the front suspending on my RAM I hardly trust working it empty let alone "what it was designed for".

The choice of differential lubricants is the least of the problems with this truck.

 

[TexasRed5.9]

Every vehicle I own has synthetic purple gear oil in it. It may cost a little more, but after spending a few years as a heavy truck mechanic I have seen what cheap gear oil can do to a differential.

 

[lhedrick]

Every vehicle I own has synthetic purple gear oil in it. It may cost a little more, but after spending a few years as a heavy truck mechanic I have seen what cheap gear oil can do to a differential.

Can you describe what you saw. Was it visible ware on ring or pinion gears, metal in the oil?

If using non-synthetic what change interval would you use?

What I like most about synthetic lubricants are their ability to function at start up in cold temps. Big difference between 10W30 synthetic oil and regular when you pour it out of the bottle when its 10 degrees in the winter. Am I correct in thinking it's the same with gear oil?

 

[MichaelJT]

It's foolish to try to save a few pennies on lubricants. Good oil and grease is the best money you will ever spend on a vehicle. I don't care if it costs twice as much, I want the best I can get. That extra money you spend today may very well pay off on the failure you DON'T have when you are out on the back side of beyond, miles from any parts store, tow truck or mechanic.
Take a look at the expression on the face of the next person you see broken down alongside the highway. Do you really want to be that guy?

 

[lhedrick]

How do we know a more expensive lubricant is any different then a lower priced brand or just marketing hype and a large advertising budget.

In many cases different brands are the same commodity in a different package. I will pay more for quality but I need to have some proof. Grease and gear oil has been around for a long time and it's always worked. WalMart does not make synthetic gear oil so it's got to be some name brand in their own plastic container. Could it be Mobile 1 at a lower price?

 

[Roadmedic]

How do we know a more expensive lubricant is any different then a lower priced brand or just marketing hype and a large advertising budget.

In many cases different brands are the same commodity in a different package. I will pay more for quality but I need to have some proof. Grease and gear oil has been around for a long time and it's always worked. WalMart does not make synthetic gear oil so it's got to be some name brand in their own plastic container. Could it be Mobile 1 at a lower price?

These threads lead to one saying one brand is better and another disagreeing.

Use whatever you want.

I know many do not like the brand I use. I run Royal Purple synthetic in the rear end. I run the fluid for 50,000 miles and then drain and do again.

Others like Amsoil. Use the best quality you like and live with it.

 

[Gray Rider]

I was always curious how the Dealer would know which oil you used. Do they take a sample or go by the color? Does the customer have to prove what was in their diffs?

They can tell by both an oil sample and from the customer's maintenance records.

If the failure occurs before the first scheduled maintenance interval they assume it is the fluid they installed in the truck. If it is past the published interval the customer must provide maintenance records that indicate the type of oil used.

If a customer maintains their vehicle themselves they need to keep the sales receipt when the oil was purchased.

No maintenance receipts showing the correct oil was used = declined repair.

These decisions are not made at the dealer level but at a manufacturer call center. Too bad they do not have to face the customer.

 

[dieselenthusiast]

I use Amsoil Severe Gear 75W-90 in the front and rear diffs. Both diffs have an aluminum Mag-Hytec cover with cooling fins, a magnetic dipstick and hold significantly more fluid. I haven't taken an oil analysis to determine when they might need to be changed. I do, however, routinely change them at 40,000 mile intervals by doing a quick and easy drain and fill. I would guess that 70% of the miles are towing light loads (6,000 lbs.).