diff fluid changes, front and rear

dirtydog · #1 12-01-2008, 01:34 PM

I am going to change my differential fluid in my rear diff on my '08 Ram. I have 2600miles on it and have done a bit of hauling and towing. I am switching to synthetic. Should I wait for the front change since I have not used 4x4 mode? I know I will be using 4x4 a nit this winter and I'm thinking I should wait until after winter to changes the fluid since it will still need some breaking in. What do you guys think? Smae time change or should I wait since ithasn't had but passive wear?

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HammerZ71 · #2 12-01-2008, 02:04 PM

Unless Chrysler has started "cheaping out" your '08 should have been shipped with synthetic in it. My '04 had synthetic in the front & rear from the factory (at least that's what a golf buddy who's the service mgr. at my local dealer told me a couple years ago).

If that's the case, I'd leave both alone until I had 15k miles on the truck. My personal MO on all the trucks I've had has been to do both at 15k to get a good look inside & at the magnets, then if all looked good, fill with synthetic and do them at 30k intervals thereafter. But that's just me, I'd never fault anyone for changing any lubricants more often than specs call for...

Right now, I have synthetic in the front and dino in the rear (yeah, I know sounds stupid, but the Auburn Gear LSD specifically calls to NOT use synthetic - I've even called Auburn to verify and got into it pretty good at a booth at a truck show with a rep, they'll void the warranty if they find synthetic was used

). So in my truck, it gets dino (specifically Lucas) oil at 15k in the rear and synthetic in the front every 30k...

dirtydog · #3 12-01-2008, 02:27 PM

OK then I will wait until after winter to change both then. That's easy enough for me! It is just unusually warm today and I figured I'd do it now than freeze myself. I'll check into the owners manual if indeed it has synthetic. Thanks

HammerZ71 · #4 12-01-2008, 02:37 PM

'dog, I just got an email back from my buddy at the stealership, according to him all the trucks ship with synthetic in the diffs since Chrysler switched from Dana to AAM axles. I'd still verify it yourself, you know how "knowledgeable" dealerships are, but I figure I'd pass it along to you...

meridian · #5 12-01-2008, 02:50 PM

If it has clutch plates inside I wouldn't use synthetic as it causes the clutches to slip and wear out. Point in question, on my Suzuki 1300 hayabusa I use semi synthetic. If I use fully synthetic (and I have tried) the clutch will slip and eventually burn out trashing my engine with worn friction material. Stick to the manufacturers lube and change it as often as they specify.

dirtydog · #6 12-01-2008, 06:06 PM

Thanks Hammer I appreciate that.

LinerJoe · #7 12-01-2008, 07:05 PM

Quote:

Originally Posted by meridian

If it has clutch plates inside I wouldn't use synthetic as it causes the clutches to slip and wear out. Point in question, on my Suzuki 1300 hayabusa I use semi synthetic. If I use fully synthetic (and I have tried) the clutch will slip and eventually burn out trashing my engine with worn friction material. Stick to the manufacturers lube and change it as often as they specify.

Are you sure the full synthetic you used did NOT have the friction modifiers in it? The modifier will cause your clutch to slip.

joe

meridian · #8 12-01-2008, 07:14 PM

No friction modifiers as M/C oils don't use them because of the wet clutches. I tried Silkolene fully synthetic and it made my clutch slip even though Hayabusa's have a sort of lock up clutch! I went back to Silkolene semi synthetic and it worked fine. I wouldn't use synthetic in a slipper diff that uses friction clutches for the same reason.

dirtydog · #9 12-01-2008, 07:14 PM

Quote:

Originally Posted by LinerJoe

Are you sure the full synthetic you used did NOT have the friction modifiers in it? The modifier will cause your clutch to slip.

joe

I'm pretty sure you have that backwards. Friction modifier is to enduce friction so the clutch plates grab one another.
I think he just installed Full synthetic and didn't add modifier which will cause slipping and chatter. More so slipping as chatter can result from too much modifier.
I have never heard of Full synthetic being bad for anything. Friction modifier on the other hand is bad for seals, wear, causes oil to break down faster. That's why too much modifier is bad along with too much plate grip.

meridian · #10 12-01-2008, 07:19 PM

Friction modifiers are added to reduce friction. They are added to stop surfaces touching each other. Hence why they burn out wet clutches as it makes them slip, overheat and burn out.