Change to Synthetic Oil in Diffs-Seal Leaks?

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A HD truck mechanic whose opinion is usually reliable told me that changing from regular gear lube to synthetic in the differentials can cause the axle seals to leak. I know axle seal leaks occur for other reasons, such as sitting in storage for too long, but I had never heard of this one. I was considering going to synthetic in the differentials on the next change. Anyone heard of this happening?


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'97 2500 CC 4x4 5spd 3. 54LSD all stock except K&N Air, EGT&Boost Guages - next Psychotty & 4" exhaust

 

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I changed at 30K and had no problems with the axle seals but the differential seal started to leak. I bought a new seal and was going to replace when the weather improved. The leak sealed itself. The tailshaft seal on the transmission started leaking but has slowed down some since it warmed up. I haven't got around to changing this one but will.

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98. 5 ISB 2500HD 4X4 SLT QC, 3. 54 forest green/camel leather, 5 spd. hood weather bra, cobra CB, Westech boost & pyro, Geno "A" pod, Dee Zee brds. Grover air horns, toaster LED's, HD light lens covers, bug deflector, J&J mud flaps, back up alarm, K&N, Guidon fiberglass tonneau, Ventvisors, Fuel door LED's, X-mission fltr. Fosgate/Clarion system, ABS, trailer tow, Aux rear suspension, factory clearance lamps, sliding rear window, Michelin LT265/75R16 LTX AT, RamZerks, 24' Reinell with tandem trailer. Ring removed.
"Quad-a-Saurus"

 

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30 years ago, maybe. This is a myth. High quality synthetics, like Amsoil or Mobil 1, do not cause leaks, period.
If you do not have a leak now, you won't when you change.
Overall, the country is still greatly misinformed about synthetics, give them some time yet.

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GENE

1997 BOMBed 4x4
NRA Member
GLTDR Member
LIC-ROC Member

[This message has been edited by MGM (edited 07-03-2000). ]

 

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Synthetics are actually help prevent seal leaks. I rear seal leaks on the factory fill. Changed to synthetics and no leaks in the last 130K.

jjw
ND

 

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I've been told to look for (gl-5) additive.
Not all lubs. have this. I believe it is a seal conditioner.
Has anyone else heard,or read about(gl-5)?
I changed to Shell syn. diff. oils at 20k. with no problems.

 

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I've used synthetic oil in all my diffs for the last 23 years - Never had a leak. IMO - If it leaks due to synthetic it needed to be replaced anyway...

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2001 HO 6 speed Regular Cab SLT 4x4 3. 54 anti spin 2500. Used for the daily grind and sneaking away to some secret Baja beaches toting a cabover

 

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Jack, I quote from the Dodge manual that came with my 1999 2500 Cummins w/5spd. "... reduce the potential for rear axle overheating by replacing the rear axle lubricant with an SAE75W-140 synthetic gear lubricant. " pg. 149. The NV4500 comes from the factory with Castrol Syntec in it. I have synthetics (Amsoil) in all my vehicles and have had no problems with leaks. A leak probably means the seal was ready to go anyway.

Regards

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J. Hart

 

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scooter: GL-5 is the additive package. The main diffrence is GL-5 has alot more extrem(sp) pressure additives than GL-4. It wouldn't surprise me if GL-5 has more seal conditioner than GL-4.

 

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Thanks guys. I guess old myths die hard. I will be switching to synthetics in my differentials soon. #ad

PS My handle is JackTar but I'm Pete.

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'97 2500 CC 4x4 5spd 3. 54LSD all stock except K&N Air, EGT&Boost Guages - next Psychotty & 4" exhaust

 

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I bought my '97 used with 20k miles on it. One of the first things I did was to get a Mag Tech rear cover, but before I installed it, I contacted Dana to ask about syn. gear lube. Their answer -- by all means use it, wish DC installed it at the factory!!