6.7L Cummins Forum

I have a 09' 3500 DRW with 9.25" AAM front and 10.25" AAM rear axles (both open) I have planned on using Amsoil 75W-90 Severe gear in both. What do you think?

They have a good product but I just use Mobil 1 since I can get it at Walmart.

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2007.5 Dodge Ram 3500 HD,QC, 6.7L Cummins, 6speed Auto, 4X4, Bighorn Edition.
Click for installs: Carr Steps PML Diff Cover Edge Juice with Attitude Volant Intake Hankook ATM RF10

I was using all Mobil products in my truck until last summer (90,000 KMs) when I switched to Amsoil. Except for some availability issues, I had no problems with the Mobil products. I had in fact used them for years.
The Amsoil distributor is very close to where I work and the cost of the engine oil is less than the Mobil Delvac 1. I am using Amsoil CJ-4 5w40 oil and Extreme Gear 75-140 in the diffs. Towed my travel trailer about 10,000 KMs since changing to Amsoil (now over 110,000 KMs on the truck), with no problems.
With the exception of transmission fluid, I am going to switch my wife's diesel Grand Cherokee and our other vehicles over to Amsoil as well. Might as well buy all the oil in one place.

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2007 Ram 2500 QC 4x4 SLT TRX4-Offroad 6.7L Automatic. '08 Jeep WK 3.0L diesel-wife's DD.
1998 Jeep ZJ 4.0L Automatic Selectrac-project for our son. '98 Jeep XJ-my wife's former DD.
1965 Dodge Polara 880 Convertible 383 Automatic.

I would use Amsoil but I live out in the Country, work nights and Walmart is open 24/7 so it works for me.

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2007.5 Dodge Ram 3500 HD,QC, 6.7L Cummins, 6speed Auto, 4X4, Bighorn Edition.
Click for installs: Carr Steps PML Diff Cover Edge Juice with Attitude Volant Intake Hankook ATM RF10

Well now here is what I was recently told by the idiots @ Dallas Dodge (Georgia). That the mfg. Now recommends that the rearend be flushed in the heavy duties(2010 Dodge 4500 mine) every 15k miles or it will void the warranty. I welcome any input on this matter. Because it sounds like some Hella BS.

I noticed that writing in the maint. manual too. I am not an advocate of that short of an interval esp. with synthetic oils in gear cases. I did change mine at the 15K mark and found not unusual conditions. I am over 50K now and will be changing them here when my traveling slows down some. I use Royal Purple 75w - 140, it has been good to me in the past.

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07.5 3500 Quad, SRW, 4X4, Laramie, Leathered, Dark Metallic Gray, 6.7, 68RFE, 20K Reese, Ride Rite's, 2 Viair air compressors, Bully steps, Kleinn Locomotive air horns (5 in all), Billet polished locking fuel door, 'A' pillar mount Auto Meter Pryo, PML X-deep trans pan
06 Durango 285 RL 5'er Lifted by KZ