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I have almost 20 K on my engine and have 5" TBE and EGR delted, I want to start using synthetic oil and was wondering if I need to run low ash oil since I have done away with all this nonsense now. I have considered royal purple and amosil as possible oils. Is anybody running these oils and what mileage would you start with the synthetic? I feel my motor still needs more break in time before I do this. With synthetic at what intervals would you change your oil?
 

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I have been around diesels all my life as we had a trucking company growing up and I am now a diesel mechanic. I always heard that you shouldnt run synthetic before 50,000 miles. I dont have any tecnical data to back it up, but it makes sense to me. I wouldnt run it before then. Chris
 

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Talk to Duluth Diesel here on the forums. He knows his stuff. I am running amsoil synthetic in mine and i switched to it with the bypass setup at 18k. So far no issues. I have not seen any MPG increases but no decreases either. only been 2000 miles so no report as to longevity.
 

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I've got a thousand dollars worth of Amsoil sitting in my garage, I'm gunna wait till 20k for the engine and I'll wait till I get my new torque converter for the tranny. I'll switch to Amsoil in the diffs at 15k, I've only got 4k so far. It's kind a hard to justify driving my oil burner cause the wife's in the middle east, and keep driving her bug, . At least it's got a turbo:rof, still kind of though.
 

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Oh yeah I forgot to mention the pink seats and the hippie flowers. It's still not as bad as a Prius.
 

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I have been around diesels all my life as we had a trucking company growing up and I am now a diesel mechanic. I always heard that you shouldnt run synthetic before 50,000 miles. I dont have any tecnical data to back it up, but it makes sense to me. I wouldnt run it before then. Chris
My Volkswagen diesel came from the factory filled with synthetic oil. In fact, a very specific synthetic oil is required. But then, I suppose it's a different animal. The Cummins owner's manual says 5W40 oil is OK to use, and I've never seen that particular weight in a nonsynthetic oil.
 

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I use syn for break in on good motors...
 

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Amsoil make a 5-40, for the new motors, I use the amsoil 15-40 in my 5.9 , changed over at 20 thousand miles, I read on the cummin`s site that you shouldnt use synthetic before that mileage, Ive got it in my diff and trany, all works great for me, over 45 thou now.
 

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i switched to royal purple at 3000 miles, no problems.
 

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I am running schaeffer's 5w-40 in the engine. It is cj-4 rated. Scaeffer's 75w-90 syn. in diffs. and shaeffer's syn atf+4 in transfer case. Still waiting to do the tranny.
 

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I switched mine over to amsoil syntheitc 5w-40 at 8500. I have been running syntheitc in my 2000 model and it has 450,627 miles and no problems.
 

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I have almost 20 K on my engine and have 5" TBE and EGR delted, I want to start using synthetic oil and was wondering if I need to run low ash oil since I have done away with all this nonsense now. I have considered royal purple and amosil as possible oils. Is anybody running these oils and what mileage would you start with the synthetic? I feel my motor still needs more break in time before I do this. With synthetic at what intervals would you change your oil?
AMSOIL DEO CJ-4 5W40 meets the specifications for your 6.7. As Cummins states, you are fine to switch your engine over at your first service interval, which is usually 5k or 7.5k miles. You intervals with AMSOIL DEO and an AMSOIL filter would be 1 year or 15k miles.

-Chuck
 

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my dealer said that synthetic will take out the TEFLON :butt: seals 08 6.7 long:$:-bed mega cab everything else stock:CRY:
He's full of it.

It will not hurt anything, it only will help.:thumbsup
 

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He's full of it.

It will not hurt anything, it only will help.:thumbsup
Yep, he doesn't know what he's talking about. A top quality synthetic oil will protect better and meets/exceeds all the specs for these engines. Not all synthetics are created equal. Most are just Group III oils, not a Group IV true synthetic.

-Chuck
 
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