Any1 run 10w30 in their diesels?
That's the oil that's endorsed by Cummins. I've never heard if that's what they fill the engines with at the factory, and have never assumed it is. It's quite possible the initial fill is with some sort of a break in oil.
Run either a 15w40 or a 5w40 in your truck, thats what is recommended by the manufacturer. If they wanted you to use 10w30 theywould have added it to the specs.
But it is your engine and your money.
But it is your engine and your money.
10w/30 doesn't make sense as a cold weather approach because you are affecting the hot viscosity more than the cold. Dropping the cold number by 5 and the hot number by 10 gives a slightly better start, but thinner running hot oil than the standard 15w/40. The engine runs at basically same temperature after it warms up no matter what the ambient temperature. 5w/40 gives you more cold flow starting protection while maintaining normal hot running viscosity. The only scenario I would envision using a 30 weight oil of any kind is short trip driving in Alaska.
You're probably gonna want to break in that new engine with conventional 15w40 oil. Pull heavy and hard for 15K then do the switch to Amsoil 15w40 Diesel & Marine and never look back. IMHO, no matter if its a new engine from factory or freshly rebuilt, the break in is important.
I am doing this procedure with my '07 (just need to drive it more). Synthetic right off the hop won't allow for proper seating of rings and such. Get her hot a few times in the first 15K then switch. I think I mentioned to you in another thread, myself and buddies run 15w40 year round no matter what the temp is - we have found ourselves being unable to plug in at hunting camp - no issues.
i agree with Festus, except for one thing.i too run amsoil, and love it, i run it in everything i own, unless its a leaker, its gets the off the shelve oil.
as for sythetics for break in, i am not totally sold on that any more. i have been an amsoil dealer for about 16 yrs, and have always told people to never buy syth oil for break in. why do the car manufactures use syth right from the factory?corvette, syth, performance car use the stuff right off the line. i have a friend in the racing industry, F1, they use syth, new motors or not.they run the tests, what works what don't in their enviroment, which is not the same as every day driving.oil serves a couple of purposes really, it protects moving parts, leaving a film between them,which is lubrication, stops rusting of internal parts, and suspends dirt and particles to be filtered through the oil filter, or filters as some might run.whats the difference between an normal petrolium base stock oil, and a syth base stock oil when it comes to these aspects and break in? other then the syth base stocks won't break down as fast, and the viscosity numbers are more consistant. i could be wrong, and i don't have any lab testing to back me up, but i do know from past experiences that i have had good luck with syth oils, not all are created equal by the way, and anythign i bought new, i drove it the way i would normally,with lots of rpms.i was always told never to hold a certain rpm for a long time while in break in, which i never did, you can speed up some and then slow back down.
as for sythetics for break in, i am not totally sold on that any more. i have been an amsoil dealer for about 16 yrs, and have always told people to never buy syth oil for break in. why do the car manufactures use syth right from the factory?corvette, syth, performance car use the stuff right off the line. i have a friend in the racing industry, F1, they use syth, new motors or not.they run the tests, what works what don't in their enviroment, which is not the same as every day driving.oil serves a couple of purposes really, it protects moving parts, leaving a film between them,which is lubrication, stops rusting of internal parts, and suspends dirt and particles to be filtered through the oil filter, or filters as some might run.whats the difference between an normal petrolium base stock oil, and a syth base stock oil when it comes to these aspects and break in? other then the syth base stocks won't break down as fast, and the viscosity numbers are more consistant. i could be wrong, and i don't have any lab testing to back me up, but i do know from past experiences that i have had good luck with syth oils, not all are created equal by the way, and anythign i bought new, i drove it the way i would normally,with lots of rpms.i was always told never to hold a certain rpm for a long time while in break in, which i never did, you can speed up some and then slow back down.
Don't use synthetics because they are too slippery for break-in! 

Don't use the new CJ-rated oils or your engine will blow up in a million pieces!

Don't use anything but stock parts purchased from the dealer or you'll die!!


Don't use the new CJ-rated oils or your engine will blow up in a million pieces!


Don't use anything but stock parts purchased from the dealer or you'll die!!

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