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Please explain this 6.7 oil question

Will_T

Will_T

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I am not due for the first oil change yet but will get close to a year in 3 months or so and will be at probably only about 5,000 miles max. So future oil changes will likely occur once a year in March. I see the Ram call for 10W-30 in normal temps and 5W-40 in cold. But I have seen a few people, like @Brutal_HO this morning say 5W-40 for hot temps. In other places I have seen the 5W-40 for towing only trucks. I am confused as to why if 5W-40 is for cold temps, it would also be for towing and hot temps? Obviously, I don't understand this well, but any explanation would be appreciated. Thanks.

If I will be running the oil for a year March to March, 90% of miles for towing, temps between 30 degrees and 90 degrees for @75% of the time. The remaining 25% of towing time would be 90 or above, maybe briefly as high as 110. The other limitation is that the oil change will be at the dealer so I may be limited to what they will provide? I may only use the dealer for the first oil and filters change if I can find someone local to help be the next time after that to make sure I do it right. But it is probably unlikely that will happen as all the folks I know that do their own oil and filter changes on these trucks live very far away from me.
 
I've been running 10w30 syn in the texas and colorado climate with no issues... there has been some back and forth, along with a tsb, regarding thos topic.
 
Will_T said:
I am not due for the first oil change yet but will get close to a year in 3 months or so and will be at probably only about 5,000 miles max. So future oil changes will likely occur once a year in March. I see the Ram call for 10W-30 in normal temps and 5W-40 in cold. But I have seen a few people, like @Brutal_HO this morning say 5W-40 for hot temps. In other places I have seen the 5W-40 for towing only trucks. I am confused as to why if 5W-40 is for cold temps, it would also be for towing and hot temps? Obviously, I don't understand this well, but any explanation would be appreciated. Thanks.

If I will be running the oil for a year March to March, 90% of miles for towing, temps between 30 degrees and 90 degrees for @75% of the time. The remaining 25% of towing time would be 90 or above, maybe briefly as high as 110. The other limitation is that the oil change will be at the dealer so I may be limited to what they will provide? I may only use the dealer for the first oil and filters change if I can find someone local to help be the next time after that to make sure I do it right. But it is probably unlikely that will happen as all the folks I know that do their own oil and filter changes on these trucks live very far away from me.
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10w-30 is good for all temps above 0F. 5w-40 synthetic is good for all temps. Hotter ambient air temps makes no difference to either of those two oils, because at normal operating temperatures, the oil will always be above 200F, which is hotter than any ambient air temps you’ll be in.
 
Thanks. When people here just say "5W-40" is the reference always to full synthetic? Or is there both synthetic and non-synthetic 5W-40 being referred to?
 
Will_T said:
Thanks. When people here just say "5W-40" is the reference always to full synthetic? Or is there both synthetic and non-synthetic 5W-40 being referred to?
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I can’t speak for others, but synthetic is specifically called for 5w-40 in the manual. The 10w-30 can be dino.
 
Jimmy07 said:
10w-30 is good for all temps above 0F. 5w-40 synthetic is good for all temps. Hotter ambient air temps makes no difference to either of those two oils, because at normal operating temperatures, the oil will always be above 200F, which is hotter than any ambient air temps you’ll be in.
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Given this, which would be preferred, 10W-30 or 5W-40, if always above 0F and almost always towing? Or does it truly not matter at all? And do the dealers generally have both?
 
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Will_T said:
Given this, which would be preferred if always above 0F and almost always towing? Or does it truly not matter at all? And do the dealers generally have both?
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You’ll get responses all over the spectrum on this one, from people who only buy the most expensive oil known to man, to people that only use such n such brand because their great grandpa used to use it in his weedwackers, to guys like me- I just use the cheapest oil available at the time that meets the specs. Given your situation, you’d be fine with the 10-30, even towing mostly. I wouldn’t stretch it to the full 15,000 interval with always towing, as the heavier duty cycle breaks it down quicker.
The dealers should have both in stock.
 
Thanks @Jimmy07 That answers it. At a year I will still be well under 15,000 but in the future if mileage is higher, I will do as you suggest.
 
Really depends in what you do with the truck, for your temp range you would be good with 10w30 but if you haul heavy or work it hard alot then id recommend 5w40
 
I run Shell Rotella 5W40+ Penzoil 0W20
5W is easier at cold startup than a 10W, 15W would not even work well where I live, its too cold here in the winter.
W40 is thicker than a W30 at high temps. I would rather like a W30 than a W40 because it does not get super hot where I live and thick oil is just a drag in the engine.
My favorite Diesel oil would be 5W30 or 0W25 or something but that does not exist.
I added 3qt 0W20 to the 2.5 Gallons of 5W40, so that I end up with a 3W35 or something like it. Easier cold start ups and reasonably thin at higher oil temps for better MPG.
Usually I add a shot of ZDDP for wear reduction.
 
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