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I’m a new member with my first post and a couple questions about oil. First off, I’m not a mechanic although I’ve worked on cars since I was 12 and I’m not an engineer, although some friends say I should have been. I just ordered a 2021 longhorn anniversary with eco diesel hoping they have fixed the previous problems. Question 1. Engine oil was changed from 5-30 to 5-40. Don’t understand why they would think 30 weight is heavy enough for a diesel. But they left the 5 weight cold weight alone. Most diesels I’ve had used 15-40. Ask any mechanic or engineer when the most wear on an engine occurs and the answer is the first few seconds of cold startup. Cold start doesn’t only mean freezing temps. It means any ambient temp that the engine has cooled down to over several hours and most of the residual oil on the bearings etc has drained off. Remember, a diesel has very high compression ratio. This one is 16-1. Most gasoline cars are 8-10-1. Diesels have a lot more stress on bearings etc every time a cylinder fires and drives the piston down. A 5 cold weight oil gives very little protection compared to a 15 weight. For the possible gain of a fraction of a mile per gallon fuel saving. I’d like to see at least 10-40. Question 2. Why is the eco diesel oil spec 12991 an API SN? S is for spark which means gasoline engine. Instead of a C spec which stands for compression (diesel) such as CH4 etc. Diesel oil spec is in there for a reason with required additives for soot and several other things. Im concerned Fiat Chrysler is concentrating so hard on fuel mileage, they are ignoring engine wear and therefore engine life expectancy.
 

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5W40 Rotella has done a good job in the Gen 2's. Don't second guess Ram on the oil for the 3d gens. You are in Canada , don't fool around with a thicker oil, especially in winter. Check out my UOA's for the first 100,000 miles with T6. Use the Chrysler spec oil called for in owner's manual. Gen 3 or Gen 2 , would absolutely use only spec oil to protect warrantee. Vern has around 800,000 miles on his Ecodiesel, pretty sure he uses the spec oil. Pretty sure Chrysler is trying to keep these motors from early failures , rather than eking out the last 10th mpg. Believe Ford calls for 5W30 in the 3L Powerstrokes.
 

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Okay - allow me to shed some light - basically any oil that meets MS-12991, meets several other specifications - I have a chart posted on the 3rd Gen Facebook group - it exceeds CK diesel oils significantly in everything except piston scuffing, which isn’t measured - which is irrelevant as that assumes steel Pistons.....

The minimum requirements max out 7/8 rated areas, and are beyond CK in the 8th area, and several of the boutique oils far exceed the minimum requirements.

Now, as for the cold weight - try pouring a 15w oil at 0C, and then a 5W.... the oil pump is able to push the thinner oil into the bearing clearances sooner, meaning less wear on cold starts. The Viscosity Index ensures that it quickly exceeds a 15W at more moderate temperatures, and quality Synthetics (of which several can be found here in a thread listing oils for the 3rd Gen) will actually have better HTHS, and maintain viscosity better than a typical 15w40.

That being said, some people in warmer climates have had success with 15w40, and it’s your truck, your money, do whatever you want.

As for me, I’ll continue to use top quality 5w40s that meet the requirements, and minimize viscosity shift and oil consumption so my DPF will remain happy!
 

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I’m a new member with my first post and a couple questions about oil. First off, I’m not a mechanic although I’ve worked on cars since I was 12 and I’m not an engineer, although some friends say I should have been. I just ordered a 2021 longhorn anniversary with eco diesel hoping they have fixed the previous problems. Question 1. Engine oil was changed from 5-30 to 5-40. Don’t understand why they would think 30 weight is heavy enough for a diesel. But they left the 5 weight cold weight alone. Most diesels I’ve had used 15-40. Ask any mechanic or engineer when the most wear on an engine occurs and the answer is the first few seconds of cold startup. Cold start doesn’t only mean freezing temps. It means any ambient temp that the engine has cooled down to over several hours and most of the residual oil on the bearings etc has drained off. Remember, a diesel has very high compression ratio. This one is 16-1. Most gasoline cars are 8-10-1. Diesels have a lot more stress on bearings etc every time a cylinder fires and drives the piston down. A 5 cold weight oil gives very little protection compared to a 15 weight. For the possible gain of a fraction of a mile per gallon fuel saving. I’d like to see at least 10-40. Question 2. Why is the eco diesel oil spec 12991 an API SN? S is for spark which means gasoline engine. Instead of a C spec which stands for compression (diesel) such as CH4 etc. Diesel oil spec is in there for a reason with required additives for soot and several other things. Im concerned Fiat Chrysler is concentrating so hard on fuel mileage, they are ignoring engine wear and therefore engine life expectancy.
The 30 weight would not be the problem likely the 0 would be the problem as far as 0W-30 goes. Looks like FCA was focused on fuel economy and wanted very light oil to decrease fuel economy loss to drag from heavier oils. The main bearing and Rod bearing oil clearance FCA is shooting for is around .0015 thou. thats tight in my opinion on journals as large as this 3.0l engine .0015 thou is like a feeler gauge like a piece of paper. 2014 on until the new engine I'm thinking 15W-40 might be the best choice. The local Ram dealer said today the new engine is U.S. made not the same as the older Italian made engines just follow recommendations for now the newer engines may be a lot better who knows.
 

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Let’s clear up some bad information -
0W vs 5W vs 10W, etc....
Those are winter ratings based on pour points - they don’t directly correspond to viscosity, though they can trend that way.

In fact - it’s not unusual for a 0W, with its high Viscosity Index - to have a pour point significantly lower than a 5W, but at Freezing (0C), it’s actually thicker (but easier to pump), and at operating temperature it’s identical based on the Viscosity rating (30/40/50) to the higher winter rated oil.

The sacrifice, normally, is volatility. It will vapor more easily,, and tends to potentially have slightly lower HTHS, as well. This means it can burn/consume more oil, particularly if the formulation is not really good.

You see this a lot with shelf oil - where they are built to meet a minimum and profit is king. They are “just good enough” and typically, I wouldn’t recommend using it past the “Severe Duty” interval in the book if you want your vehicle to last. (There are specific exceptions within a product line, there was a German made Castrol Edge that was a premium build for awhile...)

Several better quality oils will basically eliminate the deficiencies seen by using better base stocks, better additive packages, and better formulation. You should be far more concerned with using a better quality product that meets the specifications than using a product outside of the specifications if you are looking to improve your results.
 

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If OP would have bought the diesel GM 3L he’d be complaining on a GM forum about the required DexosD 0w-20 lol
 

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I was going to say the same thing, but Ohio Tech beat me to it. The cold pour number is usually thought of all backward. The LOWER the number the better. You want your oil to flow as quickly as possible upon startup.

Yes, in the old days we used 15W40 in everything because that was all we had. Technology hadn't advanced to the point yet where oils could flow like a 0W when cold but still protect like a 40W when up to operating temp. So we used what we had.

Today, a 0W40 is ideal honestly, but for warranty purposes I'll keep using 5W40. FULL synthetic is a requirement on the Gen 3 EcoDiesel, and API category SN is a requirement also. Ram states that oils meeting material standard 12991 are recommended and so obviously if you can find an oil that meets all three that's your safest bet.
 

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Most people have little to no understanding of hydrodynamic lubrication. They think thicker oil = better protection. They cannot fathom that 20 weight is where some of the most highly stressed engines in the world have settled as being the point of maximum protection. Top Fuel Oil is 70 weight due to dilution. It is under peak loads at the point all the clutches lock in, and is typically thinned to a 20 weight by then.

If OP would have bought the diesel GM 3L he’d be complaining on a GM forum about the required DexosD 0w-20 lol
 

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Im concerned Fiat Chrysler is concentrating so hard on fuel mileage, they are ignoring engine wear and therefore engine life expectancy.
There's no concern. We are seeing UOA reports that show excellent results.
 

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Im concerned Fiat Chrysler is concentrating so hard on fuel mileage, they are ignoring engine wear and therefore engine life expectancy.
Well, the two diesel engines FCA uses in pickup trucks (Cummins 6.7 and VM 3.0) are at the bottom of the barrel in terms of fuel economy. The Cummins engines are now drinking fuel like a big block gas motor with most owners reporting 14-16 MPG in good conditions. And the VM EcoDiesels are averaging 22 MPG according to over a half-million miles of combined real world data from owners, which is 2 MPG below EPA sticker.

GM and Ford are trashing Ram in the fuel economy war. So if FCA is concentrating on fuel mileage, I'd sure hate to see how thirsty these trucks would be if they didn't concentrate on it. :)
 

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The Silverado’s are averaging 22.42 on the Diesel - this in spite of a much higher take rate on the 3.23 gears, and their short ratio being 3.73, instead of 3.92.

They also have a couple fewer V8s who selected the wrong engine, (sub $2/gallon, sub 16 mpg, no tanks above 20) and the average one getting under 22 doesn’t have a picture of his truck lifted sporting oversized A/T or M/Ts.... which is contrary to the EcoDiesel listings on Fuelly....
 

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Well, the two diesel engines FCA uses in pickup trucks (Cummins 6.7 and VM 3.0) are at the bottom of the barrel in terms of fuel economy. The Cummins engines are now drinking fuel like a big block gas motor with most owners reporting 14-16 MPG in good conditions. And the VM EcoDiesels are averaging 22 MPG according to over a half-million miles of combined real world data from owners, which is 2 MPG below EPA sticker.

GM and Ford are trashing Ram in the fuel economy war. So if FCA is concentrating on fuel mileage, I'd sure hate to see how thirsty these trucks would be if they didn't concentrate on it. :)
You must have had your head up your keester when doing due diligence then, or you wouldn't have wound up getting "fleeced" with your Ram purchase. You should have bought the GM instead. Would have saved us all reading your perpetual moaning and groaning about your RAM. Mine is averaging 23.6 as we speak, 50/50 city/hwy with 3.92 gears.
 

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You must have had your head up your keester when doing due diligence then, or you wouldn't have wound up getting "fleeced" with your Ram purchase. You should have bought the GM instead. Would have saved us all reading your perpetual moaning and groaning about your RAM. Mine is averaging 23.6 as we speak, 50/50 city/hwy with 3.92 gears.
I am 3.21, obviously, but my lifetime average is north of 26... I have no tanks less than 22.5 in a really cold winter stretch 100% city with a lot of warmup time to get that... unless I was towing... I have seen just short of 32 on the highway.... and my sticker said 21 city, 29 hwy, 24 combined...
 

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Yep. I can easily get 29 hwy, cruise set to 75 as long as there's no headwind. Considering my previous GMC 4x4 Crew got 17 under the same conditions, and my Tundra 4x4 crew before that got 15, I feel I hit a home run with this Ram ecod. FWIW, I was negotiating on a building to buy the other day, and the owner was driving a new 1/2T duramax, his 2nd one, because the first blew an engine before 10k miles.
 

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I'm thinking 15w-40 might work quite well in this truck, more diesel focused robust additive package maybe sacrificing .5 mpg ?
 

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I'm thinking 15w-40 might work quite well in this truck, more diesel focused robust additive package maybe sacrificing .5 mpg ?
Umm.... it won’t be more diesel focused, nor robust.... literally....

chart 2.jpeg
Here you see C spec requirements....chart 2-
Piston scuffing test is irrelevant to us because we don’t have steel Pistons...

chart 8.jpeg


chart 9.jpeg

Here, you see the minimum requirements for 2 different common MS-12991 oils, with the specifications they meet.

Again, those are minimum requirements - many of the more robust options far exceed those requirements.....

Most shelf diesel oils barely meet the minimum requirements....
 

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Umm.... it won’t be more diesel focused, nor robust.... literally....

View attachment 89269 Here you see C spec requirements....chart 2-
Piston scuffing test is irrelevant to us because we don’t have steel Pistons...

View attachment 89270

View attachment 89271
Here, you see the minimum requirements for 2 different common MS-12991 oils, with the specifications they meet.

Again, those are minimum requirements - many of the more robust options far exceed those requirements.....

Most shelf diesel oils barely meet the minimum requirements....
Then there is reality, 15w-40 synthetic should be over kill IMO my concerns would be the detergency of the 15W-40. 15W-40 typically will release every single tiny metal particle from the block or any place they have settled. If you have taken apart an old engine you would know what I'm talking about, can the oil filter handle very small micron particle's ? Typical 15W - 40 synthetic or non synthetic may be a little harder on engine seals likely because of additives harsher on seals. If I was a fleet operator I would be more inclined to go 15W - 40 synthetic.
 

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Use Red Line Oil? It pretty much acts as a flush, has excellent results on a UOA, and is easy on the seals to boot
 

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Okay - allow me to shed some light - basically any oil that meets MS-12991, meets several other specifications - I have a chart posted on the 3rd Gen Facebook group - it exceeds CK diesel oils significantly in everything except piston scuffing, which isn’t measured - which is irrelevant as that assumes steel Pistons.....

The minimum requirements max out 7/8 rated areas, and are beyond CK in the 8th area, and several of the boutique oils far exceed the minimum requirements.

Now, as for the cold weight - try pouring a 15w oil at 0C, and then a 5W.... the oil pump is able to push the thinner oil into the bearing clearances sooner, meaning less wear on cold starts. The Viscosity Index ensures that it quickly exceeds a 15W at more moderate temperatures, and quality Synthetics (of which several can be found here in a thread listing oils for the 3rd Gen) will actually have better HTHS, and maintain viscosity better than a typical 15w40.

That being said, some people in warmer climates have had success with 15w40, and it’s your truck, your money, do whatever you want.

As for me, I’ll continue to use top quality 5w40s that meet the requirements, and minimize viscosity shift and oil consumption so my DPF will remain happy!
agreed, I am using Triax 5W40, it has a lot more sheer than
the Rotella or the Valvoline
 
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