RAM 2500 Diesel lifter noise

[vjjack04]

Ramsare4real, I had Shell Rotella synthetic, now I have Mobil 1 Delvac full synthetic 5W-40. Just seems to me that there must be something very particular concerning the 15w-40 oil problem it has all the API rating and other qualifications. Would seem that as soon as the truck is at operating temp, the oil operating range would all be evened out, so to speak.

 

[Choupique]

15w40 doesn't have the right cold flow properties for hydraulic roller lifter engines. Simple as that. If you think about how a hydraulic lifter works, it's not hard to imagine poor-flowing oil not cooperating with them.

 

[vjjack04]

Well heck, we are on the topic. I've read a lot about oil and am no expert (maybe some of you are) so I'd be interested to know more about the details of "cold flow properties" as related to differing oils and why it affects the Cummins. I understand the oil SAE viscosity ratings and have researched information related to oils and operating temperatures vice the ambient temp at start up. Plus the "index improvers" added to thicken the oils. Just seems that if you can run 10W-30 and or 5W-40 that 15W-40 is only a slight deviation (oil runs very slightly slower at initial start up than 10W). I understand how hydraulic roller lifters work as they have been in gas engines for many years. And some of those engines run 15W or more with no problem. This is an interesting issue and the Cummins engines with roller lifters must be somewhat unique for this issue to be such a big deal. Now considering all this if the manufacturer says run a specific oil and includes a caution, then that's what I'll do (my previous error not withstanding).

 

[06 Dodge]

Most likely not the best way to explain this but it comes down to the fact is that 15w oil is thicker then the specked 10w, with 15w oil being thicker it does not allow proper oil flow (aka good lubrication) to the roller bearings and with poor oil flow happens...

 

[Choupique]

None of the diesel engines in pickup trucks spec 15w40 as far as I am aware. Getting into lifter design is not something I've worked on before, but I imagine the clearances have to be figured out around a relatively narrow viscosity and pressure range. You can probably design the lifter to function with basically any oil or pressure but it'll likely not work well outside of what it was designed and tested for. The options are probably get it right for a specific oil or make it sloppy and just burn oil, which obviously doesn't fly these days.

 

[mtnrider]

None of the diesel engines in pickup trucks spec 15w40 as far as I am aware. Getting into lifter design is not something I've worked on before, but I imagine the clearances have to be figured out around a relatively narrow viscosity and pressure range. You can probably design the lifter to function with basically any oil or pressure but it'll likely not work well outside of what it was designed and tested for. The options are probably get it right for a specific oil or make it sloppy and just burn oil, which obviously doesn't fly these days.

Pre 2019 Ram cummins spec 15w-40. (hence the confusion and why people still are putting 15-40 in the new trucks, it was the correct oil for many many years)

.

 

[vjjack04]

Folks, thanks. This is interesting conversation. I understand that the XXW oil with the lower number at low or no temperature in the engine is "lighter" (so to speak) and will flow better when cold, but as soon as up to and about operating temperature (looks like between 185 deg and 215 within about 5-10 miles down the road [Arizona summer start up at 90 degrees]) the additives in the oil make it perform at the XX heavier "weight". So the engine spends most of its time operating at the average temperature with oil more on the 30-40 "weight" side. It would seem that the hydraulic lifter orifice(s) or valvetrain oil path, is extremely sensitive during very early operation only...anyway. I think we beat this dead. I have 5W-40 in it and I asked a mechanic friend today to listen to my engine while idling and neither of us could hear tapping....although it does do it, sometimes.

 

[ramsare4real]

Ramsare4real, I had Shell Rotella synthetic, now I have Mobil 1 Delvac full synthetic 5W-40. Just seems to me that there must be something very particular concerning the 15w-40 oil problem it has all the API rating and other qualifications. Would seem that as soon as the truck is at operating temp, the oil operating range would all be evened out, so to speak.

Both, 5w and 15w-40 are 40 grade oils. Unless you're starting your truck at below -20F, there will be no meaningful difference in pumpability between them.
Deposits formations has nothing to do with Winter rating, or viscosity for that matter.

 

[Choupique]

Dude, it matters. There's a reason hydraulic lifter engines always call for 0w, 5w or 10w oils. Cold flow characteristics are very important and a very different in 5w-40 synthetics vs 15w40 conventional. Flat tappet engines do not care, hydraulic lifter engines do.

 

[18CrewDually]

Both, 5w and 15w-40 are 40 grade oils. Unless you're starting your truck at below -20F, there will be no meaningful difference in pumpability between them.
Deposits formations has nothing to do with Winter rating, or viscosity for that matter.

Not sure if its a "pumpability" issue as much as a dispersion issue.
At low temps a 5w oil disperses (splashes) to lube valve train alot easier than 15w.
The 2022s that I heard of having issues start around 60-80k with a tap then goes south from there. Starts in the rockers and or lifters. Run it long enough you'll need a cam, lifters, rockers, and pushrods. Usually by right outside of warranty.

 

[ramsare4real]

Dude, it does not.

Dude, it matters. There's a reason hydraulic lifter engines always call for 0w, 5w or 10w oils. Cold flow characteristics are very important and a very different in 5w-40 synthetics vs 15w40 conventional. Flat tappet engines do not care, hydraulic lifter engines do.

At 40 C, there are no meaningful differences in "cold flow" (pumpability) between those, regardless of chemistry (conventional vs. synthetic).
The difference will be noticeable at the minimum temp each one is suitable for. A 0W-40 will be a LOT thicker at 0 F than a 15W-40 is at 40 F, yet is pumpable at - 35 F, while the latter is not.
Again, deposits formation has no bearing on viscosity characterization.

So, Dude, it does not matter.

 

[Choupique]

Well, put 15w40 in yours. No money outta my wallet.

How often are you cranking your truck at 40*C? All the time? Probably never. Low idle, cold oil, it matters alot.

 

[ramsare4real]

Well, put 15w40 in yours. No money outta my wallet.

How often are you cranking your truck at 40*C? All the time? Probably never. Low idle, cold oil, it matters alot.

"The difference will be noticeable at the minimum temp each one is suitable for."

 

[vjjack04]

Folks, I just wanted to provide an update regarding this topic. Sure thing, since I have been running the 5W-40 I now have zero noise in the lifter area. This truck is now very quiet with no noticeable issues of any kind. I almost have 30k miles on it. Hope all stays good. And I typically average 18-18.3 mpg in collective road and around town driving (related to my other thread). So, thanks guys for the information.