Oil Pressure

Grumpy Bear · April 17, 2019

12 hours ago, dukedkt442 said:

Thicker oil + small passages = fluid restriction. That’s unarguable.

Actually this is true. Both statements. The question becomes a matter of degree that it is true.

The difference between 0W20 and 5W30 at 150 F and above is about the same difference in viscosity at water and milk at room temperature or roughly 2 cSt. Measurable? Yes. Does it matter? Hardly. It's the reason there is no measurable difference in hot oil pressure trading between the two SAE grades. Neither your VVT nor your DOD will notice the change FUNCTIONALLY.

That said it doesn't mean you wont 'sense' a change. Ever notice on a really hot and still day that your motor gets all whisper quite? You notice it more on a tractor on an air cooled bike.

Seems both of you are right and if you shift your focus to 'degree' of difference you might even agree...maybe.

Edited April 17, 2019 by Grumpy Bear
Improper tense correction.

16LT4 · April 17, 2019

9 hours ago, SierraHD17 said:

And your 2019 hemi is still the same engine as the 09 lol. Not to mention a 2019 car still specs the higher viscosity oil with the same engine setup the truck runs... but what the hell does Chrysler know... little passages right... yeesh.. But hey... who is counting. It makes no difference and no you can't prove otherwise. But believe whatever tickles your fancy. Its the same reason GM specs 5w30 or higher in the LT1 and 0w20 in the truck L86. And before you say a word about it.. they are part number for part number the identical long block. But those little passages you know.... hahaha.

True, 2009 was the first year of the G2 engine. However, 5w-20 was and still advised for the 5.7 no matter whether car or truck. Even some Chrysler TSBs out on the issue... but you’re right, what be heck does Chrysler know? No, I don’t have a 2019 Chrysler product of any sort, never said I did. (Jeesh I cant believe we’re discussing Dodges so heavily). What I did say is that it is worth taking lessons learned elsewhere and applying what can be applied. You scoff and oil passage size... like someone who has never torn one apart to see them. A 5w-20 will have less of a viscosity range than the 5w-30, so pressure and flow characteristics deviate less from the mean. Enough to cause issue? AFM is such a contentious item, coupled with VVT (also driven by pressure), do you want to give it more reason to “be unhappy?” Be the guinea pig. But hey, what do the GM engineers know? Clearly not as much as armchair quarterbacks on a forum.

SierraHD17 · April 17, 2019

4 hours ago, dukedkt442 said:

True, 2009 was the first year of the G2 engine. However, 5w-20 was and still advised for the 5.7 no matter whether car or truck. Even some Chrysler TSBs out on the issue... but you’re right, what be heck does Chrysler know? No, I don’t have a 2019 Chrysler product of any sort, never said I did. (Jeesh I cant believe we’re discussing Dodges so heavily). What I did say is that it is worth taking lessons learned elsewhere and applying what can be applied. You scoff and oil passage size... like someone who has never torn one apart to see them. A 5w-20 will have less of a viscosity range than the 5w-30, so pressure and flow characteristics deviate less from the mean. Enough to cause issue? AFM is such a contentious item, coupled with VVT (also driven by pressure), do you want to give it more reason to “be unhappy?” Be the guinea pig. But hey, what do the GM engineers know? Clearly not as much as armchair quarterbacks on a forum.

Chrysler runs afm as well as VVT on the 6.4... it's a 5w40 spec based on application. Just like the 5w20 is adequate for protection and gives them the fuel economy numbers you want. That's it... that's all it is regardless of who is manufacturer. Oil viscosity matters a lot less than most believe... because most have no idea what viscosity means in the first place.

Yes I scoff at passage size... you should look how small it is on the lifters, the solenoids, the cam phaser... and then really start to wonder when those same parts work fine with different specs in the past as well as applications beyond brand new trucks lol.

Engineers work within constraints of what parameters they are given. Fuel economy, emissions targets, ride and harshness, noise, etc. Just because something comes specified to give those numbers they wanted during testing doesn't mean it's the best for the life of the component... especially when you conveniently drop 40000 miles from your powertrain warranty. Or even more when you specify otherwise with the same components in differing applications. But believe what you want... your probably will never have an issue running what the book tells you too and for most it's the best practice. Just like I don't have many issues pushing things well beyond their design spec outside of the realms of discussion on this forum. Is what it is.

Edited April 17, 2019 by SierraHD17

L86 All Terrain · April 17, 2019

5w30 in an LT engine? It wont hurt it I suppose, may be even better for it. You have to look at the film and shear strength of the oils to really see if there would be a huge difference in wear. The 0w-20 is partly utilized to get every last ounce of economy out of these trucks to meet CAFE. If we didn't have all these hippies around, GM would probably still use 5w-30. I usually go 0w20 in winter, and 5w20 in summer. On the LS motors I used 5w30 winter and 10w30 summer.

SierraHD17 · April 17, 2019

1 hour ago, L86 All Terrain said:

5w30 in an LT engine? It wont hurt it I suppose, may be even better for it. You have to look at the film and shear strength of the oils to really see if there would be a huge difference in wear. The 0w-20 is partly utilized to get every last ounce of economy out of these trucks to meet CAFE. If we didn't have all these hippies around, GM would probably still use 5w-30. I usually go 0w20 in winter, and 5w20 in summer. On the LS motors I used 5w30 winter and 10w30 summer.

They still spec 5w30 for normal usage or higher for track use on Camaro and Corvette LT1's. Same long block as the 6.2 truck so.... lol. It's pretty easy to figure out it's for economy and nothing more.

Edited April 17, 2019 by SierraHD17

Jacoby · April 17, 2019

My 2012 CTS V with LSA specs 5w-30 as do the new ones with LT's. Truck specs OW-20. I believe it to is for fuel efficiency. As said earlier my hot idle pressures are around 38psi and on the gas upper 40's. With that kind of psi I don't see a need to change from whats spec'd so i'll probably keep running 0W-20. If I had low psi like Ive seen in here I would consider going up in weight