What is your oil pressure?

[User_3336]

43,000 miles.
I use Shell Rotella 5W-30 oil. Oil pressure cold indicates above 50PSI idling.
After the engine, coolant and oil are to operating temperature, oil pressure indicates above 35PSI idling.
Occasionally, I will use 5W-40. Same pressure readings.

Curious, why are you using 5w-30 and 5w-40 in an engine where the manufacturers states 5w-20?

 

[My1stHemi]

Curious, why are you using 5w-30 and 5w-40 in an engine where the manufacturers states 5w-20?

 

[stevj]

Curious, why are you using 5w-30 and 5w-40 in an engine where the manufacturers states 5w-20?

March 2019, going up a 7-mile-long 6% upgrade on I-5 in the Siskiyou mountains in southern Oregon.


How good is that 5W-20 in this situation? I don't know, but I drive this highway often.
That 20 in 5W-20 is only correct at 212 degrees F. How much thinner is that oil at 237 degrees F?
I will continue to use 5W-30 and 5W-40 (summer) synthetic to protect that excellent 5.7L engine.
This is my preference.

Steve

 

[Dusty1948]

At 11 degrees F ambient this morning within seven seconds I was reading 64 psi oil pressure on high idle. At road speed of 25-50 MPH it was still reading 60 psi. By the end of my 16 mile drive the coolant temperature was at 197F, oil temp at 202, road speed oil pressure was at 55 psi, and oil pressure at 36 psi at idle.

Currently using Pennzoil Ultra Premium 5W-20.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 045618 miles.

 

[My1stHemi]

Oil change Saturday. Fresh 5w-20 shell rotella gas truck oil.

 

[sppb32]

I rather have high oil flow than high oil pressure, if the oil gets hot that means the bearings are getting hot and you need high flow to cool them down, you use a higher oil viscosity than the manufacturer recommends and the temperature is going to be even higher is not doing you any good, this new engines are not like the old small blocks Chevy, they have very tight clearances running high viscosity oil is asking for trouble.
My other car is a Hyundai Genesis coupe 2.0T highly modified, some of the guys in the forums started using oil for diesel engine 10W40 they said it was better for the turbocharged engines manufactures suggests 5W30... well... all you see is spun bearings everywhere, high oil pressure = low oil flow = high oil temperature = metal expands = seized bearings
Oil is not just to lubricate cooling the bearings is just as important.

 

[cesfra55]

Your pressure sounds fine to me; here's the 5.7 spec. I get into the 30's psi too in my Durango when fully warmed.

View attachment 17476



The Pennzoil Synthetics, both Platinum and Ultra Platinum, are some of the best engine oils currently on the market. See BITOG.

I concur with Electrical. My oil pressure fluctuates between 30-32 at idle when oil fully warmed up in my 2020 RAM 1500 HEMI

 

[cesfra55]

Driving when warmed up 51-53
Idling at light(warm) 33psi.

Agree with you, my oil pressure fluctuates between 30-32 at idle when oil fully warmed up in my 2020 RAM 1500 HEMI

 

[GKIII]

March 2019, going up a 7-mile-long 6% upgrade on I-5 in the Siskiyou mountains in southern Oregon.

View attachment 80970
How good is that 5W-20 in this situation? I don't know, but I drive this highway often.
That 20 in 5W-20 is only correct at 212 degrees F. How much thinner is that oil at 237 degrees F?
I will continue to use 5W-30 and 5W-40 (summer) synthetic to protect that excellent 5.7L engine.
This is my preference.

Steve

That thicker oil also means more resistance, which means more heat generated from friction since that motor's tolerances were not stacked with 30 weight oil in mind at operating temp. Combine that with the fact that thicker oils generally don't transfer heat as well your 'solution' is basically creating a self fulfilling prophecy of hot oil.

The fact of the matter is that your truck was designed to use 5w-20 oil that meets the requirements of MS 6395, which among other things requires that approved 5W-20 oils have a minimum 2.6 centipoise High Temperature High Shear (HTHS) viscosity at 150C (302F). Notice that is far above your truck's measured oil temp of 237F. So long as you use a high quality synthetic 5W-20 that meets that rather pedestrian requirement your truck will be more than fine.

If you are concerned about high oil temps while towing, you're probably better off installing an auxiliary oil cooler than changing the weight of your oil (but then you run into the problem of possibly cooling it too much ).

Edit: Changed 0W to 5W, I wrote this last night and am used to using 0W-20 in my other vehicles hah.

 

[Oldphart]

That thicker oil also means more resistance, which means more heat generated from friction since that motor's tolerances were not stacked with 30 weight oil in mind at operating temp. Combine that with the fact that thicker oils generally don't transfer heat as well your 'solution' is basically creating a self fulfilling prophecy of hot oil.

The fact of the matter is that your truck was designed to use 0w-20 oil that meets the requirements of MS 6395, which among other things requires that approved 0W-20 oils have a minimum 2.6 centipoise High Temperature High Shear (HTHS) viscosity at 150C (302F). Notice that is far above your truck's measured oil temp of 237F. So long as you use a high quality synthetic 0W-20 that meets that rather pedestrian requirement your truck will be more than fine.

If you are concerned about high oil temps while towing, you're probably better off installing an auxiliary oil cooler than changing the weight of your oil (but then you run into the problem of possibly cooling it too much ).

I'm not a chemist but it is my understanding that the 5 in 5w-20 is the minimum viscosity the oil can have. If one runs a 5w-20,30,40, etc. those oils would all start at 5w. Now, I'm not sure exactly how this happens, but it is again my understanding that the multi-viscosity oils will maintain the 5w as they heat up, and the upper number is only an indication of how much heat they can absorb before they fall below the 5w rating. In other words, they do not actually thicken as they heat up, just maintain the lower viscosity rating. Assuming the last sentence is true, switching to a 10w/30 would mean that oil never falls below the 10w rating; that could be the issue with the newer motors.

The above is all "Old School". I'm sure things have changed over the years and I'm not into car maintenance as much as I was in the past. I remember back in the day, I used Castrol 20-50 bean oil in everything; cars, motorcycles, lawn mowers and never had an issue as long as I changed it regularly.

 

[GKIII]

I'm not a chemist but it is my understanding that the 5 in 5w-20 is the minimum viscosity the oil can have. If one runs a 5w-20,30,40, etc. those oils would all start at 5w. Now, I'm not sure exactly how this happens, but it is again my understanding that the multi-viscosity oils will maintain the 5w as they heat up, and the upper number is only an indication of how much heat they can absorb before they fall below the 5w rating. In other words, they do not actually thicken as they heat up, just maintain the lower viscosity rating. Assuming the last sentence is true, switching to a 10w/30 would mean that oil never falls below the 10w rating; that could be the issue with the newer motors.

The above is all "Old School". I'm sure things have changed over the years and I'm not into car maintenance as much as I was in the past. I remember back in the day, I used Castrol 20-50 bean oil in everything; cars, motorcycles, lawn mowers and never had an issue as long as I changed it regularly.

The "5w" in 5w-20 means it has the viscosity of an SAE 5W oil when cold, and the 20 means at 100C (212F) the oil behaves as if it were SAE 20W. Multi-grade oils were developed so the viscosity change between cold and hot temperatures were not so extreme.

With that said, oils obviously experience temperatures beyond 212F so manufacturers often specify specific behaviors in those conditions, one of those is the HTHS requirement I referenced above. The 5W-20 oils that meet the MS6395 spec (the Chrysler....err FCA...er Stellantis oil specification) are verified to have acceptable viscosities at temperature far above 212F.

There is no reason to use a heavier oil in these engines, especially one that's low mileage. Despite the fact it's an iron block pushrod, the tolerances of this engine are not 'old school'. All you're doing is making everything hotter by going heavier (therefore introducing premature wear). Now, if you're running at 250k miles and you're trying to squeeze a little more out of a well-worn motor that's running like crap, go for it. By that point the tolerances have grown quite a bit and if you can get an extra 6-12 months out of it by going a little heavier to fill in those gaps, great.

 

[Oldphart]

Thanks GK...appreciate the explanation.

 

[GKIII]

Thanks GK...appreciate the explanation.

I just noticed you're from Orange, small world. I grew up there...went to LCM.

 

[HoosierTrooper]

Let’s clarify a few things. The first number is the winter rating, which is what the “W” stands for, and an oils winter rating is determined by how it performs in two tests. The first is the cold cranking simulator (CCS), which measures the ability of the oil to allow the engine to crank at cold temperature, and the second is the mini-rotary viscometer (MRV), which measures the oils ability to be pumped at cold temperature. In the CCS test a 0W oil cannot exceed a viscosity of 6200 cP at -35C and the 5W cannot exceed 6600 cP at -30C, while the 0W cannot exceed 60,000cP at -40C and the 5W cannot exceed 60,000cP at -35C in the MRV test.

The second number is the oils kinematic viscosity at 100C (212F), which is considered the normal operating temperature of an engine. Each grade is actually a range of viscosities, not a single number. For example a 20 grade oil can be anywhere between a minimum viscosity of 6.9 cSt and a maximum of 9.29 cSt with a minimum HTHS of 2.6 cP, while the 30 grade range is from 9.3 cSt to 12.49 cSt with a minimum HTHS of 2.9 cP. The difference between the minimum HTHS of 20 and 30 grade oils is only .3 cP, and there’s no denying that a slightly higher HTHS is going to provide more protection, which may be important in high engine stress situations.

You used the terms “tolerances” and “tolerance” when you’re actually referring to an engines clearances. Clearance is the distance between the moving parts and tolerance is the amount of allowed variance in the clearance dimensions Engine clearances haven’t changed much in the last several decades but tolerances have improved with modern production methods. The idea that the clearances in the 5.7L engine are too "tight" for the slightly thicker 30 grade is simply not accurate. During a cold start 5W-20 is going to be many times thicker than a 5W-30 is at operating temperature, and will remain so until it’s fully warmed up. Also, the difference in KV in most API rated oils is fairly small between 20 and 30 grades. For example, the KV of Pennzoil Platinum 5W-20 is 8.6 cSt while the 5W-30 is 9.8 cSt. At 40C (104F) the KV of the 5W-20 is approximately 46 cSt, which is 4.5 times thicker than the 5W-30 is at 212F. If a fully warmed up 5W-30 is too thick to fit through the “tight” clearances of the engine then how can a much thicker cold 5W-20 do it?

https://www.shell-livedocs.com/data/published/en-US/c3f144cb-960f-45fc-9e05-ede27ed32625.pdf

https://www.shell-livedocs.com/data/published/en-US/37525be3-79fd-4091-a7e9-92724460013a.pdf

The 5.7L will function perfectly using a 30 grade oil that’s only a couple cSt thicker than the recommended 20 grade, it's up to each owner to make an informed decision whether or not he or she wants to go outside the recommended, not required, 5W-20 in their 5.7.

Here is SAE J300 which shows all of the grades viscosity information.

 

[cesfra55]

When engine oil is cold oil pressure is over 50psi
When oil is hot 220 degrees pressure drops to 48psi while cruising and 28psi at idle.

That seems to be a correct statement at low idle and hot oil. However, oil filters do make a +/3 3 PSI difference. While a K&N gave me a 30 PSI reading at low idle, a MOPAR filter gave me a 27-28 PSI reading at low idle.

 

[cesfra55]

When engine oil is cold oil pressure is over 50psi
When oil is hot 220 degrees pressure drops to 48psi while cruising and 28psi at idle.

That seems to be a correct statement at low idle and hot oil. However, oil filters do make a +/3 3 PSI difference. While a K&N gave me a 30 PSI reading at low idle, a MOPAR filter gave me a 27-28 PSI reading at low idle.

 

[cesfra55]

Btw, beware of K&N air & oil filters. Their designs focus more on flow than filtering out as much as possible.

That's correct! I swapped my K&N to a MOPAR to assess the oil pressure differential and the DP was about +/- 3 PSI. The K&N is way less restrictive than the Mopar and flows way better. However, I wouldn't risk OEM filtration capability for higher flow rates and worst particle count. I would rather sacrifice a bit PSI's of pressure for better filtration

 

[Mountain Whiskey]

I believe you guys think an internal combustion engine is a little more high tech than it really is.

 

[BowDown]

My suspicion is that the 5w-20 is specified because of the lifter requirements. The lifters have a bleed down hole and an orifice in the disk under the pushrod. too high of weight, the 20 number ands the lifters may not work properly. I wonder how many of those HEMI lifter failures are due to the wrong oil being used.

My Z06 has Lunati race lifters that have similar tolerances to the HEMI lifter, they also have a oil weight warning

DO NOT USE OIL HEAVIER THAN 5W40

5w20 will take heat just fine and nothing you're doing in this truck will tax that weight of oil

 

[SD Rebel]

My suspicion is that the 5w-20 is specified because of the lifter requirements. The lifters have a bleed down hole and an orifice in the disk under the pushrod. too high of weight, the 20 number ands the lifters may not work properly. I wonder how many of those HEMI lifter failures are do to the wrong oil being used.

My Z06 has Lunati race lifters that have similar tolerances to the HEMI lifter, they also have a oil weight warning


5w20 will take heat just fine and nothing you're doing in this truck will tax that weight of oil

I think you are right. There was a video I saw from a FCA/Mopar technician who specializes in Hemi engines, he specifically mentioned than 5W-20 was required to get the best lubrication from the tight tolerances of these modern engines. That 5W-20 does help with mpg, but it's also so it can lubricate the upper valvetrain assembly better.

He mentioned that most of the issues he saw with higher mileage motors were due to the wrong viscosity and lack of lubrication. I think there are too many people who are using old world thinking in regards to modern lubrication, that it's not about the thickness = durability, but the ability to reach higher and tighter areas to lubricate properly, and that a thinner oil is actually better for that.

I don't honestly know, but when you have companies back-specing engines that originally had thicker oil, it's not about the CAFE numbers since mpg doesn't apply to used vehicles for manufacturers. Example is Ford changed their recommendation for modular V8s in mid-2000s from 5W-30 to 5W-20, they back-speced all the way to 1997 model year. They said the engines would last longer on 5W-20.