Oil pressure Inline 6

[JG2020]

Hi everyone,

My oil pressure has never been great but today it dropped to about 5lbs on my mechanical gauges at idle on a hot day.

I just did an oil change last week and used Rotella T4 10-30.

I have a T connector where the stock oil gauge was. One sensor goes to the mechanical gauge and one to the idiot gauge.  I was using 5-30 weight before this.

I took about a 45 minute drive today mix of highway and back roads.

At 65 MPH I was at 1900 RPM and 20 pounds of pressure. The stock gauge read just about the middle.

When I noticed the low pressure on the mechanical gauge the stock gauge was reading low also.

When I start the truck I have about 55 PSI at 1300 rpm.  Runs fine. I hear no noise at all.

Also, on the mechanical gauge the plastic hose was very long and I just coiled it under the dash. Should that be cut and be as straight a run as possible? I have had the truck about a year. This was the first time I saw the pressure drop that low at idle. Usually its at 10 PSI at about 650 rpm

The odometer reads 122K but not sure this is accurate. Prob not.

Any input appreciated.

Thanks!!

[Gary Lewis]

Josh - I don't think that the length of the line nor the turns will have any effect on the reading.  It would if there was flow, but there is no flow, just pressure.

But 5 psi at idle is pretty low.  Is that the first time you've driven it that long in one go?

Also, what oil filter did you put on?  Maybe the filter is plugged?  Or the wrong one?  (Having said that, if the pressure goes back up when the engine is cold then I don't think it is the filter.)

[JG2020]

Thanks Gary, that’s what I thought about the line.  I am using the Fram tough guard oil filter. 

I have taken the same length drive 5 or 6 times. This is the first drive since the oil change though. 

On Thu, May 27, 2021 at 6:37 PM Gary Lewis [via Bullnose Enthusiasts Forum] <[hidden email]> wrote:

Josh - I don't think that the length of the line nor the turns will have any effect on the reading.  It would if there was flow, but there is no flow, just pressure.

But 5 psi at idle is pretty low.  Is that the first time you've driven it that long in one go?

Also, what oil filter did you put on?  Maybe the filter is plugged?  Or the wrong one?  (Having said that, if the pressure goes back up when the engine is cold then I don't think it is the filter.)

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI

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[Gary Lewis]

Fram filters are called "the orange can of death" for a reason.  I use Motorcraft filters.

I'm not saying that is your problem, but it might make a difference.  So I'd change it and see if there's a change.

[JG2020]

Thanks, I’ll give that a try. Should I go back to 5 30 oil ? 

On Thu, May 27, 2021 at 7:21 PM Gary Lewis [via Bullnose Enthusiasts Forum] <[hidden email]> wrote:

Fram filters are called "the orange can of death" for a reason.  I use Motorcraft filters.

I'm not saying that is your problem, but it might make a difference.  So I'd change it and see if there's a change.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI

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[Gary Lewis]

I can't imagine that the oil is the issue.  I'm thinking the filter may have collapsed internally.  But that is just a guess.

[JG2020]

I ordered a few motorcraft filters last night. Is it possible to swap out a filter w/o draining the oil? The filter is pretty high above the pan.

Thanks again!

[Gary Lewis]

Yes, you can change the filter w/o changing the oil.  You'll lose about 1 quart, but it is cheaper than dumping new oil.

[JG2020]

Great . That’s what I thought. I will report back. Is it strange that I get 20psi at 65 mph and 1900 rpm on my mechanical gauge but the stock gauge shows in the middle of normal? 

On Fri, May 28, 2021 at 8:52 AM Gary Lewis [via Bullnose Enthusiasts Forum] <[hidden email]> wrote:

Yes, you can change the filter w/o changing the oil.  You'll lose about 1 quart, but it is cheaper than dumping new oil.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI

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[FuzzFace2]

Gary Lewis wrote

Fram filters are called "the orange can of death" for a reason.  I use Motorcraft filters.

I'm not saying that is your problem, but it might make a difference.  So I'd change it and see if there's a change.

100% change the filter for anything but a "orange can of death"!

When I had the oil changed on my 02 Dodge from a quick change place a short time later I had the same issue, low oil PSI.
When the dealer did the oil change and used a different filter never had that issue.

I go with NAPA gold filters on my pick up.
Pick up a good filter and 1 qt oil. change the filter and add the oil and you should be ok.
Dave ----

[JG2020]

Hi,

I changed the filter and added new oil back to the fill mark.

I get 55psi on startup.  I took a 45 minute drive and I got about 23 PSI at 1800 RPM and 65 MPH
At idle I was between 10-12 PSI. This was on a cooler day about 65 degrees

Helped my son move out his storage unit yesterday. It was about 93 degrees out. 50 minute drive each way.
Startup at 55 PSI again, around 20psi at 45 to 55 MPH
At stop lights I was dropping to 8 PSI and at one point down to 5PSI and low on the stock gauge. A little tap on the gas and it shoots up to 20-24PSI then drops low again.

Shell Rotella T4 Triple Protection Conventional 10W-30 Diesel Engine Oil

Thanks!
Josh

[JG2020]

Any comments on these readings?

Thanks!

[ArdWrknTrk]

It just sounds like you have some bearing wear in your engine.
5w/30 or 10w/30 won't change how thick the oil is at operating temperature.

The W (winter) represents how vicious the oil is when cold, the second number is how thick it acts at operating temperature.
It's been a long time since I followed the SAE ratings but I believe those numbers are for 0 and 100°C, or 32 and 212°F
The W number is only going to effect how quickly the oil flows to the bearings in a cold engine.
The second number is going to effect how easily it passes through and out of the bearings when the engine is warmed up.

Also remember that engines loosen up as the metal heats up and expands.
So you're almost always going to see some drop in oil pressure as the oil thins and the clearances increase.

You could try adding some viscosity index improvement additives like Motor Honey or STP and see if that helps.
Or you could try an oil with a high rating of 40 or even 50 the next time you change your oil.

[Gary Lewis]

I agree with all Jim said.

In addition, I don't think you have anything to worry about.  Yes, the pressure is low when at hot idle.  But assuming the 300 six is like the V8's where the oil pressure pickup point is at the end of the chain, you have enough pressure to the bearings to ensure they are lubricated.  It isn't the pressure that creates the wedge of oil that keeps the crank from the bearings, but the presence of oil.  So if you have 5 psi after all of the bearings and the lifters then you won't have problems.

No, it isn't a new engine with tight tolerances in the bearings that create high pressure in the oiling system.  But it will work just fine.

[Rembrant]

The oil pressure reads fairly low on my 300 inline 6, but I read a comment online the other day that said for the 300, as long as the gauge is showing "any pressure at all", that it is enough...LOL.

[Rembrant]

Here is where mine sits when it is fully up to operating temp. A bit hard to see, but I'd say the needle is on the high side of the "N". When it is cold it reads in the middle, or a hair beyond...but once hot it drops way down to where it is in this picture. Running 15w40 currently. I have no idea what that pressure actually is...but the engine runs really smoothly and quietly. I know in the middle of the factory gauge is around 55psi? I'm maybe at 20psi at my low point? I know my 302 runs around 55psi when hot (according to my dyno day) and it reads in the middle of the factory oil pressure gauge.

[JG2020]

Thanks everyone! Puts my mind at ease a bit. It's nerve wracking when sitting at a light and the pressure gets that low and I am waiting for a loud bang or the like!

So the Motor Honey etc is a safe additive? I always feel cautious of these products. I do use Lucas in the gas. And I added about 5 ounces of Marvel Mystery Oil on the last oil change.

The truck has been running good and I have lot's of elbow grease invested already with more projects in the works.  I still smile every time driving down the road in an old truck!

[ArdWrknTrk]

I've used STP as both a viscosity fortifier and an assembly lube.
It has been around much longer than I have and don't see it demonized, generally.
While I'm not a fan of 'snake oil', you seem to use Lucas products and they're no different.  

I grew up close to MMO, and understand what it is and why I would want to use it (or not)
If anything I'd say putting the detergent and salicylic acid in with your oil change has started to free up a bunch of varnish and that is why your pressure reads lower now.

[JG2020]

Thanks. I am not a fan of additives in general either. My friend was a head mechanic for all ground vehicles at Newark airport and he swore by Lucas. 

But who knows ? The truck was pretty abused so I thought giving it some extra meds for the first couple of thousand miles would be good. 

Prob the best course is to run it the way it was meant to be. 

On Thu, Jun 10, 2021 at 10:14 AM ArdWrknTrk [via Bullnose Enthusiasts Forum] <[hidden email]> wrote:

I've used STP as both a viscosity fortifier and an assembly lube.
It has been around much longer than I have and don't see it demonized, generally.
While I'm not a fan of 'snake oil', you seem to use Lucas products and they're no different.  

I grew up close to MMO, and understand what it is and why I would want to use it (or not)
If anything I'd say putting the detergent and salicylic acid in with your oil change has started to free up a bunch of varnish and that is why your pressure reads lower now.

 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

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