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oil pressure drops to 22 lbs @ 210 degrees, and 5 lbs @ an idle, when towing my 5th wheel 12,500 lbs weight
What year truck and what weight of oil? FWIW, out of the 3 weights of oil I've run over the years (15/40, 5/40 & 10/30), the 5W40 always had the lowest oil pressure (<30 psi) when hot. The problem with pressure below 30 psi is the piston cooling oil "squirters" which cool the bottom of the piston operate at 29 psi.
My weight of choice for the last 8+ years is 10w30 year round. My TT is a 38' Outback that weighs 10,500 lbs...

My .02¢
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I run 5w40 full syn 9000, specifically because it holds psi at higher temps (280+) and doesn't thin out. Never drops below 45 @1800r.

Is this a new problem while running the same type of oil?
What did it do in the past?
Or did you just notice the psi at higher ECTs?
 
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I run 5w40 full syn 9000, specifically because it holds psi at higher temps (280+) and doesn't thin out. Never drops below 45 @1800r.

Is this a new problem while running the same type of oil?
What did it do in the past?
Or did you just notice the psi at higher ECTs?
HH,

It was during the heady days of pushing Dmax limits, 2008-2010. The 5W40 problem was in 2004.5-2007, trucks that were pushing 500+ HP and cracking pistons. The majority were running 5W40 because it was the only synthetic oil available at that time and the owners thought that syn would protect better.
A local Idahoan, Josh H., cracked a piston in his '06 while running 5w40 and he noticed right before it popped, oil pressure of 20 psi all while pushing 500+ HP.
As I stated, in my experience, the 5w40 had lower oil pressure when hot but "flow" when cold is a benefit in cold weather.
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Discussion Starter · #7 ·
I thought synthetic would lower the oil pressure excuse my ignorance I don't understand this diesel stuff pressure excuse my ignorance I don't get this diesel stuff excuse my interest
 

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...the 5w40 had lower oil pressure when hot but "flow" when cold is a benefit in cold weather.
Wasn't that running non coolant cooled turbo(s)?
IIRC, the culprit was excessive oil temps (unknown) vs ECT seen?

Added temp sensor revealed the temps spiking beyond 280 toward 300 as the psi plummeted. In one case, a supplier offered 'em (free) the 9000 to test.
Duplicated the same conditions, same heat spikes, never dropped below 45.

But their formulation differs from other syns.

I sometimes push the extreme (weight+heat+steep), but couldn't justify $1k for an aux oil cooler. So I made the switch for protection and it always holds psi. Pricey, but my UOA is free.

I'm not saying the OP should switch to one or the other.

Oil pumps on these rarely fail....I can't even recall a mention of having to replace one.
Wondering if it's a gauge or sensor issue.
Do you have another way to monitor psi than the stock gauge?
 

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Discussion Starter · #9 ·
Had a replacement manual gauge put in connected to the electric sensor opening in the block it showed 25 lb versus the 30 lb that the electric sensor was showing the check that worked on it was afraid to remove the plug in the filter housing because it was corroded and he was afraid it was going to break
 

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Discussion Starter · #10 ·
As the heat range goes from approximately 180 degrees to 210 degrees is when the PSI drops dramatically seems to be heat-related
 

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Maybe it is the pump then.
Not an easy thing to access.
 

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Hook,

All 2004.5 & up turbos are coolant system cooled turbos. Not sure if LB7's were non-coolant though...

Rob
 

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There is a common misconception that 5W-40 is "thinner" at operating temps than 15W-40. That is a fallacy. In fact they are theoretically the same (40W) at operating temps. And they are, again theoretically, the same as straight 40W would be at those temps.

The only difference is actually when the engine is cold. At that point the 5W is thinner than the 15W, so is the 10-30 actually. The 10-30 is also thinner than either the 5w-40 or the 15W-40 at operating temps.

The benefit of the 5W, in my mind, is better lubrication flow when the engine is cold, even in the hot summer Southern months. Even though Shell now makes their Rotella T6 in both weights now I still prefer the 5W-40 year round for the reasons above.

I am betting that you are relying on the factory OPG, which is notoriously inaccurate. You should get an Edge Insight or similar monitor to get the true pressure.
 

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Hook,

All 2004.5 & up turbos are coolant system cooled turbos. Not sure if LB7's were non-coolant though...

Rob
I was referring to big power, as in a compounds.

get the true pressure.
OP stated test gauge on sensor.
 
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