Originally Posted by Tom400CFI

yeah. but they DON'T actually do that...which is why they are snake oil.


O.K. but the problem with THAT, is you can get the same exact results w/any decent, modern oil....especially on a highway driven, 150k motor. 150,000 miles is nothing on a well maintained motor, anymore. Pre-lubers do work, but now days, most cars will fall apart around a well maintained stock motor.

Originally Posted by leesvet

If you do a search on oil pressure you might find a very long, detailed write up done last yr on this subject...

Remember, in ANY hydraulic measurement, especially in oil pressures, that the gauge reading that you SEE is the end of the road for the oil...if you see 30 psi then there was 3 times that
(??? who knows???) at the main bearings where a large % is lost, whats left then goes to cam, lifters then on and up to valve train. AT the top of the engine the OP sender tell you whats left...
Another interesting point is that most filtration systems and filters have a bypass installed that is nothing more than a spring flap that is so soft that you can sneeze and make it open the dump port.

The filter bypass keeps the pressure from building to the point that the filter explodes, so you loose a lot of pressure right there at the very beginning of the system. I cannot say how much but a LOT of oil never makes it past the filter before it gets dumped back to the sump. Many folks suddenly see MORE OP after they install a new oil filter base or a stack-on cooler when they get a fresh bypass spring in there that is a little stiffer and lets more of the oil to go thru the system because its not getting dumped off so soon. Some folks suddenly see LESS pressure because they installed a softer bypass...nothing wrong with the engine but you'd think there was seeing the residual OP on the gauge.

Now, thicker oil is NOT necessarily better for a loose engine BECAUSE it MAY stay in the loose mains and hold more oil between the bearing and the crank surface, BUT it is also much harder to push thru the many more small orifices that it must go thru. Again, you will see whats left and with a heavy oil that may/may not be accurate since that's residual oil pressure after its done its job and it takes so much more to move the thicker oil.
My current engine with somewhere between 150 and 200,000 miles, and it idles
HOT (225* @ 600 rpm) @ 20-25psi. If I get stuck in 100+ ambients in traffic and my engine temps go to 230+ it MAY drop below 20 at 600 rpm. The instant the rpm goes up so does the pressure until freeway cruising speed at 17-1900 rpm gives me 40+ psi and more as rpm rises. IIRC 70-80 mph can get me 45-50 psi @ 200 degrees eng temp. That ain;t bad for an eng with this kind of milege.Usually it runs 20ish hot idle and 35+ anywhere above idle and this is a HI-MILES engine...it has been very well taken care of and I am run 20/50 syn summer and 5-30 syn winter and its always been dosed with
Pro-Long. An interesting note, the 5/30 will generate as much pressure or more in some situations than the heavier wt oil does...because it flows easier thru the system. Thick oil is harder to move.
I credit the "snake oil" ProLong,
(that's what science is called when folks do not understand it) with the high milege and the fact that it only uses maybe a 1/2 qt in 5000 miles.... Most of the small amount of oil that is used goes out thru the valve seals @ cold start or the wet spot on the drain plug....

Point is, if the engine is brand new and tight you will see LESS difference between hot/cold temp cycles. Once the eng is broken in and loosened up it WILL loose more oil thru the bearings thru slippage and the remainder of the oil that's still under pressure then makes it to the gauge, AFTER its gone all thru the engine.

Nothing will fix pressure loss thru worn bearings or loose valve guides/seals. Forcing more oil thru those worn areas does nothing more than provide more oil in vol that gets to the top end. It does not solve the problem or worn internal parts. That may provide a false sense of security for a while but as wear continues...the pressure will begin to fall again. If your oil TEMP rises sharply during brief hi-rpm runs, that's a sign that there is a LOT of slippage thru the bearings. Oil temp should be similar to water temp with some variation due to rpm.

As others have stated, 10 psi to 1000 rpm is what you NEED. If you have more than that then you have more than enough and if it is a great deal more, then you have plenty.

Bottom line, clean oil at lower pressure is better for an engine than high pressure oil that's lost its viscosity and carries a ton of dirt. Pressure isn't everything. Many engines are designed to run on low pressure/hi vol. I had a Bike hi-performance engine that was designed for 4 psi OP with a redline of 10500 rpm...That sounds plain scary, but it worked.

Originally Posted by leesvet

Mr Tom, you are absolutely entitled to your belief (disbeliefs?) and I respect that !

However, the 150K on the motor that I am referring to was in no way "babied" on the hiway, or driven easily. It was for the most part abused and used and run to its design limits or beyond almost daily. In fact, the reason that I was looking at the inerds was because I spun it a bit too far and it shattered a piston due to some self induced knock...nobodies fault but mine.

That's what started the Q&A discussions from the machine shop that did the teardown and machine work that was also a speed shop. They wanted to know what happened to destroy a "new" engine like that. They all but called me a liar when I told them of the miles....
I did change the oil between 2-3000 miles and used a syn blend for a while then went to full syn and sometimes stretched the oil change to near 5000....Like I said, it was not babied...

Being in engineering and hydraulics I understand a lot of the science behind some of these products. Boundry layer and surface tension of lubricants come into play with these additives. But, there is a down side as well. I have not had any issues because I do a "decontamination" of my engine annually to rid it of build-up and sludge inside as well as excess zinc and PTFE that might have accumulated from my chemical dosing of the oil. By adding a qt of marvel oil and running a few hot/cold cycles, I can drain out most of whatever does not belong. That may be of some help with the longevity, not sure but I do it anyway. This last decon I did last month yielded an increase in oil pressure when hot, and a quieter valve train that WAS ticking a little. Now its church quiet. After dumping the old oil out with the contaminates I add my new oil , the Prolong and continue my reign of terror on the streets. This engine is approaching 200K with no issues so far. Its getting loose of course but its not burning, not misfiring and its in no way a slug...
My conclusion is that something that I do is helping...prolong? maybe. My flush/fill procedure? maybe. A combo of both? probably so. Whatever it is, its working and I'm staying with the program.

Many of these products do exactly what they say they will do, until they are strained out of the fluids by the filter. Others have some undesirable side effects...seals and even corrosion on certain metals. I could not find derogatory info on Prolong and I did read statements from a bunch of believers, so I tried it. Until I blew that motor I had NO WAY of knowing if I was tossing $20 out the window each maint cycle...but once I DID see the result of the snake oil...Since then I do not drain the oil until I have the Prolong booster dose in hand with the new filter and oil.

Works for me And when I build the next engine, I will probably treat it the same way since I am getting great results out of the current system I'm using.