Because it doesn't matter to engine longevity if some is left behind.

No engine, gas or diesel, completely drains all the oil oil. Some will always be left behind. It's a small enough percentage of old oil that it doesn't actually affect the longevity of the engine, or degrade the new oil.

Based on that, some people see it as a waste of time, as it's not typically a quick process to suck out the oil from the HPOP. Others see it as piece of mind.

It doesn't hurt anything, but in the end it's not really helping either. If it's worth it to you to change it, then continue doing so if you wish. No harm is being done as long as you're careful not to get any dirt or debris in the reservoir, or poke something through and break the screen at the bottom.

 

Yes, the HPOP draws oil from the bottom driver's side of the reservoir.

The LPOP continuously supplies the reservoir with oil. Any excess oil drains down the engine front cover through an overflow. The rest is pulled from the bottom of the reservoir to the HPOP (there's a screen down at the bottom), where it is pumped through and sent to either the injectors or past the IPR and dumped back to the motor. The more oil that is diverted to the injectors, the greater the pressure at the head (picked up by the ICP sensor).

 

Yes do the math.

7.3 oil capacity total 18 qt
Oil pan/filter 15 qt
Hpop res. 1 qt
Heads/top end 2 qt

If you leave 3 qts of dirty oil in the engine you are diluting the clean oil by 16.67%

If you were to suck 1 additional qt out of the Hpop res then you would reduce the dilution of clean oil to 11.1%

5% performance gains are typically hard to come by and I am sure if it was a 5% gain in Torque everybody would be doing it, but 5% reduction of dirty oil in your fresh oil ? Meh,

 

The picture does not show where the oil goes after the reservoir, I assume it goes through the injectors? Now where on the reservoir is the oil sucked from? If the oil is sucked out of the middle of the reservoir(top to bottom) then its possible that the oil does not all circulate. The old gunked up oil could be sitting on the bottom of the reservoir never moving if its just sucking the new oil out of the reservoir. It seems like this could be possible because people SWEAR that the oil is seperated every second but if you have ever emptied the oil from the reservoir you know how black that stuff is! Even 100 miles after a fresh oil change.

 

Nothing to see here . Move along

 

It sounds good on paper, but doesn't necessarily transfer over to reality. Why don't you get a #4 ORB fiting with a hose barb on the end of it. Put a rubber hose on the barb and route it to an empty jar. Then remove the plug on the top of your HPOP reservoir, screw your hosed fitting in, and crank the engine to see how much oil moves through the reservoir at 100 - 200 rpm's.

Crank the starter for 30 seconds and measure the volume of oil. Then multiply that by 10 or 20 to account for driving rpm's and multiply by two to get volume of oil in one minute.

If there's some untouched oil hidden in some corner of the reservoir that doesn't get flushed out in that volume, then you might as well leave it there an never worry about it.

If you're just trying to be **** and change as much oil as possible when you change your oil, why aren't you (or Powerstroke help Bill) pulling the plugs on the oil rails and draining those too?

 

Yes !!! pull the galley plugs in the heads , Pull the block plugs , remove the valve covers and suck all that nasty standing oil out of all the hidden spots . Heck .. the pan needs to be removed also ! It holds a quart or so even when drained ! My gosh ... We need to totally rethink an oil change !

 

Post #32 answers this.

The same thing comes up over and over again on this forum.

This is what a drained HPOP reservoir looks like after I believe 140K miles if I remember correctly:



Not once was the oil removed out of the HPOP during an oil change. And no it was not cleaned prior to snapping the picture, just left upside down to drain overnight.

If you have any sludge build up in your HPOP reservoir, it's because you have engine problems or extremely poor maintenance. Normal oil changes will not cause sludge build up in the reservoir. The oil simply moves too fast. If there is sludge, the reservoir is the least of your concerns.

Here's some information on how the HPOP works: A stock 17 degree HPOP is a fixed (not variable) displacement pump. It always moves 7.2cc's of oil per revolution (for a normal, healthy HPOP), and it spins at 85% of engine speed. So let's say your truck is idling at the typical 680 RPM's. That means the HPOP is spinning at 578 RPM's. That's 4161cc's of oil pumped every minute the truck is at idle. 4161cc's equates to just slightly over 1 gallon. One gallon of oil pumped through the HPOP system per minute..... at idle. That's a lot of oil.

Just think about the math at higher RPM's.

That's why the oil in the HPOP system cannot be different than the oil in the crankcase. It simply moves too fast, and there's such a high volume of oil flow. So no matter what you think you see, the oil in the reservoir is the same as what is in the pan.

That volume of oil flow (and subsequent pressure) is also why 1) maintenance is important, and 2) it's best not to use additives in oil.

 

Thanks Curtis. That's what I had meant by do the math. I was just too lazy to look it all up.

And who decided to let you be a moderator?

Does that mean you're going to disappear like the rest of them have?

 

@F350-6, nice epigram, very clever.....Oil Faithful!

 

 

Cash talks!

J/K of course.

I know Jim has a ton on his plate and recently switched jobs so he wouldn't have to work 70+ hours a week.

Scott is still here, albeit not nearly as much as he would like.

I'm here everyday, I just don't post as much as I used to because of all the stuff I have to cover. In fact, that's why Curtis was brought on board, to help mod the '04 - '08 F150 forum.

Stewart

 

Oh I'm sure FTE will regret this decision

 

^^^ Agreed a good vacuum jar is a nice thing to have.

I literally spit on coffee... that is great.

 

This is literally the purpose of what Bill is seeking to do. The flow diagram clearly demonstrates that the reservoir oil only goes from there into the hpop and then to the "dead head" end of the system. The galley is where the old oil is located. Which is what Bill clearly states in his video.