So, Idemitsu Rotary Engine Oil 20W-50 is a good choice for the new engine, right?

That works. A little expensive I imagine but I don't know all it's specifics compared to the competition.

Paul.

Well, you know me... :D:

Hey OD, are you still running the diesel oil?

Responding mostly to hiflite's previous post - not quoting since it's GINORMOUSSS!

To my understanding, the difference in viscosity of 20 weight vs 40 weight at normal operating temperature (180-220) is pretty close, so I would imagine the loss of flow would be relatively minimal. And 0W doesn't always mean it has lower viscosity - it sometimes has the same, just better flow rate at lower temperatures (I think below 32F).

I'll look into the Mazmart oil pump in the future though, better safe than sorry!

Yep i am still trucking! Just sent my 2nd uoa in.

Hiflite--man you are thinking to much!! Making me dizzy and my head hurts.
You see the way i understand it is that our oil pump is a constant volume pump. No matter what the viscosity of the oil. it is going to pump the same volume of oil. Also that is the reason pressure goes up with heavier viscosity! You are pumping the same amount (flow) of a heavier oil --so more resistance --so more pressure required to flow the same volumne.
Even with the oem bypass the max oil psi occurs much higher than 4-5K so using Paul's Pump it Up mod will not reduce oil flow at all. The pump actually seems to have the capacity to continue to increase the pressure a little even when the by pass is open some. Remember it is not an open/closed bypass--its gradual.
I need my meds now.
OD

I've been wondering if, at rebuild time, it might be possible to use the S2 rotor housings and plumb the S1 MOP into these connections for S1 owners (rather than replace the PCM and all the other S2-specific plumbing); but I've been concerned that this might, assuming its even possible, result in inadequate flow for all three nozzles.

Would the increased pressure result in better dynamic balance at high RPM?

Denny, do you think that the increased pressure might be force-feeding your MOP? Alternately, since you're using a high viscosity oil, before the OP mod, could your MOP been starved for feed oil?

I dont have any way of proving that the rotors are better balanced with a higher oil pressure---wish I did! Silkilicious does continue. I hate when I say such subjective things. It is I was just impressed and too me it was really apparate---but hey I am weird anyway.
Thats the thing about the omp. It is also a fixed volume pump. maybe it wasnt getting enough oil to itbefore? But wouldnt that cause air bubbles in the lines? I dont have a clue and it doesnt make sense. Maybe I am imagining this--but it sure seems like it. I am having to add more oil now a days.
OD

i don't think the heavier oil is the only factor or biggest factor in this case.
I got my car on Oct 31, probably with 5W20. I changed it to 5W30 and then to 10W30 and consistently use very little oil.

Yes OD, I don't have concrete evidence, but I am almost certain this was an issue for owners not keeping their engine oil pan full, oil starvation at the MOP is/was an issue for the MOP and Engine supply also.;)

Because it's a constant displacement pump, the viscosity has no effect on volume through the important part of the oil system, until the bypass opens. After that, while the volume per pump revolution remains constant, part of that volume goes straight back through the bypass to the oil pan, without going through the bearings, etc. As you increase rpm, past the ~80 psi bypass setting on the stock system, the oil flow going through the engine no longer increases with rpm. My measurements on the stock system shows that the oil pressure rises until 4-5k rpm where it reaches ~80 and stays flat from there. The transition from the "increasing flow increasing oil pressure" mode (good) to the "constant flow constant oil pressure" mode (bad) occurs when the bypass valve opens to keep the op from rising further. With a fully warmed engine, I'm showing a 5-7 psi increase in pressure at 3k rpm where the bypass is fully closed, when going from 20W to 40W oil. The pressure increase is due to the increased resistance encountered by the heavier oil flowing though passages and bearings. This pressure increase will serve to open the bypass earlier than with the lighter oil meaning that the maximum flow achieved will be lower than the 20 W from that point on.

Of course, as Paul points out, the hydrodynamic properties of the oil are not to be neglected and there have been many good discussions as to why the ~40W oils are better in this regard than 20W. As a minor point perhaps, stupendously huge flow, that you would get at say 500 psi, would also destroy bearing lubrication properties.

Yeah, I thimk two much! Meds help ....

With a fully warmed engine, I'm showing a 5-7 psi increase in pressure at 3k rpm where the bypass is fully closed, when going from 20W to 40W oil. The pressure increase is due to the increased resistance encountered by the heavier oil flowing though passages and bearings. The flow in that case is identical. Now increase rpm, until the bypass just starts to open with the 40W at 80 psi. At that same rpm, the pressure is just ~73 psi. Now increase rpm until the 20W oil is reading 80 psi. That difference in rpm represents increased flow in the 20W case but no increased for the 40W case. Based on that ~10% difference in rpm, I'd estimate the flow resistance for the 40W is about 10% higher than for the 20W at full operating temperatures.

Only got 1 15w50 Mobil1 Left.

Hmm, need to order some new oil ...

should I try Eneos, or Idemitsu ? ... hmm ...

I think I understand what you are saying ole hard thinker!
You are getting max oil pressure at 4-5K? We havent seen that at oil temps of 180F and above. Me thinks it is over 6K that the max pressure is being seen here at the above temps.
True in that the oem bypass pressure will be reached sooner with a higher viscosity of oil OR a cooler oil temp(which affects the viscosity etc) and since we have a pressure regulated system it would be very lodgical to say that if the regulator opens sooner then there will be less flow since the bypass is dumping. But is that all that happens?
I think also you have to consider that the oil pump with the higher viscosity oil can produce more overall pressure? Would that not change things?

Let me preach on it...........:Eyecrazy:

Ok if with a 20 w oil the bypass doesnt open for example until 6K but the 40W will open at 5K--If I am understanding correctly what you are saying is from 5K to 6K there would be in comparison less oil flow/volume pumping between 5-6K?
If that is a correct interprtation then I believe one thing has not been remembered. The 40 w oil example will increase in pressure between 5-6K even though the by pass has been cracked open. Once again it is not an on/off valve--its a gradual opening. The overall pressure increase the 40 w allows the pump to make provides makes up for the earier bypass opening?
Does that make sense.
More meds---Jeez.:)

Let's try this, though I have to make up some data. At a relatively steady 208F/203F the oil pressures vs rpm with the mazmart mod are:

rpm.....40Wpsi......20Wpsi
----.....--------......--------
900.......18..............17
3000.....60..............53
4000.....72.............(64)
5000.....87.............(78)
6000.....94.............(84)

The () data are a guess. I wish I'd measured it, but too late for the moment. (Data anyone?) Assuming the stock bypass regulates to 80 psi, this chart for the stock system would look like:

rpm.....40Wpsi......20Wpsi
----.....--------......--------
900.......18..............17
3000.....60..............53
4000.....72.............(64)
5000....(80)...........(78)
6000....(80)...........(80)

The 20W is staying in the "good" range of flow longer than the 40W case. Again, flow it not the only thing to consider. With a stock system, I'd have no worries going to 30W, some worries going to 40W, and a lotta worries going to 50W. If I wanted to go to 50W, I'd consider the Mazmart mod mandatory. Just my opinion of course, but every step of this week's working-the-problem seems to say this mod is a really good idea, especially if you want to use heavier weight oils.

Actually the other way around, the vacuum caused by trying to pull the thicker oil into the pump would bring the leakage around the lobes roughly into line with the lower weight oil, but the increase in vacuum = more microcavitation = slightly less oil pumped.

Good point; offsetting penalties. In the absence of measurements, I'd guess that vicosity differences wrt the oil pump itself are rather minor.

I finally see what you are thinking!!!!!!
The tables did it--appreciate the work.
Let me see if i can point out what i am trying to say.
Your table indicates that the max pressure obtained is totally regulated by the bypass. Once the 80psi is reached the pressure cannot go any higher according to the oem table.
What i am saying is that is not entirely true. For example if the bypass is pre set to be fully open at 80psi, with a 40 weight oil our oil pump has the capacity to increase the pressure even more. Not much mind you but some none the less. Its not a direct stop like that.
We both 100% agree though that the Mazmart (Paul's Pump em Up) mod is an extremely good mod to do.!!
olddragger

OD
Can you expand on this thought a little more? It's not clear to me why the pressure would be higher based on different viscosities if the relief valve is fully open at 80psi. Shouldn't the pressure max out at the same level, 80 psi in this case, for any viscosity?

You're likely right, the op will 'sneak up' above the target regulated pressure as the piston valve is overwhelmed with the increased flow from the pump at ~7k+ revs. I wish I'd done more extensive measurements. The highest op I remember seeing with the stock system and warm oil on my gage was about 84 psi at some high rpm which is above the regulated pressure, but not by much. I think we agree we'd rather be seeing 100+ psi that we'll be getting with Paul's magic mod. When he was talking about it back in Nov/Dec, I was fretting about the cost. At $55, he turned this into a major no-brainer. At our advanced age, no-brainers are much appreciated! (Pump em Up) = (Renny Viagra)? :smoker:

It's really hard to convince people that this is of any benefit and most think it's a negative with comments like, "you are going to get oil leaks". Doesn't matter what I say, in their minds, I #@C$%d up by installing this kit. I don't know all the technical details like you guys do. I'm lucky enough to have OD close by so I trust his judgement in a lot of things. I've always hated the lack of oil pressure on this car and when Denny told me about the mod, I couldn't wait to pump it up. So now it's on "viagra" as HiFlite says and seeing the oil pressure riding at 90-100 as I'm driving on the interstate makes me satisfied that lubrication is at a more proper number. So you guys please keep banging out the details and I will just enjoy the ride. Can't wait to see how she reacts when I get her on the track in March at Road Atlanta. I want to know if there is any change in my oil consumption. I'm hoping there is more.

Hiflite---I do love no brainers as that does directly match my intellectual ability:)
Hey---- i know a good example I just remembered. 9K converted from dual coolers to a single cooler and in doing so lost a lot of the bends and turns the oem system has. As a result, that is relative to this conversation, he was able to see 90psi on the oem bypass! Why didnt I remember this before. It would have help unscramble my old brain.

Now back to the mod---glad you agree Don. I to am interested in what is going to be seen in march at Road Atlanta. I have not observed or seen one single negative thing about this mod.
One day young folks are going to start listening to us old timers----------maybe?
OD

This is a short 13 sec vid showing the increased oil pressure. I have more vid but I don't think it's good enough to present. I'm going to shoot more using a camera mount with the entire warm up sequence and a short drive. That should be good enough to bore you to sleep.

http://vimeo.com/9120501

Oh Jeeze, my head has gone loopy :crazy:after reading all the pages of this post!

As a brand new owner of an '06 w/34k miles, this thread scares the hell outta me! :Eyecrazy: Especially since I have no clue of it's oil usage history, but a big 5w-20 written in feminine cursive on the manual cover. Now I'm itchin' to do a compression check! (Oh and when I do a search for more on this topic, I get an overwhelming amount of thread results...if you've got specific stickies and links I'd sure appreciate it!)

Here's my question though...say we do this mod, (which sounds great btw) and up the oil viscosity used, will this void the OEM or additional warranty on the car? While I have confidence I could do this mod easily and correctly, I would still rather it age out gracefully and the OEMs rebuild it, than for me to pay ~6k in parts to rebuild it myself!

Yup, different oil coolers and lines = over 90psi on even a stock system, so the bypass might not be such a huge problem.
Anyhow, the flow doesn't stop increasing when a bypass cracks open, it just increases at a reduced amount.

In Short --- Yes, They will void your warranty BUT ----

There is almost no way to tell if you did this mod or not unless they check your oil pressure with a "real" gauge. or the Tech is smart enough to spot the oil pan gasket area.

So if I were you, I would get a compression test done first. BTW do NOT let the Dealership feed you with a "passed/failed", get the "EXACT" numbers and RPM and post them up here.