Renesis OIL PRESSURE Discussion with Dealer Tech
12-10-2009, 11:35 AM
#876
SARX Legend
iTrader: (46)
It is sad but I would say that most 8 owners do not add oil between changes on a regular basis or check their oil at fill-ups.. A friend of mine and I were actually discussing this after the last statewide meet. We only saw a couple of guys check oil throughout the day during hard driving. Personally, my car has always drank a lot of oil even through different motors and at the end of the day I was down a quart and during one of the frequent stops I only noticed one other guy checking his oil and we both commented on it.
Now mind you that the majority of the guys at the statewide meet and the guys visiting this site should be more likely to check their oil than the average non enthusiast type owner.
Now mind you that the majority of the guys at the statewide meet and the guys visiting this site should be more likely to check their oil than the average non enthusiast type owner.
12-10-2009, 11:36 AM
#877
oil addition does affect things but even with that via the eoa's its not enough.
One thing to remember about draining the oil coolers/lines. if you do that you are leaving a rather large space with no oil present. So when the engine starts it will have a brief period of no oil being sent to the engine. Same priciple that applies to the oil filter.
I relocated my oil filter and inverted it so i can fill it when i change my oil. There were other reasons also but this was also one of the reasons i did this.
OD
One thing to remember about draining the oil coolers/lines. if you do that you are leaving a rather large space with no oil present. So when the engine starts it will have a brief period of no oil being sent to the engine. Same priciple that applies to the oil filter.
I relocated my oil filter and inverted it so i can fill it when i change my oil. There were other reasons also but this was also one of the reasons i did this.
OD
12-10-2009, 03:49 PM
#878
oil addition does affect things but even with that via the eoa's its not enough.
One thing to remember about draining the oil coolers/lines. if you do that you are leaving a rather large space with no oil present. So when the engine starts it will have a brief period of no oil being sent to the engine. Same priciple that applies to the oil filter.
I relocated my oil filter and inverted it so i can fill it when i change my oil. There were other reasons also but this was also one of the reasons i did this.
OD
One thing to remember about draining the oil coolers/lines. if you do that you are leaving a rather large space with no oil present. So when the engine starts it will have a brief period of no oil being sent to the engine. Same priciple that applies to the oil filter.
I relocated my oil filter and inverted it so i can fill it when i change my oil. There were other reasons also but this was also one of the reasons i did this.
OD
12-10-2009, 03:52 PM
#879
Just a thought.. perhaps, the full drain, for lack of a better description, would be advantageous if used in conjunction with AMSOIL's suggested extended drain interval, so that the pronounced startup oil starvation would only occur during the full drain and fill.
My understanding is that if a full drain is not done that they do not recommend extended drain intervals even with their oil, because there's too much risk of contamination with worn out oil.
My understanding is that if a full drain is not done that they do not recommend extended drain intervals even with their oil, because there's too much risk of contamination with worn out oil.
12-10-2009, 06:49 PM
#880
Registered User
Join Date: Apr 2009
Location: michigan
Posts: 239
Likes: 0
Received 0 Likes
on
0 Posts
I'm with 9k in assuming that most people do *not* check their oil - probably ever! With nearly 100k RX-8s sold, this is not that hard to believe as most people who buy the car unfortunately are not enthusiasts... They just think it "looks cool" (don't get me wrong - it does!).
Even if mazda provided provisions for performing a complete oil change, it would for the most part never be performed properly anyways, as apparently simply removing and replacing the oil pan plug isn't simple enough for many.
I'm also a huge proponent of pre-lubers on *any* car, which allows for almost complete elimination of cold start wear. A properly setup unit in the RX-8 could also be used to aid oil evacuation for changes, and also prime the system before a start. If you're really serious about your oil changes, and cold start protection, this is the only way to go, imho.
Even if mazda provided provisions for performing a complete oil change, it would for the most part never be performed properly anyways, as apparently simply removing and replacing the oil pan plug isn't simple enough for many.
I'm also a huge proponent of pre-lubers on *any* car, which allows for almost complete elimination of cold start wear. A properly setup unit in the RX-8 could also be used to aid oil evacuation for changes, and also prime the system before a start. If you're really serious about your oil changes, and cold start protection, this is the only way to go, imho.
12-10-2009, 10:09 PM
#881
SARX Legend
iTrader: (46)
Funny you mention Pre-Oilers. We have discussed it a bit but no one was really with me in thinking along those lines. I'm not sure if it is a viable option but I think it is worth some research.
12-11-2009, 02:25 AM
#882
Registered User
Join Date: Apr 2009
Location: michigan
Posts: 239
Likes: 0
Received 0 Likes
on
0 Posts
That's a very nice looking pump, 9k.. There are tons out there - a simple google search of "oil preluber" does the trick. There are also non-specific pumps out there for us DIYers.
For those of you interested in just the aspects of pressurizing your oil system just prior to start-up, I found a very simple (cheap) setup online a while back (unfortunately I can't find the link anymore). You basically need a container (preferably metal of some sort) that can hold up to 100psi, a solenoid valve, and some oil hose. You basically connect the oil hose somewhere on the pressurized side of the oiling system (like the sandwich plate), run the other end to the solenoid valve, and then the other side of the valve to the canister. While the engine is running, you open the valve (from wherever you wire the switch - ideally inside the car, lol), which in turn forces oil into the bottle at operating pressure. Then, while the engine is still running, you shut the valve - this locks the oil in the canister under pressure. Then the next time right before you start the engine, you open up the valve and immediately start the engine. You then repeat the steps for the next time around.
Of course, an actual electric pump is more flexible, and ideal.
For those of you interested in just the aspects of pressurizing your oil system just prior to start-up, I found a very simple (cheap) setup online a while back (unfortunately I can't find the link anymore). You basically need a container (preferably metal of some sort) that can hold up to 100psi, a solenoid valve, and some oil hose. You basically connect the oil hose somewhere on the pressurized side of the oiling system (like the sandwich plate), run the other end to the solenoid valve, and then the other side of the valve to the canister. While the engine is running, you open the valve (from wherever you wire the switch - ideally inside the car, lol), which in turn forces oil into the bottle at operating pressure. Then, while the engine is still running, you shut the valve - this locks the oil in the canister under pressure. Then the next time right before you start the engine, you open up the valve and immediately start the engine. You then repeat the steps for the next time around.
Of course, an actual electric pump is more flexible, and ideal.
12-11-2009, 02:45 AM
#883
Ayrton Senna Forever
Both of these statements are incorrect, if you go read the literature. Pressure does not affect film strength.
And, there is a difference between 5w20 and the higher viscosities under high temp, high shear conditions. It's called the HTHS spec - read up on it.
However, you are correct that a higher flow rate should keep the oil from heating up as much while in the bearing.
I believe the main reasons for the changes to the S2 are to make it more freindly for the typical consumer. An extra oil injecter to remove the need to premix, and higher flow rate to make 5w20 more viable.
I do agree the lower pressure at low rpm is a curiosity in the S1, but as long as there is enough flow to keep the bearing fed, there shouldn't be an issue. The rpms are low enough that there shouldn't be an issue with excessive heat, therefore the flow rate isn't critical.
And, there is a difference between 5w20 and the higher viscosities under high temp, high shear conditions. It's called the HTHS spec - read up on it.
However, you are correct that a higher flow rate should keep the oil from heating up as much while in the bearing.
I believe the main reasons for the changes to the S2 are to make it more freindly for the typical consumer. An extra oil injecter to remove the need to premix, and higher flow rate to make 5w20 more viable.
I do agree the lower pressure at low rpm is a curiosity in the S1, but as long as there is enough flow to keep the bearing fed, there shouldn't be an issue. The rpms are low enough that there shouldn't be an issue with excessive heat, therefore the flow rate isn't critical.
..And it seems we haven't got enough flow at high rpm even for 50w oil. But it is a long story.
12-11-2009, 02:47 AM
#884
Super Moderator
Thread Starter
Sounds like the similar operational procedure as used in the S2 two EMOP's
That's a very nice looking pump, 9k.. There are tons out there - a simple google search of "oil preluber" does the trick. There are also non-specific pumps out there for us DIYers.
For those of you interested in just the aspects of pressurizing your oil system just prior to start-up, I found a very simple (cheap) setup online a while back (unfortunately I can't find the link anymore). You basically need a container (preferably metal of some sort) that can hold up to 100psi, a solenoid valve, and some oil hose. You basically connect the oil hose somewhere on the pressurized side of the oiling system (like the sandwich plate), run the other end to the solenoid valve, and then the other side of the valve to the canister. While the engine is running, you open the valve (from wherever you wire the switch - ideally inside the car, lol), which in turn forces oil into the bottle at operating pressure. Then, while the engine is still running, you shut the valve - this locks the oil in the canister under pressure. Then the next time right before you start the engine, you open up the valve and immediately start the engine. You then repeat the steps for the next time around.
Of course, an actual electric pump is more flexible, and ideal.
For those of you interested in just the aspects of pressurizing your oil system just prior to start-up, I found a very simple (cheap) setup online a while back (unfortunately I can't find the link anymore). You basically need a container (preferably metal of some sort) that can hold up to 100psi, a solenoid valve, and some oil hose. You basically connect the oil hose somewhere on the pressurized side of the oiling system (like the sandwich plate), run the other end to the solenoid valve, and then the other side of the valve to the canister. While the engine is running, you open the valve (from wherever you wire the switch - ideally inside the car, lol), which in turn forces oil into the bottle at operating pressure. Then, while the engine is still running, you shut the valve - this locks the oil in the canister under pressure. Then the next time right before you start the engine, you open up the valve and immediately start the engine. You then repeat the steps for the next time around.
Of course, an actual electric pump is more flexible, and ideal.
12-11-2009, 04:03 AM
#885
If it's a combination of the oil coolers being too low to drain properly in combination with the apparently borderline 5W20, then it seems that Mazda ought to have included some manner of drain plug or tap at the bottom of the coolers. Naturally, we can achieve a similar effect by either using a single high-mounted cooler in lieu of the OE coolers or by alternately lifting one side and then the other while draining during an oil change. Certainly, the 5W20 has little additional capacity; but having a system where a significant percentage of worn out oil is still trapped in the system has got to be asking for trouble. Indeed, if this (the positioning of the oil coolers and the trapping of old oil in them during an oil change) is the root cause, then it explains why even Auto transmission models are impacted, as, if anything, the Autos would be less likely to fully warm up the oil and vaporize volatile contaminants, whether from blow by or decomposition, allowing them to be inhaled from the "crankcase" breather and burned off.
https://www.rx8club.com/showthread.p...&highlight=oil
beers
12-11-2009, 11:43 AM
#888
Huh?
front stationary gear bearing wear on previous rotory engines are the same as ours?
Others, including myself, do not think that.
you are right---- pressure is not the problem--oil flow and film strenght (for some) is.
heat can be a problem but not here.
OD
front stationary gear bearing wear on previous rotory engines are the same as ours?
Others, including myself, do not think that.
you are right---- pressure is not the problem--oil flow and film strenght (for some) is.
heat can be a problem but not here.
OD
The following users liked this post:
WayneBrady (12-31-2021)
12-11-2009, 12:01 PM
#889
Are you sure about that? High rpm operation can result in high, localized heating. Which is to say, the peak temp of the oil while in the bearing, at, say, 8,500 rpm, may be significantly higher than the peak temp your gauge shows you.
I think this disucssion illustrates the difference between what we know and what we suspect.
I think this disucssion illustrates the difference between what we know and what we suspect.
12-11-2009, 12:42 PM
#890
Are you sure about that? High rpm operation can result in high, localized heating. Which is to say, the peak temp of the oil while in the bearing, at, say, 8,500 rpm, may be significantly higher than the peak temp your gauge shows you.
I think this disucssion illustrates the difference between what we know and what we suspect.
I think this disucssion illustrates the difference between what we know and what we suspect.
At this point, I'm leaning heavily towards a combination of dirty/worn out oil being trapped in the system and viscosity that is marginal when new and completely insufficient when worn out (hence why it is so bad to have it carried over into the next oil change interval instead of getting it fully drained out).
I am still interested in a pressure increase, even if it might be complete overkill for my needs (and I concede that it probably is overkill).
12-11-2009, 02:33 PM
#892
Also, if heat were not an issue for bearing failure (we know it is an issue at large, based on the number of failures in hotter climates, and/or AT failures) then there would be no reason to increase flow over the bearing. Unless of course one believes the current design starves the bearing, which strikes me as highly unlikely.
12-11-2009, 05:28 PM
#894
Registered
Join Date: Apr 2004
Location: Long Beach, CA
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
Seals and heat
What cools the Apex, corner, side and oil control rings is OIL.
The oil that is sprayed inside the rotors.
I can get the oil temps up to and past 240 without ever going over 4K rpm.
What is biggest difference between the RX8 and the second gen RX7?
1-The oil coolers (less cooling).
2-About 80 more horse power (More Heat).
3-Oil injector placement
What's the same between the RX8 and the stock third gen RX7?
1-The oil coolers (less cooling).
2-25 HP less (almost the same heat).
The FD's have all kinds of HEAT problems, always have. (External and internal)
The RX8 has very similar internal heat as the FD. (RX8 220-230 HP of heat, FD 255 of heat, FC 160).
The bearings out of my motor at 97K miles (with 5x20 oil) looked just like most of the bearings I looked at. There was all kinds of evidence of oil heat with the apex seals and the oil control rings (the rubber o-rings came out in peaces)
The way I see it is 5x20 oil is no good for the RX8 (or any other Rotary).
My second motor has only seen 10x40 and premix from day one.
No air to the oil coolers means no cooling (RX8, FD same problem)
The second gen and below always got air to the oil coolers (mech fan).
Oil injector placement as we know is not good. Premix is a must!!!!! (09 is OK)
The oil that is sprayed inside the rotors.
I can get the oil temps up to and past 240 without ever going over 4K rpm.
What is biggest difference between the RX8 and the second gen RX7?
1-The oil coolers (less cooling).
2-About 80 more horse power (More Heat).
3-Oil injector placement
What's the same between the RX8 and the stock third gen RX7?
1-The oil coolers (less cooling).
2-25 HP less (almost the same heat).
The FD's have all kinds of HEAT problems, always have. (External and internal)
The RX8 has very similar internal heat as the FD. (RX8 220-230 HP of heat, FD 255 of heat, FC 160).
The bearings out of my motor at 97K miles (with 5x20 oil) looked just like most of the bearings I looked at. There was all kinds of evidence of oil heat with the apex seals and the oil control rings (the rubber o-rings came out in peaces)
The way I see it is 5x20 oil is no good for the RX8 (or any other Rotary).
My second motor has only seen 10x40 and premix from day one.
No air to the oil coolers means no cooling (RX8, FD same problem)
The second gen and below always got air to the oil coolers (mech fan).
Oil injector placement as we know is not good. Premix is a must!!!!! (09 is OK)
12-11-2009, 08:39 PM
#895
Super Moderator
Thread Starter
No air to the oil coolers means no cooling (RX8, FD same problem)
Winter time I will go back to OEM shields as I believe the oil will be too cold.
And I totally agree that ANY 5W20 engine oil is no good for ANY rotary..
If you are comparing second gen RX-7 (FC) Oil Coolers to the RX-8 (with Twin OC's) IMO I believe the RX-8 has a larger surface area when you combine both 8 coolers compared to the single under radiator one of the FC.
It still baffles me 'WHY' Mazda did not Lube the middle of the Apex Seals in S1 RX-8's, surely long term testing would have shown irregular wear in the middle of the Apex Seal?.
I was told by a Mazda Australian long time worker that Mazda did a lot of Cold weather and Snow testing, but almost NO Hot Climate testing apart from Lab testing!..
Normally they would tests in Nevada or outback Australia for Heat and Dust related data.
12-11-2009, 09:03 PM
#897
oh i see what you are speaking about.
we have been speaking mainly about the bearings. In speaking of the bearings heat doesnt seem to be a problem. E shafts are clean without heat marks, etc here is a picture of an overheated flat bearing. this we are not seeing.
http://foreignaffairs.us/gallery/alb...jiffieweld.jpg
dino oil is good up to about 250F
I have never seen 240F oil temp on my car--even on a 105F day and the pavement was 150F.
I have seen 210F but no higher ( i have cooling mods) and that was only once. usually it is well below 200F--yet on 2 engines i have had the front bearing wear.
Now heat concerns in other parts of the engine---yes-- especially side seals , but that is another story.
totally agree on a heavier wgt oil--i think all of us do and pre mix too.
od
we have been speaking mainly about the bearings. In speaking of the bearings heat doesnt seem to be a problem. E shafts are clean without heat marks, etc here is a picture of an overheated flat bearing. this we are not seeing.
http://foreignaffairs.us/gallery/alb...jiffieweld.jpg
dino oil is good up to about 250F
I have never seen 240F oil temp on my car--even on a 105F day and the pavement was 150F.
I have seen 210F but no higher ( i have cooling mods) and that was only once. usually it is well below 200F--yet on 2 engines i have had the front bearing wear.
Now heat concerns in other parts of the engine---yes-- especially side seals , but that is another story.
totally agree on a heavier wgt oil--i think all of us do and pre mix too.
od
12-12-2009, 03:26 AM
#898
Registered
Join Date: Dec 2007
Location: UK
Posts: 863
Likes: 0
Received 0 Likes
on
0 Posts
It's not the bearing overheating that they are talking about - it's the oil in the bearing under the pressure and shearing loads experienced there, which does cause localised heating of the oil, which would drop the viscosity in the bearing even more (although because the feed oil would still be the same visc., wouldn't result in a corresponding flow increase apart from faster flow out of the bearing, which isn't good, obviously).
As I've said before, I think there's a little of this going on, as the oil reports are showing thinning on the lower weight oils - which should actually be more stable at keeping in viscosity than a higher weight oil, which is why you tend to aim for the lowest weight oil you can use in any circumstances - so the only explaination is that they are shearing under high temperature + pressures.
I'm certainly quite happy with the condition of mine with 30 weight anyway, time will tell what it's like as we'll strip it down again next summer for a check over.
As I've said before, I think there's a little of this going on, as the oil reports are showing thinning on the lower weight oils - which should actually be more stable at keeping in viscosity than a higher weight oil, which is why you tend to aim for the lowest weight oil you can use in any circumstances - so the only explaination is that they are shearing under high temperature + pressures.
I'm certainly quite happy with the condition of mine with 30 weight anyway, time will tell what it's like as we'll strip it down again next summer for a check over.
12-12-2009, 08:41 AM
#899
oh ok--i see what you are talking about--understand and agree. correct viscosity all important to keep the needed film strength so shearing loads are not breached. Actual bearing temps is something beyond our scope of monitoring. we do keep the oil temps re seasonable.
od
od
12-12-2009, 01:23 PM
#900
What we are seeing with the bearing wear is related to the lack of barrier oil film that is hydrostatic and more viscosity related than anything else. When that is compromised the dirt in suspension and other byproducts of combustion can polish away at the bearings protective layers. When people start off with a low viscosity number in the first place (xW20) then they are begging for trouble in terms of shear and every other type of VI reducing element.
Increased oil pressure addresses other things that I will comment on soon after olddragger reports on our kit.
Paul.
Increased oil pressure addresses other things that I will comment on soon after olddragger reports on our kit.
Paul.