Used Oil Analysis - Post Them Here
07-03-2019, 10:15 PM
#951
We all found out years ago about stationary gear wear from light oils.
Those gears are giving you the high chrome readings. I've seen it on other UOA's using 5w20.
I run Mobil 1 0w40.....Chrome is very low as in 9 @7700 miles on my UOA's.
Those gears are giving you the high chrome readings. I've seen it on other UOA's using 5w20.
I run Mobil 1 0w40.....Chrome is very low as in 9 @7700 miles on my UOA's.
07-06-2019, 07:49 PM
#952
77 cylinders, 4 rotors...
0-100,
Did you premix at all when this sample was in service? If so, how much?
Did you premix at all when this sample was in service? If so, how much?
07-06-2019, 07:51 PM
#953
77 cylinders, 4 rotors...
I believe the iron is from the gears, and the chrome is from the housings.
07-08-2019, 08:23 AM
#954
Registered
I went all out on the RP brand just to be a guinea pig, and plan on staying with it for some time. I'll keep uploading oil reports as I do my changes and send it off for analysis. I've been using the RP 5w-20, RP oil filter, and their 2 stroke oil in the gas tank (was doing ~8oz per fillup, but have reduced to ~4 for DD). Within the next month, I plan to get my Sohn kit installed too. My next oil change will be around 5k miles. It should also be noted just for note's sake that I'm not doing a complete oil flush, just the regular oil pan drain and filter change. Some time down the road, I'd like to get some filter mags, just to see if it makes any difference in the oil report. Not that it's going to save my dying engine, but I'm happy to try things.
The following 2 users liked this post by Steve Dallas:
Loki (07-09-2019),
UnknownJinX (07-09-2019)
07-09-2019, 12:14 PM
#956
Smoking turbo yay
07-09-2019, 09:29 PM
#957
77 cylinders, 4 rotors...
0-100,
Thanks for the reply. Thanks for posting your UOA as well.
Off of the immediate topic of your UOA, something I have noticed with these UOAs is that the Renesis seems to not prefer long drain intervals.
The fact that the coolers retain so much oil, so really you are only getting about a 65-75% refresh of the oil with each change, is only one factor.
The other I have been thinking about is in the OMP system. Many of us want the cleanest oil possible in the rotor chambers, and motor oil burns poorly as it is, so the less impurities and unburnable gunk the better. Plus nobody wants a clogged oil injector, leaking one way valve, etc, so clean oil is better here too.
But also, the OMP when stock, injects miniscule amounts of oil. If it is injecting dirty oil, with non-lubricating solids, etc., that OMP effective oil quantity is dropping constantly during the oil change interval, since the OMP is injecting the same tiny volume of liquid oil, but now the oil is composed of a greater and greater percentage of solids, non lubricating liquids, etc. most of which oil analysis doesn't test for (soot, for example).
The oil film in the rotor chamber is small, measured in microns in many places, so these non lubricating components become a much bigger factor for rotary engines than for piston engines. The oil can easily get 10-15%+ contaminated over an interval with all kinds of things. Look at the color change in used oil. Many say that doesn't matter, which could be true in a piston engine, but those don't have oil injection.
Some of that is stuff causing the color change has no lubrication value at all, and is probably a wear contributor. I would not like to think I am effectively reducing the tiny stock OMP output by 10-15% or more by injecting dirty oil. The stationary gears also have a much greater shearing effect than what is found in other modern car engines.
Long drain intervals are do-able in many modern cars, and the current automotive fashion is for thin oils and long intervals, which in my opinion may or may not be proven optimal over time, even in those engines, designed from the start for that style of maintenance.
The RX8 does not have, in my opinion, a "long drain" oil system. In fact, it could be said it is actually a "short-drain" system by current conventions and sensibilities, much shorter than anyone would consider "proper" these days. Comments welcome. Hopefully I didn't hijack this thread.
Thanks for the reply. Thanks for posting your UOA as well.
Off of the immediate topic of your UOA, something I have noticed with these UOAs is that the Renesis seems to not prefer long drain intervals.
The fact that the coolers retain so much oil, so really you are only getting about a 65-75% refresh of the oil with each change, is only one factor.
The other I have been thinking about is in the OMP system. Many of us want the cleanest oil possible in the rotor chambers, and motor oil burns poorly as it is, so the less impurities and unburnable gunk the better. Plus nobody wants a clogged oil injector, leaking one way valve, etc, so clean oil is better here too.
But also, the OMP when stock, injects miniscule amounts of oil. If it is injecting dirty oil, with non-lubricating solids, etc., that OMP effective oil quantity is dropping constantly during the oil change interval, since the OMP is injecting the same tiny volume of liquid oil, but now the oil is composed of a greater and greater percentage of solids, non lubricating liquids, etc. most of which oil analysis doesn't test for (soot, for example).
The oil film in the rotor chamber is small, measured in microns in many places, so these non lubricating components become a much bigger factor for rotary engines than for piston engines. The oil can easily get 10-15%+ contaminated over an interval with all kinds of things. Look at the color change in used oil. Many say that doesn't matter, which could be true in a piston engine, but those don't have oil injection.
Some of that is stuff causing the color change has no lubrication value at all, and is probably a wear contributor. I would not like to think I am effectively reducing the tiny stock OMP output by 10-15% or more by injecting dirty oil. The stationary gears also have a much greater shearing effect than what is found in other modern car engines.
Long drain intervals are do-able in many modern cars, and the current automotive fashion is for thin oils and long intervals, which in my opinion may or may not be proven optimal over time, even in those engines, designed from the start for that style of maintenance.
The RX8 does not have, in my opinion, a "long drain" oil system. In fact, it could be said it is actually a "short-drain" system by current conventions and sensibilities, much shorter than anyone would consider "proper" these days. Comments welcome. Hopefully I didn't hijack this thread.
Last edited by kevink0000; 07-09-2019 at 11:07 PM. Reason: paragraphs
07-10-2019, 09:26 PM
#958
Theory is fine, but ask some of those 200k mile RX8 owners what they did, and some will say nothing.
No premix, no sohn........but used a quart oil every 1k miles.
I see nothing wrong with engine oil omp if it gets to 200k miles.
No premix, no sohn........but used a quart oil every 1k miles.
I see nothing wrong with engine oil omp if it gets to 200k miles.
07-12-2019, 03:52 PM
#959
77 cylinders, 4 rotors...
Some clarification:
My post was involving drain intervals, not deleting the OMP. I use the OMP in my car.
The OMP can be made to work, in my opinion, especially in a street engine, even in the S1, with the two injectors. I am not saying the OMP is not good, its usage in this engine is flawed, due to emissions concerns. I don't feel 200k is an adequate lifespan. Something is amiss, in my opinion, if that is the max.
200k miles seems to be the uppermost limit for this engine. Most fail before that, well before that. And, I would find it hard to believe that the 200k engines are not down on compression and power, significantly, so really the max life is less.
My other point is that this engine outlasts piston engines in a racing environment. Some builders' engines can last 3-4 times as long as piston engines, even with factory components, (Drummond, for one), and making more power than a stock street car. Also, when rotary engines, even the Renesis, are used in aircraft, the Time Between Overhaul is much greater than what a comparable piston engine will achieve. Those run at 75-100% power for the duration of their lives.
So, why not on the street? The power needs and subsequent stress are much less. The Renesis should last longer than a comparable piston engine on the street at least as well as it does in the two high stress environments listed above. Why doesn't it?
My post was involving drain intervals, not deleting the OMP. I use the OMP in my car.
The OMP can be made to work, in my opinion, especially in a street engine, even in the S1, with the two injectors. I am not saying the OMP is not good, its usage in this engine is flawed, due to emissions concerns. I don't feel 200k is an adequate lifespan. Something is amiss, in my opinion, if that is the max.
200k miles seems to be the uppermost limit for this engine. Most fail before that, well before that. And, I would find it hard to believe that the 200k engines are not down on compression and power, significantly, so really the max life is less.
My other point is that this engine outlasts piston engines in a racing environment. Some builders' engines can last 3-4 times as long as piston engines, even with factory components, (Drummond, for one), and making more power than a stock street car. Also, when rotary engines, even the Renesis, are used in aircraft, the Time Between Overhaul is much greater than what a comparable piston engine will achieve. Those run at 75-100% power for the duration of their lives.
So, why not on the street? The power needs and subsequent stress are much less. The Renesis should last longer than a comparable piston engine on the street at least as well as it does in the two high stress environments listed above. Why doesn't it?
07-12-2019, 04:38 PM
#960
Smoking turbo yay
Street and track are not comparable. At all. Toyota has the exact opposite problem: their hybrid technology is tried and true on the street with Prius and Camry/RAV4 hybrid. On the track? Look how many tries it took them to win LeMans, and when they finally managed it, it was lucky because Porsche decided to pull out.
The main difference is that everything that goes on a track is running constantly at a high load and high RPM situation, and they are maintained and checked like crazy. Same with aircraft, they have a fairly constant load when cruising and you can't "pull over" in the air as easily so they have to go through a lot of maintenance and checks. I assume they also go through heat cycles less than a DD street car.
And I sound like a broken record now, but once again, Mazda's R&D for the rotary is actually quite odd. I get that having your entire lineup use rotary is not realistic (especially for pickups and a 26-seat bus), but reserving it only to sports cars is also not smart. They only got away with it because of the bubble economy. This is why I support the rotary range extender - it's the only way for rotaries to get the much needed R&D money.
The main difference is that everything that goes on a track is running constantly at a high load and high RPM situation, and they are maintained and checked like crazy. Same with aircraft, they have a fairly constant load when cruising and you can't "pull over" in the air as easily so they have to go through a lot of maintenance and checks. I assume they also go through heat cycles less than a DD street car.
And I sound like a broken record now, but once again, Mazda's R&D for the rotary is actually quite odd. I get that having your entire lineup use rotary is not realistic (especially for pickups and a 26-seat bus), but reserving it only to sports cars is also not smart. They only got away with it because of the bubble economy. This is why I support the rotary range extender - it's the only way for rotaries to get the much needed R&D money.
07-13-2019, 07:12 PM
#961
Seals are reason rotary doesn't last longer.
Pistons actually slow down, and have some oil dripping off them.
At least rotary usually doesn't shell out all at once, so you might get home.
Pistons actually slow down, and have some oil dripping off them.
At least rotary usually doesn't shell out all at once, so you might get home.
07-13-2019, 08:23 PM
#962
Some clarification:
My other point is that this engine outlasts piston engines in a racing environment. Some builders' engines can last 3-4 times as long as piston engines, even with factory components, (Drummond, for one), and making more power than a stock street car. Also, when rotary engines, even the Renesis, are used in aircraft, the Time Between Overhaul is much greater than what a comparable piston engine will achieve. Those run at 75-100% power for the duration of their lives.
My other point is that this engine outlasts piston engines in a racing environment. Some builders' engines can last 3-4 times as long as piston engines, even with factory components, (Drummond, for one), and making more power than a stock street car. Also, when rotary engines, even the Renesis, are used in aircraft, the Time Between Overhaul is much greater than what a comparable piston engine will achieve. Those run at 75-100% power for the duration of their lives.
The other thing is aviation (or racing) rotaries aren't attached to a cat which is, what, 50+% of the root cause observed on this forum?
The other other thing is someone building an engine (any engine) for racing or aviation is far more likely to maintain proper clearances, temperatures and tuning for the intended usecase. Random RX8 owner is lucky to keep an eye on 1 of those things.
The other other other thing is carbon build-up and other inherent problems manifest in low load situations like sitting in traffic or waiting at a red light. Racing/aviation rotaries don't experience any of that.
All that to say that sure, they might be reliable in high rev, high vigilance environments, but clearly thousands of kilometers of street driving are not a good comparison.
Automotive rotaries don't die of exhaustion, they die of boredom.
Last edited by Loki; 07-13-2019 at 08:48 PM.
07-17-2019, 05:55 AM
#964
1% evil, 99% hot gas.
iTrader: (21)
That's what makes the Wankel Rotary special. What reciprocation can't do, extreme rotation can!
The Mazda Mantra:
A Redline A Day Keeps The Mechanic Away!
If you drive a boinger like you stole it every day, it will not last.
If you don't drive a Mazda rotary like you stole it every day, it will not last! (See automatics all dying young.)
.
The Mazda Mantra:
A Redline A Day Keeps The Mechanic Away!
If you drive a boinger like you stole it every day, it will not last.
If you don't drive a Mazda rotary like you stole it every day, it will not last! (See automatics all dying young.)
.
07-18-2019, 07:48 AM
#965
Water Foul
My Miata has 75K on the clock, where 30K are track miles. Runs like new.
Anyway, we are getting off topic here...
11-22-2019, 11:01 AM
#967
You've certainly had a good run, and looks like the 10k mile oil change didn't even hurt it.
What's hurting in there is the stationary gears getting de-chromed.
It's been discussed before about the thin 5w20 not being enough for gears.
Gears in transmission end up with similar to 50 weight engine oil. (90 weight gear=50 weight engine)
I use 0w40 in my engine.
What's hurting in there is the stationary gears getting de-chromed.
It's been discussed before about the thin 5w20 not being enough for gears.
Gears in transmission end up with similar to 50 weight engine oil. (90 weight gear=50 weight engine)
I use 0w40 in my engine.
11-22-2019, 11:59 AM
#969
77 cylinders, 4 rotors...
My opinion of the location of the major wear elements is as follows:
Iron=stationary and rotor gears
Chrome= housing surface
I believe the loss of viscosity in these engines is fundamentally shearing from the action of the rotor and stationary gears. They do tend to shear oils fairly quickly as if there was some reasonably significant load on the gears, hence the assumption that the iron wear particles are primarily from those gears. Apex seal wear also, for the reason below.
The "chrome farm" is the housing coating in my opinion. Vast chrome plated surface area exposed to wiping motion of the apex seals combined with minimal or inadequate lubrication. Not all of it goes out the exhaust.
Iron=stationary and rotor gears
Chrome= housing surface
I believe the loss of viscosity in these engines is fundamentally shearing from the action of the rotor and stationary gears. They do tend to shear oils fairly quickly as if there was some reasonably significant load on the gears, hence the assumption that the iron wear particles are primarily from those gears. Apex seal wear also, for the reason below.
The "chrome farm" is the housing coating in my opinion. Vast chrome plated surface area exposed to wiping motion of the apex seals combined with minimal or inadequate lubrication. Not all of it goes out the exhaust.
11-22-2019, 12:38 PM
#970
Of course, I could be wrong.........but it seems every UOA has high chrome with 5w20.
Any chrome on shaft or bearings?
OP of UOA got good life of car so far, and it probably won't be oil related death anyway.
First 10k mile UOA had raised potassium and sodium which could be slight coolant.
Any chrome on shaft or bearings?
OP of UOA got good life of car so far, and it probably won't be oil related death anyway.
First 10k mile UOA had raised potassium and sodium which could be slight coolant.
11-22-2019, 01:13 PM
#971
Registered
Yeah I figured it was the housings, since this engine has 135k miles on it. With the poor-ish compression, it wouldn't surprise me a bit if that's where the chrome readings are coming from. Does anyone know where titanium or magnesium would come from?
I think I'll keep going with the 5w-20 for the rest of the year, get some more reports for more data points, and then if the engine hasn't died yet, I'll try a heavier weight oil and see if it makes a noticeable difference.
I think I'll keep going with the 5w-20 for the rest of the year, get some more reports for more data points, and then if the engine hasn't died yet, I'll try a heavier weight oil and see if it makes a noticeable difference.
11-23-2019, 08:56 AM
#974
That iron is a low number for these engines and that mileage.
The oil looks like good stuff, although it would be good to know how much silicon is in virgin oil.
Mobil 1 0w40 starts out with approx 7 silicon from silicone. 12 ppm of silicon from dirt is limit, so Mobil 1 0w40 could have 19 as upper limit.
The oil looks like good stuff, although it would be good to know how much silicon is in virgin oil.
Mobil 1 0w40 starts out with approx 7 silicon from silicone. 12 ppm of silicon from dirt is limit, so Mobil 1 0w40 could have 19 as upper limit.
11-25-2019, 02:47 PM
#975
Registered
Just for S&G's, I sent off a sample of my transmission fluid too, which was Redline MT-90. After that drain, I put in Enos 75W-90. I just want to see if there'd be some major difference between the two.
