Gas/Oil Premix Thread
10-04-2004 | 02:19 PM
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From: Florida
Gas/Oil Premix Thread
First off, many thanks to rotarygod and deadrx7conv for their past comments on this subject!
I started using premix at 800 miles. I use 8 oz per 10 gallons for a ratio of 160/1.
I saw an immediate increase in MPG from one tank without premix, to the next tank with premix, of 1 1/2 MPG (from 18.5 to 20 MPG, 70/30 highway/city). I currently have 1400 miles on the car, and the MPG before starting the pre-mix use was consistant (+/- 0.5 MPG), as is the milage now, using pre-mix. The engine seems to rev easier, but I may be mistaken on this point (purely subjective). I am using Castrol TCW3 two-stroke outboard oil.
This use of premix is purely supplimental. I plan to drive this RX-8 for many years, and I feel that the rotor seals could use some additional lubrication assistance. Total cost is less than $1 per fill-up.
I spent many years running two-stroke motorcycles on the street, and in the dirt. I am very aware of the importance of combustion chamber lubrication in regards to sealing compression, and giving long life to the sealing surfaces. Four-stroke crankcase oil, of any type, is a poor combustion chamber oil. Two-stroke oil has a strong attraction to metal surfaces, and a lower flash point, compared to most four-stroke oil.
I have decided to straddle the fence in regards to crankcase oil. I am using Mororcraft 5W-20 (Conoco). This is a Group III blend (most oil professionals do not consider a Group III a "true" synthetic), and has had very good reviews on BITOG, including a good UOA on an RX-8. Oil dilution with fuel is the biggest problem with RX-8 UOA's, to this point.
All comments are welcome!
__________________________________________________ _____________________________
Mod Edit: I wasn't a member this early to be able to move a post of my own into the thread for a summary, so tacking on important bits to the opening post here, to make it easier for people to find highlights in the massive thread.
Regarding TCW-3 and why it's not a recommended premix:
I started using premix at 800 miles. I use 8 oz per 10 gallons for a ratio of 160/1.
I saw an immediate increase in MPG from one tank without premix, to the next tank with premix, of 1 1/2 MPG (from 18.5 to 20 MPG, 70/30 highway/city). I currently have 1400 miles on the car, and the MPG before starting the pre-mix use was consistant (+/- 0.5 MPG), as is the milage now, using pre-mix. The engine seems to rev easier, but I may be mistaken on this point (purely subjective). I am using Castrol TCW3 two-stroke outboard oil.
This use of premix is purely supplimental. I plan to drive this RX-8 for many years, and I feel that the rotor seals could use some additional lubrication assistance. Total cost is less than $1 per fill-up.
I spent many years running two-stroke motorcycles on the street, and in the dirt. I am very aware of the importance of combustion chamber lubrication in regards to sealing compression, and giving long life to the sealing surfaces. Four-stroke crankcase oil, of any type, is a poor combustion chamber oil. Two-stroke oil has a strong attraction to metal surfaces, and a lower flash point, compared to most four-stroke oil.
I have decided to straddle the fence in regards to crankcase oil. I am using Mororcraft 5W-20 (Conoco). This is a Group III blend (most oil professionals do not consider a Group III a "true" synthetic), and has had very good reviews on BITOG, including a good UOA on an RX-8. Oil dilution with fuel is the biggest problem with RX-8 UOA's, to this point.
All comments are welcome!
__________________________________________________ _____________________________
Mod Edit: I wasn't a member this early to be able to move a post of my own into the thread for a summary, so tacking on important bits to the opening post here, to make it easier for people to find highlights in the massive thread.
Regarding TCW-3 and why it's not a recommended premix:
I think some things should be clarified, after several PM's between me and STEALTH and doing some online research on TCW-3. It is definitely designed to be burnt and fully combust without leaving any residue or ash (if it is a synthetic ashless oil). It is made WITHOUT any metallic additives, as it is meant to burn ashless it does not contain any.
While it probably wouldn't do any harm to the car (besides the catalyst), the problem with TCW-3 lies within it's lubricating capabilities. It is not as good as an oil at lubricating as a ISO or JASO FC certified oil is. TCW-3 is an oil that is not good enough to lubricate snowmobiles and motorcycle engines, and has lead to failure to those engines that TCW-3 oils were used in. Not because the oil itself caused the failure, it just didn't serve it's purpose in lubricating the bearings and engine parts that needed lubricity, hence the failure.
So what I'm trying to get at is... TCW-3 oils suck as a lubricating oil. A JASO FC and ISO oil would do a much better job. TCW-3 premix is not the worst thing you can put in the car though, it shouldn't harm it, and it should lubricate some what, but it just isn't the best lubricant we would want for our engine; we would want to get the best we could in there. I just wanted to clarify this and explain some of these details, so that people using TCW-3 as premix don't get scared and think that they have potentially harmed their engine by using a oil with metallic particles (not true) that isn't meant to combust in their car (not true as well).
If you were using TCW-3 oils as I was, you should definitely switch to something else like idemitsu or any other 2-cycle oil JASO FC or ISO rated. This is one long assss thread, and reading through it is a pain, but if one does so you would find how contradicting a lot of the information is. I just wanted to make it easier for some people, and so that others don't make the same mistake I and many others have made.
While it probably wouldn't do any harm to the car (besides the catalyst), the problem with TCW-3 lies within it's lubricating capabilities. It is not as good as an oil at lubricating as a ISO or JASO FC certified oil is. TCW-3 is an oil that is not good enough to lubricate snowmobiles and motorcycle engines, and has lead to failure to those engines that TCW-3 oils were used in. Not because the oil itself caused the failure, it just didn't serve it's purpose in lubricating the bearings and engine parts that needed lubricity, hence the failure.
So what I'm trying to get at is... TCW-3 oils suck as a lubricating oil. A JASO FC and ISO oil would do a much better job. TCW-3 premix is not the worst thing you can put in the car though, it shouldn't harm it, and it should lubricate some what, but it just isn't the best lubricant we would want for our engine; we would want to get the best we could in there. I just wanted to clarify this and explain some of these details, so that people using TCW-3 as premix don't get scared and think that they have potentially harmed their engine by using a oil with metallic particles (not true) that isn't meant to combust in their car (not true as well).
If you were using TCW-3 oils as I was, you should definitely switch to something else like idemitsu or any other 2-cycle oil JASO FC or ISO rated. This is one long assss thread, and reading through it is a pain, but if one does so you would find how contradicting a lot of the information is. I just wanted to make it easier for some people, and so that others don't make the same mistake I and many others have made.
Last edited by RIWWP; 09-17-2012 at 11:54 AM.
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GroovieGargoyle (06-25-2017)
10-04-2004 | 04:52 PM
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From: Des Moines, Iowa
Premix: effect on catalytic convert?
What type of negative effect would the premix have on the catalytic converter or passing emission test?
Do you just use normal two stroke chainsaw oil mix, that would be added to the fuel?
Do you just use normal two stroke chainsaw oil mix, that would be added to the fuel?
10-05-2004 | 09:41 PM
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From: Florida
Jaguar MBA: I will discontinue use before emission testing. That is 2 years off, as this is a new car. The oil I use is Castrol TC-W3 Super Outboard oil. The outboard oils rated TC-W3 are formulated to burn with no ash.
ps1726: Thanks for the reply! I see no down side to mix ratios over 100/1. The Renesis motor is designed to burn oil, and the 2-stroke oils are designed to burn without ash or excessive carbon buildup. The 2-stroke motorcycles I ran used mixes in the 40/1 range, and they had very minimal carbon buildup. They also had iginition systems much less advanced than the system on the Renesis.
ps1726: Thanks for the reply! I see no down side to mix ratios over 100/1. The Renesis motor is designed to burn oil, and the 2-stroke oils are designed to burn without ash or excessive carbon buildup. The 2-stroke motorcycles I ran used mixes in the 40/1 range, and they had very minimal carbon buildup. They also had iginition systems much less advanced than the system on the Renesis.
10-06-2004 | 02:23 AM
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From: Houston
I am not against premixing in any way. Here are my thoughts on it though.
The engine already gets oil injected into the combustion chamber to lubricate it. While you don't want too little oil, you also don't want too much. I definitely agree that 2 cycle oil is the best way to go and that standard motor oils suck in the combustion chamber. However, I am not a fan of using oil injection AND premix. Use one or the other. Unfortunately if you disconnect the omp on the RX-8, the car will drive in limp mode. This isn't good.
The engine has different lubrication requirements based on rpm and load. The omp varies the oil into the engine based on this. Premixing leaves you with one set ratio. Typically it is the maximum amount based on max loads and rpm's. This leaves you with too much oil for 99.9% of your driving. Running a really small amount of 2 cycle oil shouldn't be a problem but it also isn't really necessary.
The best overall option is to install an adapter in between the engine and the omp that will let you pick up oil from an outside reservoir. This way you can run 2 cycle oil through the omp system and have it metered in the correct amounts. The engine oil also isn't circulated and now there is zero reason why you can't run synthetics. This is the best option.
Too much oil will hurt performance in the long run. If you still want to run premix with the factory system hooked up, use a higher ratio such as 600:1 or 800:1. Keep it low though.
The engine already gets oil injected into the combustion chamber to lubricate it. While you don't want too little oil, you also don't want too much. I definitely agree that 2 cycle oil is the best way to go and that standard motor oils suck in the combustion chamber. However, I am not a fan of using oil injection AND premix. Use one or the other. Unfortunately if you disconnect the omp on the RX-8, the car will drive in limp mode. This isn't good.
The engine has different lubrication requirements based on rpm and load. The omp varies the oil into the engine based on this. Premixing leaves you with one set ratio. Typically it is the maximum amount based on max loads and rpm's. This leaves you with too much oil for 99.9% of your driving. Running a really small amount of 2 cycle oil shouldn't be a problem but it also isn't really necessary.
The best overall option is to install an adapter in between the engine and the omp that will let you pick up oil from an outside reservoir. This way you can run 2 cycle oil through the omp system and have it metered in the correct amounts. The engine oil also isn't circulated and now there is zero reason why you can't run synthetics. This is the best option.
Too much oil will hurt performance in the long run. If you still want to run premix with the factory system hooked up, use a higher ratio such as 600:1 or 800:1. Keep it low though.
10-06-2004 | 02:49 PM
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From: Houston
I just thought of an obvious way to get rid of the omp if you only want to run premix. Remove the oil metering lines completely and replace them with bolts. Leave the omp hooked up to the ecu though.
EDIT: This paragraph is wrong!!! I messed up!!!
"The oil metering pump is actually inappropriately named. It doesn't do any pumping at all. What it does do is open or close a valve that lets the oil enter the metering lines. The oil is sent through them using the oil pressure from the oil system. The pump doesn't pump anything."
The ecu just varies how much it is open based on rpm and load. If you disconnect the lines, the ecu doesn't know you did this. It would only know if the rotating valve stopped working altogether. Just another option for you to think about. The downside to this is that you can not forget even once to add oil to the gas when you refill. You also have to run more oil than the engine actually needs since you need to account for max loads and rpm's. Just something else to consider. If nothing else, you now know how the omp system works.
EDIT: This paragraph is wrong!!! I messed up!!!
"The oil metering pump is actually inappropriately named. It doesn't do any pumping at all. What it does do is open or close a valve that lets the oil enter the metering lines. The oil is sent through them using the oil pressure from the oil system. The pump doesn't pump anything."
The ecu just varies how much it is open based on rpm and load. If you disconnect the lines, the ecu doesn't know you did this. It would only know if the rotating valve stopped working altogether. Just another option for you to think about. The downside to this is that you can not forget even once to add oil to the gas when you refill. You also have to run more oil than the engine actually needs since you need to account for max loads and rpm's. Just something else to consider. If nothing else, you now know how the omp system works.
Last edited by rotarygod; 02-08-2005 at 04:49 PM.
10-06-2004 | 06:44 PM
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From: Florida
rotarygod: Thank you for the comments! You make some good points. I am planning to cut back on the mix at 2000 miles (end of my break-in cycle), to 320/1. I am also planning to go to an external injection oil reservoir when the warranty expires.
The external reservoir, marked in ounces, would also serve to inform the driver about the overall health of the oil metering, via observations on oil usage. Any suggestions on the reservoir pump necessary to make this conversion work?
As far as forgetting to add oil to the external reservoir, this is also true for any 2-stroke using oil injection, such as the Kawasaki Mach III I used to drive. Some owners (not myself) did fry the engines on these motorcycles, by forgetting to add injection oil. If the external reservior was a commmercial product, a low oil warning buzzer would be a necessity. I might be able to rig a warning buzzer up, as a backup safety device (I am an electronics engineer-hardware, in my day job).
The external reservoir, marked in ounces, would also serve to inform the driver about the overall health of the oil metering, via observations on oil usage. Any suggestions on the reservoir pump necessary to make this conversion work?
As far as forgetting to add oil to the external reservoir, this is also true for any 2-stroke using oil injection, such as the Kawasaki Mach III I used to drive. Some owners (not myself) did fry the engines on these motorcycles, by forgetting to add injection oil. If the external reservior was a commmercial product, a low oil warning buzzer would be a necessity. I might be able to rig a warning buzzer up, as a backup safety device (I am an electronics engineer-hardware, in my day job).
10-08-2004 | 01:52 PM
#11
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From: Des Moines, Iowa
2 Stroke Oil
ounces gals Ounces Ratio n/1
8 10 1280 160
6 10 1280 213
4 10 1280 320
3 10 1280 427
2 10 1280 640
8 13 1664 208
6 13 1664 277
4 13 1664 416
3 13 1664 555
2 13 1664 832
8 15.9 2035.2 254
6 15.9 2035.2 339
4 15.9 2035.2 509
3 15.9 2035.2 678
2 15.9 2035.2 1018
ounces gals Ounces Ratio n/1
8 10 1280 160
6 10 1280 213
4 10 1280 320
3 10 1280 427
2 10 1280 640
8 13 1664 208
6 13 1664 277
4 13 1664 416
3 13 1664 555
2 13 1664 832
8 15.9 2035.2 254
6 15.9 2035.2 339
4 15.9 2035.2 509
3 15.9 2035.2 678
2 15.9 2035.2 1018
02-08-2005 | 03:58 PM
#12
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From: Westchester NY
Currently using premix in my RX-8 fuel
I've had my 2004 for a 1 month now - picked her up with 6000K miles and have added 1K happy miles since 
As a new Rotary owner, I've spent a lot of time reading threads so that I can better understand the unique qualities of the Rotary. And with every day behind the wheel, I think that I'm getting a feel for my car and what she likes in regards to fuel, oil, warmups, etc
I found this older thread particularly interesting so I thought I post on it rather than start a new one.
So, based on Rotarygod's comments, I've decided to run premix with the factory system hooked up, adding just a small amount of premix to fuel.
I started experimenting with running TC-W3 2-stroke in my fuel in very small quantities: approx 800:1
Like OMCWankel, my use of premix is purely supplimental. I also hope to drive this car for many years and think it is beneficial to get some additional lubrication.
As others have mentioned, the Rotary really seems to like the premix. It idles more smoothly and seems to "whirrr" just a little bit more
Of course, it is subjective, but it does seem to me that this is true.
I also experimented with lower octane fuel as some said that the use of premix discounted the benefits of the higer octane fuel. However, I found the car definitely idled better with 93 and had less vibration through the shifter than it did with 89, so I went back to 93. I have yet to try 91 as it does not seem to be so common around here. Maybe I'll try a mix of 89/93
Anyway, so far, thumbs up for a little premix in the fuel.
As a new Rotary owner, I've spent a lot of time reading threads so that I can better understand the unique qualities of the Rotary. And with every day behind the wheel, I think that I'm getting a feel for my car and what she likes in regards to fuel, oil, warmups, etc
I found this older thread particularly interesting so I thought I post on it rather than start a new one.
So, based on Rotarygod's comments, I've decided to run premix with the factory system hooked up, adding just a small amount of premix to fuel.
I started experimenting with running TC-W3 2-stroke in my fuel in very small quantities: approx 800:1
Like OMCWankel, my use of premix is purely supplimental. I also hope to drive this car for many years and think it is beneficial to get some additional lubrication.
As others have mentioned, the Rotary really seems to like the premix. It idles more smoothly and seems to "whirrr" just a little bit more
Of course, it is subjective, but it does seem to me that this is true.I also experimented with lower octane fuel as some said that the use of premix discounted the benefits of the higer octane fuel. However, I found the car definitely idled better with 93 and had less vibration through the shifter than it did with 89, so I went back to 93. I have yet to try 91 as it does not seem to be so common around here. Maybe I'll try a mix of 89/93
Anyway, so far, thumbs up for a little premix in the fuel.
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MrRawrRawr (04-19-2018)
02-08-2005 | 04:47 PM
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From: Houston
I need to correct a statement I made earlier in the thread. The oil metering pump does in fact pump oil and not just use the oil pressure from the oil system. I had heard from a source who had taken one apart say that there was no pumping mechanism. This confused me since under boost, oil consumption would decrease and that wouldn't make sense. I have an OMP lying around so I disassembled it myself to see how it works. It does in fact take oil from the high and not low pressure side of the engine and it does pump it. There is a rotating screw type of pump that is connected to the eccentric shaft. The faster the engine spins, the faster it spins. The OMP is controlled by how much oil gets to this screw though and therefore controls how much gets injected. On the Renesis there are 2 "cams" that control oilflow. They are both different sizes. The smaller one is the primary one when the engine is at lower rpm's and at lower loads and the other kicks in the add to the flow at higher loads and rpms.
Sorry for the misinformation.
Sorry for the misinformation.
02-08-2005 | 07:21 PM
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From: SF Bay Area
Given the OMP is in fact a pump, wouldn't it be simple to cap off the oil feed line and route a new one from a standalone oil container?
________
LAMBORGHINI ISLERO
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LAMBORGHINI ISLERO
Last edited by PUR NRG; 05-01-2011 at 06:24 AM.
02-08-2005 | 07:59 PM
#16
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From: Houston
Originally Posted by PUR NRG
Given the OMP is in fact a pump, wouldn't it be simple to cap off the oil feed line and route a new one from a standalone oil container?
02-08-2005 | 08:27 PM
#17
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From: Dunedin, FL
For anyone who has seen old rotor housings, you can see the effect the oiling has by the difference in the patina between the center of the housing (past the oil hole) and the edge. This difference in wear can be significant enough, in my opinion to justify doing pre-mix.
Does anyone know how the Renesis gauges oil metering?
Can the OBD2 provide any data?
Does anyone know how the Renesis gauges oil metering?
Can the OBD2 provide any data?
08-07-2005 | 07:25 PM
#18
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From: Florida
I have an update to the original post. I have stopped using pre-mix, and have been using a product called Fuel Power for 3 months now. I have noticed the same fuel mileage as pre-mix, and the same freedom to rev. The car also starts easier, especially hot. This product is supposed to have lubricative and cleaning properties, and is less expensive than pre-mix, per application.
I will do a used oil analysis soon, and compare it to the previous analysis. Both will be posted on BITOG. The first post is at: http://theoildrop.server101.com/cgi/...c;f=3;t=002559
I will do a used oil analysis soon, and compare it to the previous analysis. Both will be posted on BITOG. The first post is at: http://theoildrop.server101.com/cgi/...c;f=3;t=002559
08-09-2005 | 05:47 PM
#20
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From: Florida
Originally Posted by bxb40
Where do you get Fuel Power from? Regular auto parts store? Cost?
It is called FP60 on the site.
08-09-2005 | 06:50 PM
#21
Originally Posted by PUR NRG
Given the OMP is in fact a pump, wouldn't it be simple to cap off the oil feed line and route a new one from a standalone oil container?
08-09-2005 | 09:13 PM
#24
Iso-egd......
I use a synthetic for clean burning, rated at least ISO-EGD or better. (the new EGD+ oils are out now.) The one I use is specifically for snow-mobiles, but the thing to look for is just the quality rating, ISO is a European system, Jaso/FC is the Japanese rating method.
I agree with Mr. OMCWankels' ratio of 160:1 or leaner, I use a 250ml measure that yields 200:1. Have used this since day-one, as soon as it came home from the dealer, and obviously with no ill effects. I have had the cat on and off lately for various reasons and it is in great shape.
Anyone fortunate enough to see inside a high mileage rotor housing would be struck by the difference the wear layer of oil from the stock pump makes, (in the limited area it reaches) inside the circumference. Still shiny as new in the oiled area.
Obviously I won't know if this makes the slightest difference to motor life overall until many years from now, but on the mileage front I get a consistent 23mpg to the Canadian gallon, 19+mpg US, and though mostly highway, I tend to drive on the "aggressive" side, and I get discount gas from the oil company I work for, so I don't really take it easy on the go pedal!
(I am not claiming that pre-mix is the cause of the good mileage, could be I just got one of the "better" ones!)
S
I agree with Mr. OMCWankels' ratio of 160:1 or leaner, I use a 250ml measure that yields 200:1. Have used this since day-one, as soon as it came home from the dealer, and obviously with no ill effects. I have had the cat on and off lately for various reasons and it is in great shape.
Anyone fortunate enough to see inside a high mileage rotor housing would be struck by the difference the wear layer of oil from the stock pump makes, (in the limited area it reaches) inside the circumference. Still shiny as new in the oiled area.
Obviously I won't know if this makes the slightest difference to motor life overall until many years from now, but on the mileage front I get a consistent 23mpg to the Canadian gallon, 19+mpg US, and though mostly highway, I tend to drive on the "aggressive" side, and I get discount gas from the oil company I work for, so I don't really take it easy on the go pedal!
(I am not claiming that pre-mix is the cause of the good mileage, could be I just got one of the "better" ones!)
S
08-10-2005 | 09:56 AM
#25
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From: Florida
Very good point, StealthTL!
I have used synthetic in the 2-strokes for years. Bel-Ray MC1 to start, and H1R now, mixed 40-50:1. When you open them up, wear is minimal, and some areas look like new. Very little carbon buildup in the ports.
Results like that made me a synthetic oil believer many years ago.
I have used synthetic in the 2-strokes for years. Bel-Ray MC1 to start, and H1R now, mixed 40-50:1. When you open them up, wear is minimal, and some areas look like new. Very little carbon buildup in the ports.
Results like that made me a synthetic oil believer many years ago.