RX8.PIPE.DREAMS

iTrader: (1)

If people are curious, thanks to the contribution of members, we are finally painting a picture of some people who have very high mileage on original s1 engines. These are people that are on the original, original engine and never replaced it. But guess what? A great deal of them did not premix to get to those high mileage figures. Check it out:

https://www.rx8club.com/rx-8-discussion-3/highest-mileage-2004-original-original-engine-165164/page6/

Of course I am a premix'er but there is a trend that is suggesting something about not premixing...
You can also check out the previous pages but that was before I suggested having a questionnaire to converge data points with engine life.

olddragger

iTrader: (3)

i am still wondering about this.
If premix is a holy grail of the rotary engine why are so many getting high milage without doing it?
After talking and doing a little research--it seems the 09's 3nd "injector" is to change the distribution of the lube --not to increase it.

Also rotaries are not 2 cycle engine---the only way premix can offer any lubrication, first it has to get rid of the gas--combustion cycle. That leaves some oil--right. Well that oil goes right out the exhaust (immediatly after combustion in our engines) and is not resupplied until after the next combustion cycle. So its lubricating only between combustion and exhaust? Now if the ratio is changed --say 1.5 oz per gallon--then some is left over?
Also we run rich--especially cold start and town driving. Rich mixtures cools the combustion chamber and that also promotes incomplete combustion. Incomplete combustion can increase the pre mix oil deposits and add to a already known problem?

Over time I will bet you that premix (and gas too) influences the spray pattern of our injectors and make them less likely to spray properly. This also influences getting an incomplete combustion and having left over products that remain in the chamber.

if you have gas that is premixed in your tank and go away for a week---is that gas still as good? I know on motorbikes its not.

Like i say some folks know a lot more than me--but i am having conflicts in continuing premix.
Now for Track---yes premix. For DD I am not so sure.
OD

RX8.PIPE.DREAMS

iTrader: (1)

Well Olddragger, I definitely don't know enough about what goes on in the rotary combustion cycle to confirm/refute what you said. I do know Idemitsu makes the claim about rotary engines:

9krpmrx8

iTrader: (46)

Marketing BS IMO. Idemitsu is not certified which means they didn't wann buck out for the testing required to meet those standards. We have been over this before, if you look at product data sheets Idemitsu is pretty good but not the best. A good certified JASO 2 stroke is what I use. ut I don't believe idemitsu premix is bad either, it's good stuff, I just think it was marketing ploy to make it rotary specific.

But OD, I have been contemplating this as well after looking at my fuel pump sock. I believe 100% in my SOHN because good 2 stroke has to be better than dirty engine oil but I'm not so sure any real lubrication of my APEX seals is happening from premixing my gas

BigJeff

After reading some of the messages here I decided to start premixing. I'm using 400:1 for no particular reason other than that small a quantity of 2-cycle oil can't possibly do much harm. I'm on my first tank. So far so good and it seems a bit smoother at idle, but is there any reliable data on the proper mix to achieve the desired lubrication benefit without damaging other components like pumps, converters, injectors, etc.?

I'm enjoying my first RX-8...a silver 2004 GT 6-speed with 18,000 miles.

olddragger

iTrader: (3)

I think I have convinced myself to not premix for dd--especially in such low concentrations as a lot do?
My reasons:
1- I dont think we are getting lubrication from premix in the area we think we need. The middle of the apex seal is showing wear on premix engines and non premix engines. Non premix engines are getting high milage--look at the the +100,000mile engine thread. Apex seal wear is showing in both premixed engines and non premixed engines.
I am thinking center apex wear has more to do with the hotspot sparkplug area than currently believed.

2- i dont believe marketing -- I have never seen honest marketing by a big company. Small company's like Mazmart etc ---yes.

3- Pre mix will affect injectors over time---dont believe me--take some injectors off and send them in for analysis. Gas affects them too--but premix cant help

4- premixed gas is not stable in the tank for long periods. So if you park your car for a wk or too--the gas is not as good.

5- Incomplete combustion with premixed gas leaves even more deposits.

6- The oil in the premix is not available until after the combustion has taken placed, but the exhaust is immediatly afterward --so most if not all of whatever oil there is goes out the exhaust port? Remember the premix oil is NOT on the rotary face --it is in the air of the combustion chamber 1st. True the combustion probably pushes the oil to the rotor face and that part of the housing but it cant stay there long. This is why out oil "injectors" do not inject--they weep so the apex seal can distribute it across the surface.

Totally agree 9K--sohn is good.

Now for track events----hell yea---at least 1 oz per gallon. Anything less is cat ****.

9krpmrx8

iTrader: (46)

Okay OD, after reviewing some animations, maybe there is some lubrication happening when the mixed fuel is injected but how much is the question.
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olddragger

iTrader: (3)

cant view that right now---at work and its blocked.
Will review tonight.
Now I know there are cars out there (older models) that have removed their omp's altogether.
But they mix at a much higher concentration. So I am not referencing them. Higher concentrations will leave left over oil.
OD

Nubo

My understanding is that the combustion shockwave (or maybe just the act of compression?) causes some of the oil to condense into fine droplets and precipitate on the metal surfaces. I've looked around the internet trying to find some description of that mechanism but haven't really found anything. So I may be way off base.

9krpmrx8

iTrader: (46)

Yeah, from what I can see there has never really been any scientific testing of premix on our engines.

GeorgeH

iTrader: (2)

Of course, pre-mix oil is only introduced when the fuel is injected.

The question is, does it persist somehow through & after the combustion process?

My understanding is that this is where the additives matter. ZDDP, or whatever. These additives bond to the metal and, even in the complete absence of the oil, will sacrifice themselves & protect the steel, at least for a short period of time. So the objective should be (if I have this right) to ensure enough of the additives get on the seals & housing to protect the engine through all four cycles. Make sense?

This is where we get into conversations about oil A vs. oil B, and basestocks, etc. For example, I’ve read that poly ester base stocks (like those used by Redline) have a natural affinity for metal. Then there are high ZDDP oils like Valvoline Racing oil. Then you have Royal Purple making their own claims (which is what originally drew me to RP). Finally, you can talk about the relative importance of ensuring that both your crank case oil & pre-mix use compatible additives, so that they don’t compete with one another on the surface of the metal. Which could lead one to conclude (rightly or wrongly) that it is critical to use oil from the same manufacturer in your crankcase & gas tank.

So, what is the right answer? I’ve not a clue, but I am going to continue premixing, even on the street. For now, Rotella in the crankcase & Idemitsu in the fuel tank.

I suspect the number of people in the world that know the answer from a scientific/engineering standpoint is very small.

ArXate

I'm one of the handful of 150,000+ owners on this forum, and like Pipe Dreams, I've also noticed most if not all of these super-high mileage RX8's were never on premix. But before we can make more definitive inferences on a causal relationship between longevity and no premix, I think we need to consider 2 other factors.

The first factor is a reasonably common sense direct connection between amount of fwy cruising (driving style) and the year the RX8 was first made. In other words, very very few of the mid-2003 owners will have had a chance to approach even 100,000 miles (7 years X 15,000 mi/yr). I believe most sports car drivers drive those cars at a rate much below 15,000 mi/yr. Accordingly, pretty much only drivers who drive a LOT would even get to 150,000 miles over 6.5 to 7 years; and of course those who drive a LOT tend to be fwy cruising. Given the TIME situation, we need to wait several more years for more people to approach 150,000 to 200,000 miles. Once the sample of ultra-high mileage RX8's increases, I wonder what percentage of those cars were primarily CITY driven.

The second factor focuses on the drivers who do primarily fwy cruising who also premix. Are these drivers just not getting to 150,000 miles because their engines are breaking down much earlier OR are we just not hearing from them? Conversely, I wonder what percentage of the drivers on this forum whose engines have broken down early are fwy cruisers?

The connection point between the 2 factors discussed above is fwy cruising. I think a very small percentage of RX8 owners would do mostly fwy cruising. I'd like to hear more from these "fwy-cruising" owners. I'd like to know what percentage of these "fwy-cruising" owners use vs. do not use premix. And what percentage of these "fwy-cruising" owners are getting to 150,000 miles WITH PREMIX vs. WITHOUT PREMIX.

Nubo

^^ I'd agree that high-mileage renesis at this point would likely be freeway cruisers. But I imagine the 150,000-mile club is pretty small. The percentage of drivers who premix is probably also small. So not sure if the sample size is big enough to draw any conclusions.

robrecht

Interesting, OD. Regarding the apex seal wear in engines that used premix, was the wear bad as in engines that never used premix? Did the premix engines use premix from the start or only after 5k, 10k, or 15k miles, etc? Finally, how many engines are you talking about? A couple, more, less?

You really need large sample sizes to speak about potential benefits of premix. If 25% of engines have failed, that means 75% have not. Looking at a few engines doesn't mean much. That's not an argument for premix, of course, but keep in mind how many older rotaries have abandoned their OMPs and exclusively used premix, I think typically in a 1/2oz per gallon ratio.

ganseg

iTrader: (5)

Congrats on your new car! I recently bought a 2005 with 19K so we are in similar circumstances. I premix with 1/2 oz per gal and use Amsoil Saber Professional. I will double that for my two track events this year.

The idle on this car was good before I started, so I didn't observe any change. On my 2004, which I bought with 30K, my idle got smoother but then got rougher again. I changed my plugs and it got smoother again.

Do you know the history of your car? If you can find out how old the plugs are, and if the software was upgraded will be helpful. The later would be on the Mazda Warranty History from any dealer. The former may only be on the individual dealer's record - like if the car had been flooded and got new plugs (I think they only replace the two leading plugs.) Plugs on RX-8's look like crap within several hundred miles!

Chad D.

iTrader: (19)

That is also my formula, with Amsol Saber Pro, Idemitsu or my personal favorite Legend zx-2sr.
I have two other wankel engines that are 2cy, and I am a stong believer in the efficiency of quality oils (race oil works better) and every tenth tank I will do a "cleaner" mix with an injector cleaner.
I would say it is a bit premature to nay-say premixing.
My uncle has premixed his rx-3 and Norton ever since new and they still work great, his rx-7 he didn't premix is dead. Not scientific, but neither are the high mileage claims either. I believe rotary engines need (even a little) oil to be there and any case of a dry spot at 8k rpm is trouble.
I own an 04 and premixing is how it's done.

RX8.PIPE.DREAMS

iTrader: (1)

If you guys mix 1/2oz to a gal, how much do you use for a typical tank of gas?

9krpmrx8

iTrader: (46)

Are you serious?

Chad D.

iTrader: (19)

0.01478676484375 Liters of oil to every US Gallon
0.10350735390625 Liters when I'm @ the petrol dispensing mashine

or 3.5 oz's

ganseg

iTrader: (5)

The only part I am on the fence with now is the cleaner. I stopped mixing it with the premix under the theory that it will somewhat counteract the premix. I did think of doing what you are and running straight cleaner at some interval (I was thinking every 3 months but now may go shorter.) I have the FP Plus.

olddragger

iTrader: (3)

saw the animations today 9K and its easy to see where the premix can come into play. Since the oil in the premix is not available until the gas has been burnt off--its not very long after the flame front that the exhaust is open--not for long at all.
There will never be proof if premixing will work or not.
At anything least than 1/2 oz a gallon ---i strongly feel its not doing anything.
If it does we get into things like -do we use air cooled/water cooled type, synthetic/conventional--matching additive packages etc, etc
OD

Chad D.

iTrader: (19)

Ganseg - I buy a set amount of premix, use it all up, use the combustions chamber cleaner, and usually change up the brand of 2cy. I have three brands I use, I've always done it that way ever since I've been thirteen with my snowmobile, when I was 22 with my fd and just keep doing it with the 8. My car has 65k and runs awesome, I could use some new coils soon but considering I'm only on the second set of sparkplugs too, the premix hasn't been fouling up all my ignition bits.
I've never really thought of mixing premix and cleaner. I wouldn't do that. maybe if I had some cheapo 2cy.

invasion08

iTrader: (7)

While undertaking development work on the RX-8 Renesis engine for SCCA T2/T3 use, we decided to introduce extra oil into the fuel to monitor the effect. To our surprise, this additional oil increased power! Further dyno testing found that by adding 10 oz. of Royal Purple 2-Stroke Oil to 6 gallons of fuel, we gained an average of 1.7 HP from 2000-9000 RPM, along with an increase in peak power of 4 HP. We validated this increase by changing back to a “non-oiled” fuel - and the power returned to the previous level. Later, we tried the same test with another brand of synthetic oil with nearly the same results.

For racing applications, the addition of a high quality synthetic oil increases power and most certainly decreases wear. The only negatives are the cost of the oil and an increase in the tendency to foul the spark plugs. (Note: We have not performed these tests on non-RX-8 engines yet, these results are unknown.)

Copyright 2007 Racing Beat, Inc ©

Chad D.

iTrader: (19)

Nice of you to add that.

Vlaze

iTrader: (14)

That's great info thanks. However for SCCA or other racing the engine is running a lot harder through RPMs and generally burns off a lot of carbon without building up as much contrast to a typical DD. The typical DD scenario is what most of us have to address and find ways into reducing the failures that can or do occur. Using 10 oz for 6 gals IMO would be excessive for a DD and would just make matters worst I believe with oil that would never get burned off.