Hello

Bought my 04 rx8 awile back and read alot in this forum.

Used premium gas, 5w20 oil ever since (conventional). Seen threads saying to replace coils/plugs, but have not read any justification to do this for this car yet. 56 miles on it. Car was originally thought to have alotta power, but like any car anyone owns, loosing power is a matter of perspective after awile, although I could be wrong. Oil pan always contained moisture.

couple questions;

Do all these cars have lifetime metal air filters? could not replacing this type of filter affect engine contamination/ oil cleanliness over a certain span?

How can the engine lose compression? passing through seals? air/fuel intake mixture? catalitic sensors? coils/plugs or miss firing thing?

Not looking to abuse this car as I dont think its a heavy horsepower sports car.

thoughts?

Car runs better in colder air intake, (possibly like any car I guess).

Read about boat motor oil addition to the gas to help performance or compression? Is this healthy to the original design?

 

Conventional paper air filter. Changing it is a bitch until you know the secret...I think there's a DIY on that.

They lose compression from seals (either apex or side) failing. Lots of discussion here on why, mostly centering on not driving the car hard enough. If yours seems to have lost some pep, find a good dealer and get a compression test.

Adding oil to the gas is called pre-mix. There are a lot of very good threads on it, including a sticky. Well worth looking up and reading.

Ken

 

driving hard will kill the engine which I read about

 

Then you read wrong.

 

Long periods of stop and go city driving in very hot climates will kill the engine if you don't have the latest re-flash ordered by recall several years ago. Hard high rev driving is good because the rx8 has a high rpm rotary engine and needs it to reduce carbon buildup. Pre-mix is unnecessary if you run 87 octane regular.

 

On the oil go thicker, read threads on it. Personally I think it's a crime to put 5/20 in these cars and Mazda needs to suck it up and put 5/30 in Series II. Admit it Mazda you made the wrong call 5/20 is weak sauce. How many more engines have to be replaced? Anyway.. It's lot more going on than just the oil but there is a set of flaws with Series 1 engines that seem to give them 40-70,000 mile lifespan. Many threads on it.

As far as the horsepower / muscle issue. Drive it like you stole it lol.

Dude I can take a bone stock 1st gen RX7 with 100hp and score kills in good non drag road race. 1/4 mile is not everything. Good driver can tear some excrement up in just about any ride. This car does the Top Gear track same as Nissan 350z and BMW M3. A loaded M3 is over $60,000 bucks. This is driven by Michael Schumacher.

 

Engine replacement on series 1 engines are a small percentage. Probably caused by improper oil lubrication and overheating in earlier models before the correct flash came out(shame on Mazda for rushing to market). Series 2 has an extra oil injector so it's even more unlikely to happen. There are many high mileage 04's with original engines still going strong. Mine has 43k and runs like new. We'll see. As a side note I took my 8 to the tail of the dragon in NC. Only thing that could keep up to me were expert sportbike riders and a honda S2000. My car is stock and it rocks.

 

Where specifically did you read that?

Ken

 

Paper air filters, and the OEM air filters are so good, that even Speedsource still uses them. An alternative is the K+N filter, but if you live in in area with any sand at all it isn't recommended. Speedsource had K+N filters at Daytona until they lost 3 engines from sand ingestion, went to paper filters, saw a 1HP drop, but eliminated the sand problem. No reason to use something else.

Generally it is through wear on the apex seals and/or the housings, making grooves or other uneven wear that will no longer seal completely. Once it loses a complete seal, it beings to wear faster and faster, as the blowby accelerates wear. The cause of the wear in the first place is usually lack of lubrication, which is a 2-fold issue between lack of proper injection of oil, in series 1 engines this occurs most in the middle as it only has 2 injectors pointing towards the outter edges. The other issue seen is main bearing wear, which creates an unbalanced rotor movement, which excessively compresses seals in one direction, and doesn't compress the seals enough in the other direction. Excessive heat is also an issue, as it breaks down the oil too fast to be of good use.

Abuse for a rotary isn't the same thing as abuse for a piston engine. Keep it cool, keep it lubricated, and rev it high under load on a regular basis to keep carbon clear. ***** foot it around constantly and you will end up with more issues. Ignore those issues, and they will continue to grow and spread to other areas of the car.


Butt Dyno there. The OEM intake is VERY good, with maybe a couple HP gain for the AEM/Mazdaspeed intakes, no change or even power loss with other brands.

Not 'boat motor oil', but 2-stroke oil. Basically premixing 2-stroke oil helps assist in lubrication of the seals inside the combustion chamber. 2-stroke, rather than conventional 4-stroke, as 2-stroke is designed to be burned. There are various brands that people go for, but dont just grab any old 2 -stroke. Do your homework.

You read wrong. Flogging a piston engine is deadly, flogging a rotary just makes it smile in pleasure.

Um. WTF is this? Completely bad information.
87 octane is simply the resistance to detonation. A perfect engine should run 93 octane to avoid knocking/detonation, though as you lose compression, backing down to other octanes is fine, as your compression loss reduces the heat from compression, and your risk of detonation.
The octane has nothing to do with lubrication, which is the purpose of the premix.

The actual percentage is not known, Mazda won't release it, but it was highest on 2004 Automatics, 2004s in general as a year, with the % dropping farther and farther for later model years. Part of the problem was also the reman facility not building engines to proper specs for a while, hence several people with multiple changes. And the causes of the failures are well documented, see my notes above.

 

Um. WTF is this? Completely bad information.
87 octane is simply the resistance to detonation. A perfect engine should run 93 octane to avoid knocking/detonation, though as you lose compression, backing down to other octanes is fine, as your compression loss reduces the heat from compression, and your risk of detonation.
The octane has nothing to do with lubrication, which is the purpose of the premix



by your own statement, lower compression makes less heat and lower octane is fine. Why premix under these conditions? The extra lub of premix works best with hotter high octane engines to keep a more even temp. You need to reason it out. Most guys who premix use premium fuels for optimal performance. I think I'm right. My car has never detonated on 87 regular. I don't need premix. Sorry.

 

Let me back up a few steps.....where are you getting that premix helps avoid or helps cause detonation (it's hard to see which way you are trying to say it)


Premix is an OIL added t gas for lubrication. While yes, it does change the octane rating, it does so only faintly. Premix is for lubrication of the Apex seals, and has nothing to do with detonation, preventing it or causing it.


87 vs 93 has nothing to do with lubrication.

There are 2 completely different things here that you are getting crossed.

 

I guess what I'm saying is, if you can run lower octane from new without detonation, you will lose a little performance but gain engine longevity with or without premix simply because your at a little lower compression and heat level. Does that make sense?

 

ISPY! I NEED HELP WITH THIS GUY!
Actually, it just shows that you still have mis-information

Lower octane doesn't equate to anything but a lower resistance to detonation, which means you need a hotter spark/surface/etc... to ignite the fuel. A spark plug can provide this heat for the entire octane range.

Using 87 vs 89 vs 93 vs 94 vs 101 etc... has nothing substantial to do with how much heat the engine is generating. In a minor minor way it does, in that there is faintly more power available from lower octanes, as it burns easier and more readily. Higher octanes provide a slight increase in the resistance to detonation, which means a higher heat is needed to ignite it. Same energy content though.

BUT!

It doesn't matter if you had the rotors cold and were just using another machine to sweep them around and around, they still need lubrication. The OEM OMP injects oil, but not enough, and not in the center. premixing oil into the gas tank helps to provide this extra lubrication, especially for the center of the apex seal. I don't care what the heat in the engine is like.

There is still a violent combustion of flammable liquids in a gaseous form, and that heat burns away oil, both the injected 4-stroke and the premix-ed 2-stroke.

Compression is only related to seal clearances, and if they are properly mating to the surfaces as they sweep around. Well, the rotors themselves are attempting to compress the air/fuel mix, and the seals prevent it from escaping, forcing the compression. If the seals wear down, then the rotor can't compress because the mixture is escaping into the next chamber or the last one. In extreme cases, the side seals can be the leak as well. Lower compression does in the end mean lower heat, I will agree with you there, as you aren't getting a full burn, and are wasting the extra gas instead of generating heat from it.

But lower heat doesn't mean less wear... Higher heat does mean more wear when the heat is over the critical point for the oil that isn't supposed to be burning, but under that point, not so much.

 

Mazda says the recall fixed that apex seal lub problem on early models by injecting more oil. So, premix is no longer needed or is it? Does the manual say premix is needed? Did they lie? Why does my 8 run so well on regular with no detonation. 43k miles on regular and it runs great. You have good info and understanding but it appears to b a yes and no situation. Are you sure premium fuels do not generate more heat in combustion therefore requiring more lub(premix) to cool the seals? Somehow seems it does. This is interesting to me.

 

1: The 'recall' to MSP16 injected more oil, but it simply can't fix the problem that there is still not middle injector. The series 2 renesis fixed that, but can't go retroactive on that fix

2: The manual doesn't state premix, simply because they would hardly sell any if there was a hint of needing to add premix. Ideally, Mazda should have supplied a 2nd oil tank for 2 stroke that can last 5-10k miles, and adds it to the fuel stream automatically. Refill on normal service intervals. But the manual also says 5w20, which has been proven to not be thick enough. If you accept that MAzda got the initial ECU tune and oil injection wrong, then you have to accept that they are not perfect in every way. If they were wrong there, they can still be wrong elsewhere. Insufficient lubrication and limited cooling is what kills rotaries, and over the years, each successive rotary has been less lubrication and less cooling and more power, and has ended up with lower reliability as a result. The FD was the worst because they added FI on top of those problems. The series 2 renesis finally reversed this trend with the re-increased oil pressure and 3rd oil injector, but realistically, it still isn't back to where it should be.

3: 93 is only recommended, but certainly not required. You aren't the only person to run perfectly fine on 87. Part of that has to do with your colder climate. Even in summer, you simply don't reach the ambient air temps that socal, AZ, and FL do. With lower ambient temps, your cooling system can shed heat faster, which translates into a cooler block, which reduces the likelyhood of detonation. It is also ECU related. Some Renesis ECUs hate anything less than 93, some love it. Every engine has it's own traits. Just because you can, doesn't mean every rotary engine is the same.

4: Yes, I am sure that 1 gallon of 87 has the same energy content of 1 gallon of 93. 93 simply allows for a higher compression to extract more power, if tuned to do so.

5: Lubrication doesn't cool the seals at all.

 

This is informative. One last question. When the ecu adjusts timing, air fuel etc for detonation on regular fuel, does the compression stay the same, or do you lose some? I had my compression checked on recall and it was in the accepted range.

Thanks

 

The 2 primary things generating compression is the force of the spinning rotor, squeezing the air/fuel mixture between it and the side of the housing.

Exhibit A: (poor image of the process)


Exhibit B: Better look at the rotor itself. See the indent along the face of the rotor? That is where the majority of air/fuel mixture is at maximum compression. The seals along the tips and side hold it in.


The only thing that can change compression is the shape of the rotor, shape of the housing, or condition of the seals. The ECU can not adjust any of these aspects, and Compression is entirely mechanical. If you do not have a perfect seal, then speed of the rotor can change compression, basically if the rotor is moving fast enough then the air/fuel mixture doesn't have as much time to escape. This is why low RPM power loss is generally more significant on low compression engines than high RPM power loss.

 

Thanks all for the info

What is the recommended rpm to shift for this car? 4000 rpm? I do rev it up higher all the time, but shifting at 4000 is normal city/traffic driving. Also, I red line say once a week. Is this considered baby'ing this car?

Also, I know its 2 stroke oil, but just called it boat oil because of the two stroke boat motors that require mixing. recommended brand if I try this?

 

Idemitsu.

 

That should be fine. Occasional rev'ing is all that is needed to help keep the carbon clear. Granted, since giving it a good Wankle Spanking is tremendous fun, I usually redline 4-10 times a day. I don't hold it there, too much heat buildup in the transmission and oil, but I do get wide open throttle (WOT) to redline quite a bit, and cruise at 4,000.

With my wife in the car, I shift around 5k.


This is your best bet.

 

The synthetic blend premix is shown on their website. synthetic is not recommended by Mazda, but this is offered?

 

Synthetic vs non-synthetic is a choice you have to make. Mazda doesn't "recommend it", but they have never said that it is prohibited. Only that they haven't tested it, so they can't speak to it's benefit or penalty, so they don't recommend it.



Though there is a difference in meaning depending on where you put the accent.

Negative "Not recommended" meaning "We recommend that you do not use it"
vs
Neutral "Not recommended" meaning "There are other types we do recommend, but this is not something we can put in that list, though we don't see a reason to say no either."


One is stating a negative, the other is simply not able to provide a positive, allowing for a neutral statement.


This is the hinging point on much of the "to synthetic or not synthetic" debate out there.

 

Well, this was good info and I can conclude I get away using regular 87 octane and no premix because I live in a cold climate where summers seldom exceed 85 degrees and if so only a short period of days. I don't have the heat issues like in hot climates. You guys buying used try to find an 8 from the cold climate region. the engines will have been less stressed by heat.

 

Curious as to what you use based on your personal experience?

 

That's just one of the points. There are more...which is what makes the debate so entertaining and unending.

Ken