Nubo

It seems to me that this carbon may have always been there, but with peripheral ports, simply got slung through the exhaust port. Combustion of the oil can't be an instantaneous process, otherwise we'd be in a big heap of trouble. So it seems reasonable to imagine that the injected oil exists at all times as a mixture, ranging from fresh oil, to ash -- and there are countless hydrocarbon possibilities in-between from "oily" to "tarry" to "sticky" to "flakey". With perhipheral ports, the median "age" of this goo was probably a lot less than that which exists in Renesis. Meaning, more "carbon" problems for Renesis, and a tendency towards the stickier and flakier compounds since the oil has more time to "cook", and is being replaced by fresh oil at a slower rate.

rotarygod

I agree that carbon could get out of the peripheral exhaust ports easier. I do think that the fact the oil injectors point sideways to get more oil to where it can't burn only further adds to the carbon buildup issue. It creates more of it and less can get out.

zoom44

make that 100%. they have people whose job it is to watch the forums. at one point over 20.

robrecht

My Dad used to design Diesel engines and he would quote an old maxim: "Perfect is the enemy of good enough."

olddragger

iTrader: (3)

All car manufacturers have a "whoops" or 2 in their histories. Growing pains. Thats all.
olddragger

Nemesis8

iTrader: (3)

It's a remarkable engine still, remember that it won an International Award. (I think the new 16 will be even better.) It's still affordable to rebuild or replace due to it's simplicity. I'm going to extract countless miles out of the wonderful chassis it sits in.

california style

with the fuel pump / filter assembly, how can you check it? (without external gauges etc)

Also can you "clean it" or does it need replacing if its clogged up?

As someone said, if you are going FI, its wise to know how much fuel you can flow!

DrRockin99

Well, finding this tread was very timely for me, since I have just left my car at the dealership for a engine swap. Went in with check engine light on to find out what was wrong. Just hit 29,000 miles. So my question to you all is, with the new motor should I premix to prevent this from happening again?

musclecarconvrt

Better safe than sorry. 2-3oz per tank would be plenty if the stock OMP is operating as well.

Having an engine go bad at only 29k really stinks. The new one should be fine. Try not to get too scared. Mine has 87k on it and I only pre-mixed for about one month durring the hottest part of last summer for extra protection. Exop1's engine had over 110k on it when he volunteered it for Mazmart to tear down. looked like his engine though worn had a good bit of life left in it.

New Yorker

I'm of the opinion that if...

- your car is completely unmodded
- your car has the latest ECU flash
- your car is not raced/autocrossed
- you check oil level every other fill-up and don't let it drop more than half a quart or so
- you use 5W-20 non-synthetic
- you let engine warm up a minute or two
- you don't rev above 3K rpm or so until engine is fully warm
- you rev it to redline and run in the higher rpms (5 - 8K) now & then

...you shouldn't have to premix. (In fact, I'd be curious to know what percentage of people who had engine trouble did not follow all these rules.)

Anyway that's just my hunch; I could be wrong, but that's what I'm doin', so time will tell...

rotarygod

I'm of the opinion that everyone with a Renesis, regardless of how good their maintenence is, needs to premix unless they find a way to add a 3rd oil injector. I also consider a good synthetic that is thicker than 5W20 to be mandatory for max engine life.

DrRockin99

New Yorker, I did everything you posted before this happened, I was driving to Dallas from Amarillo when half way there the engine light came on. Even on the way to the dealership the check engine light went off. I almost turned around and not go, but thought I better get it checked. But I had noticed when getting above 5500 rpms, it didn't have the power, but I thought it was because I installed the ramair duct from Racing beat, it hadn't ran right in the upper rpms since I put that on. I was going to take it off to see if that made any difference. I babied my car 99.9% of the time. New to this premix thing, but they did tell me the Apex seals were breaking. Might really have to think about doing it. Sure don't want to change engines again, thank God for warranties!

New Yorker

Except you didn't follow everything; the first thing I mentioned was "if your car is completely unmodded".

Again, I'm no expert, not saying I'm right, but my hunch - just my hunch, mind you - is that the vast majority of 8s with engine problems are in one or more of these groups:

- '04, first-year of production w/teething problems
- Car does not have newer ECU flashes
- Modded in some way
- Oil level not checked regularly, or not kept within half a quart (or so) of full
- Cold engine not warmed up at all before driving
- Engine revved high before fully warm
- Engine never revved high; never redlined
- Not using 5W20, or not using conventional oil (I doubt that's critical, though; 5W-30 or synth prob fine)
- Premixing

That said, good luck, DrRockin!

alnielsen

iTrader: (4)

RG,
Because of this and other threads that have come up recently here, I have been premixing for the last 3 tanks of fuel. I haven't felt any power increase because of this, but what I did find was an immediate change in the exhaust note. The sound of went to a lower tone and maybe a little louder.
BTW, this is engine #3 and it has about 12K miles on it.

nycgps

iTrader: (1)

My suggestion is :

Use at least 5w-30, if ur area never snow, use 10w30 or even 5w40 or 10w40.

I saw a lot of Rotary engine pics online (probably couple hundreds), and if u did look at expo's motor, if the OMP if its really *good enough for stock car*, that kind of wear on the apex seal wouldnt even exist. but you dont have to premix like crazy since its going to foul ur plugs, 4oz per tank is probably what you want for streets. If u're going to track, 8oz sounds good.

since I never believe in 5w20, I've been premixing for quite some time, never had a problem, and I've been using 5w30 since 5K miles or so.

Also I use nothing but *Full Synthetic*. Have been using Royal Purple for a long time. Lately I got some Syntec for a pretty good price /w Mobil1 Filter, but most of the Syntec are not *true* Synthetic, only the 0w30 is a Real Full Synthetic oil, the rest are Hydrocracked Group III oil -____- .

Im going to use the Real Synthetic on my car(0w30), and leave the rest to my father's CX-7 and Brother's SE-R. Not gonna be long b4 they're all gone

Brettus

iTrader: (2)

did you read this thread ? I don't think you could have to come out with that ....

nycgps

iTrader: (1)

The wear is down to the copper area ... and yes Expo was using 5w20 the whole time b4 60K I think. then he switched to 5w30, and maybe 10 K later he start premixing.

SpIcEz

nycgps

About the 0w30, your talking about the Castrol Syntec right ?

Are you going to run that all year round or just in the winter times ?

nycgps

iTrader: (1)

Im gonna run it until I run out of supply.

Then Im going Redline all the way. Group V BABY ! and I will get 5w40.

It's fine for all year use btw

SpIcEz

Thanks, now here's another question

I saw allot of... Mobil 1 isnt that great threads.

I dont think its the end all, and Im a supporter of RP, but I get points from Esso up here in canada, and more than enough to get free Mobil 1 oil from my points, which I can pick up at the gaz station off the shelf.

I used it all the time in my Sentra's SR20DE.

For the fact that I get it free. Any thing wrong with using Mobil 1, like 5w30 or any other Mobil 1 suggestions ?

p.s. Kind of an advantage in this case having to gas up so often with the RX8 Esso points FTW ?!?!

New Yorker

Of course I read it. I just don't happen to buy the assumptions the OP makes. The title of this thread, "Renesis engine issues finally identified?" ends in a question mark, promising a healthy discussion about what the "Renesis engine issues" might be. Yet curiously, from the very first post, one quickly realizes that, in the mind of the OP, there is, in fact, no question at all.

The OP has determined that 1) the "issue," common to all Renesis engines, is that certain parts are not sufficiently lubricated, leading to premature wear and shortened engine life, and 2) that this lack of sufficient lubrication is a function of the current design. He points to Mazda's upcoming changes to the Renesis as "proof" of this. Like many here, he also believes premixing is a way to help alleviate the "problem" that he believes is common to all current Renesis engines.

But there is another way to interpret the facts, which I find more plausible. And my interpretation of the facts is consistent with the more-or-less "average" reliability ratings the 8 has achieved in various long-term road tests and in Consumer Reports. (And all seemingly without premix, somehow. Which, by the way, Idemitsu does not recommend for non-raced, bone stock cars):

1) The current Renesis is, in fact, not a "flawed design". Unmodded, unraced, and properly maintained, it's as reliable as other engines, if not more so. Without premixing.

2) Early '04, first-year-of-production engines suffered as a result of not-yet-perfected ECU settings, ultimately resolved.

3) The only "issue" with the Renesis is that, unlike ordinary engines, it's not very forgiving of owner neglect, engine mods, using the wrong oil, etc. So it's very fussy… and operates with a relatively small margin of error. I strongly suspect the vast majority of engines that have had problems are either a) first-year-of-production '04s operated for a time with not-yet-perfected ECU settings, b) modded in some way, or c) neglected or abused (i.e. oil level not regularly checked, oil level not kept high enough, wrong oil used, engine not warmed up before driving, engine never revved high or redlined, etc.)

4) I suspect Mazda is changing the Renesis to increase that small margin of error. It'll make a very good, and reliable, engine... better. And even more reliable.

nycgps

iTrader: (1)

More like Mazda *under estimate* the real world situation. and the *poor ability* of 5w20 oil.

Sure Mazda will test stuff b4 they use them, but remember sometimes it can take years before a problem will show. Some might say *oh, thats not a problem then*. Well, if its a problem, then its a problem, no matter after how many years b4 it shown.

Agreed somewhat, but Ultimately resolved? I dont think so.

Mazda knows what is going on with the engine, especially the Apex seal part, I mean we can see it, Im sure they see alot of them, their solution is to increase the injection amount and hope that the engine can last a bit longer. You know when the car is up to certain age, say, over 100K miles. People might think oh its normal for engine to break down, its already a 100K miles car ! But in fact, if you premix it or start with 5w30 in the first place, your engine might be able to last over 150 even 200K miles. But they will not know, cuz their engine blew at 100K already and they think its *normal* and no further investigation follows.

Cant say about abuse, but you cant really blame it on modded in someway, Even stock cars breaks down, Remember what happened to the Rx-7 ? Even bone stock cars overheated like there was no tomorrow.

Im not saying rx8 has as much problems as RX-7, but have u ever thought that this can happen to the Rx-8 also ?

People actually made their Rx-7's life *longer* by giving it aftermarket Radiators, better oil coolers, bigger body kit, etc.

Some Aftermarket parts do suck, but you cant blame it on that.

and if stock is the best, no aftermarket parts will exist. some are crappy I know, but most are the same or better than stock.

At least they know what went wrong. if they kept it like that b4 Im sure Renesis would be far more reliable, but too bad there are too many gay Emission laws that they have to follow. CAFE anyone ?

nycgps

iTrader: (1)

I dont see anything wrong with using Mobil1. The only reason I never really use it simply because they're expensive. compare to other good Synthetics say Royal purple, they cost at least a buck more. yeah yeah a buck wow, but I buy them in 30-50 bottles at a time, and I have 3 cars at home. you do the math.

Mobil1 got such *bad name* simply bcuz what happened 30+ yrs ago. 30+ yrs .... a lot can change, tress got taller, young dude got old, babies back then are now Adult. What about oil technology ? much better than 30+ yrs ago.

oh did I mention that it wasnt really Mobil1's fault ? Its was Mazda's fault, they used the wrong material for O-rings. They changed it shortly after and never had a problem since. Ask Stealth1 he had that experience.

oh for me I use BP Chase card, 5% rebate @ BP, not bad. and I will cancel it when the deal expires and *reapply* for a new card. lol

robrecht

I think you're being a little unfair, rg has been very clear about this being his hypothesis.
Semantics. Anything that can be improved is an "issue" or even a flaw, the only question is whether an issue is worth fixing and apparently it was in Mazda's judgement. If you want to talk about relative degrees and margins, you really need some data, which Mazda and other manufacturers never make available. But presumably they saw enough problems that a change was indicated.

rotarygod

He's entitiled to his opinion. I'm not offended and he's not being unfair to me in any way. He is correct in that I wanted this to be a discussion. However when it comes to evidence, I believe I have brought forward an overwhelming amount to support the hypothesis though and I personally find it highly disturbing enough to consider it all more than purely coincedental.

Yes I do point to upcoming changes as proof. I also point to all of their omp reflash attempts, as well as evidence by expo1's engine teardown which even Mazmart appears to agree with.

The Mobil 1 issue isn't something from 30 years ago that's still around. It's something current. He's never talked to who I've talked to and therefore doesn't know why it is still an issue even though I have only relayed everything I have ever learned to the rest of the forum. I personally wouldn't use it.

Just remember, not everyone on the road has insurance. It doesn't mean I'm not going to though.