Mazda RX8 Rotary - Completely Different Beast

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The rotary engine is known for premature failures even with good maintenance. I'm not sure if the latest rotary (RENESIS) is any worse, or better, than its predecessors. However, the RENESIS history is sorted at best, and is still evolving. Early copies of this engine had both quality control issues and unacceptable levels of oil being administered by the OMP (oil metering pump). Mazda has addressed both with increased quality control and improved OMP control algorithms and have thus extended warranties on this engine to 8 years/100,000 miles (all of them are covered). I have no idea what they did for those customers who already paid for engine replacements after their standard warranty ran out.

Having said all this, 140,000 miles on an RX-8 engine seems to be beyond expected engine life. So he did well. I've heard some engines dying after just 15,000 well cared for miles.

The regimen for making these engines last are:

(1) Frequently revving to redline to clear carbon from the exhaust ports and the apex seals. Additionally, some will actually use Seafoam to clean carbon from the engine and do it every 15k or so.
(2) Frequent oil changes. The use of synthetic is highly contested by owners but Mazda does not recommend them.
(3) Infrequent idling.
(4) Change plugs and coils as per owners manual, or sooner. Do not use cheap plugs, use the NGK Iridiums only and they are VERY pricey.
(5) Run a premix that both cleans and lubricates. At 200:1 mix ratios. This can be Idemitsu premix, FP+, or other two stroke oils advertising low ash and meeting JASO FC/FD standards.


From what I can tell, there is apparently little/no cure for hot/dry climates. So if you live in Vegas, stay in Vegas, just don't own an RX-8 unless frequent engine replacements excite you.
 
Originally Posted By: artificialist
I'd be afraid to buy one of those cars. I had a customer get their RX-8 towed in for a no-start condition, and compression was at 30 PSI on the front rotor, 40 PSI at the rear. Far lower than the minimum 120 PSI the manual calls for. This car had 140,000 miles on it!

What is really sad is that the guy had oil changes done every 3000 miles with 5w20 regular Pennzoil, and everything other maintenance specified by the dealer was done.

A Honda S2000 would behave much like a Mazda RX-8. If you can go without rear seats and suicide doors, that would be a better choice.


Was his RX-8 stock, or modded?
 
That's strange, because I have seen these engines with upwards of 200,000 miles on them. Including the infamous turboed rotaries from the last generation of the "supercar" RX-7s circa the early 1990s...
 
sounds like the reliability got worse. I sold my '86 RX-7 with 177,000 miles and it ran as well as when I bought it with 46,000 miles. Never had any issues other than burning through clutches and a lot of oil.
 
Originally Posted By: typ901
sounds like the reliability got worse. I sold my '86 RX-7 with 177,000 miles and it ran as well as when I bought it with 46,000 miles. Never had any issues other than burning through clutches and a lot of oil.


They didn't. Some just had owners that couldn't drive 'em.
 
I had a rx8, I know what Im saying.

The Rotary engine is nothing special. it's been around for a very long time. The rotary is not used in 99% of the cars being made today because:

the motor is Really bad on gas, it is not very reliable, it dose not make any good Tq. and the Hp. it puts out is not enough to move fast enough.

It is a really cool design, but thats it. The motor has no other reason to be made other then it is a cool design. so mazda makes a car, that has a cool designed motor in it, for people that want it.

There is a reason BMW, Mercedes, Lambos, lotus, Bently, Rolls royce, porcshe, GM, Ford(other then the mazda rx8), toyota, nissan, ect. . . . do not use a rotary motor. They are not good at anything! They put out bad HP+Tq, bad MPG, and they are not the motor to count on for the long run.

The good old piston engine is the best design for a car, thus all auto makers use them.

rx8 is a nice car, but it is not as fast as it should be, it gets worse MPG then my V10 truck, and ALOT of them get/have motor issues.
 
I did some google searching on RX-8 problems and there were lots of folks whose cars would just die while making a left, merging into traffic, etc. Scary stuff. Surprised that isn't a class action on these things. Some in the owner's boards stated they were on their 2nd and 3rd engine with engines [censored] the bed at as little as 30K. Yikes!
 
Hi,
I had a little to do with the Mercedes Wankel powered prototype cars (C111s) and many reasons eliminated them from serious production consideration. The four rotor (each 600cc) version developed around 350hp and was good for 300kmh (190mph). Emissions, fuel economy and operating and production complications killed it for MB around 1973

Toyo Kogyo (now Mazda) have perservered. I covered many miles in RX2, RX3, and RX4 versions, both saloons and coupes in the early 1970s. They were great to drive and performed better than the Alfa GTV 1600s of that era. I disassembled and reassembled many of these Wankel engines. A problem then was the wiping speed for the side seals and cold start drag - this caused excessive seal wear. They were reliable if you operated them correctly - and an employee of mine raced a RX3 Coupe for some time with great success

In 1991 a Wankel powered Mazda won outright at Le Mans

Felix Wankel died in Heidleberg in October 1988. His personal car a Mercedes 350SL (powered by his own engine ex the CIII prototype)developed 320Hp and was good for 240kmh (150mph)

Perhaps the best fuel source for the Wankel engine would be hydrogen

A close friend of mine has just sold his RX8 after three years and 80kkms (50k miles) of very reliable use. His only comments have always been "it is hard on fuel" - he now has a hot Mazda 6!

Mobil advise against using any of their synthetic lubricants in the RX7 or RX8. They recommend a semi-synthetic or mineral lubricant of 10W-40, 15W-40 or 20W-50 viscosity

Knockers of the Wankel engine should do some homework - there are many happy users. I was but one
 
My mom had one of those early RX's in the 70's, she had loads of electrical issues but never an issue with that engine. Wish I could've seen the car!
 
Just took possession and I love it, not so quick in a straight line but a rocket in corners! Its got 52,000 kilometers. The mtf, diff, oil, air filter,& cabin filter will all be attacked tomorrow.

What is with the debate over using 20 weight? Why would Mazda spec such a thin oil when older rotaries spec'd 40 & 50 weight. CAFE standards or the design of the Renesis engine?

I'm still on the fence on this oil weight issue.
 
Congrats on the purchase. Dont let some of the comments scare you. The newer rotaries are far more reliable than they used to be. The 3rd gen RX7's with the twin turbo motors, were prone to failure, and helped give them a bad name.

Stay on top of your maintenance and oil changes. Also, filters, and plugs as well. I would recommend going to mazda for things like plugs, because auto parts stores probably wont be familiar witht he rotary. If I remember right the older motors had two different sets of spark plugs. Two were hotter than the others. It may be the same for the renesis.

As for oil weights, I would jump on a rotary specific forum and see what those guys are running. BITOG is the best site going!, BUT, there may be a general concensus on the mazda boards as to what oil to run in the new motors.
 
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digitalSniperX1 said:
Change plugs < 30k miles. Use nothing but the NGK Iridium's that they come with. Don't even bother trying to save money on plugs, rotaries eat them up. They cost about 100 dollars for 4.

Check out sparkplugs.com. The iridiums are much less than $25 per plug there.
Click to expand...
 
Doug Hillary said:
Hi,
I had a little to do with the Mercedes Wankel powered prototype cars (C111s) and many reasons eliminated them from serious production consideration. The four rotor (each 600cc) version developed around 350hp and was good for 300kmh (190mph). Emissions, fuel economy and operating and production complications killed it for MB around 1973

Toyo Kogyo (now Mazda) have perservered. I covered many miles in RX2, RX3, and RX4 versions, both saloons and coupes in the early 1970s. They were great to drive and performed better than the Alfa GTV 1600s of that era. I disassembled and reassembled many of these Wankel engines. A problem then was the wiping speed for the side seals and cold start drag - this caused excessive seal wear. They were reliable if you operated them correctly - and an employee of mine raced a RX3 Coupe for some time with great success

In 1991 a Wankel powered Mazda won outright at Le Mans

Felix Wankel died in Heidleberg in October 1988. His personal car a Mercedes 350SL (powered by his own engine ex the CIII prototype)developed 320Hp and was good for 240kmh (150mph)

Perhaps the best fuel source for the Wankel engine would be hydrogen

A close friend of mine has just sold his RX8 after three years and 80kkms (50k miles) of very reliable use. His only comments have always been "it is hard on fuel" - he now has a hot Mazda 6!

Mobil advise against using any of their synthetic lubricants in the RX7 or RX8. They recommend a semi-synthetic or mineral lubricant of 10W-40, 15W-40 or 20W-50 viscosity

Knockers of the Wankel engine should do some homework - there are many happy users. I was but one
---------------------------------------------------------------


This rotary thread got me going down memory lane:

+1. The Wankel rotary is/can be a great engine. I believe that it may be possible that some owners do not know how to operate them to get the best performance or longevity. I have owned 3 early 80s RX7s (I turbo'd the '84) and one 1972 RX3. The RX3 was the greatest stealth car I've ever owned. Looked like Toyota Corolla of the time and it would just dust other cars like the 240 or 280z's. The manual throttle and choke hand controls were unusual and fun. It was a backfiring monster. But it would rev. No rev limiter in those days. Just wind it up and the rev buzzer would go off at about 9000 rpm--and it would just keep spinning. The thing would do 130MPH. My dad sold it while I was away at school. Had about 90K hard miles when sold. It's the one car that I owned that I really wish I still had, just because it was so different than anything else on the road.
Click to expand...
 
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I think what everyone has said both positive and negative about these rotaries are true with one exception. Someone posted 'there are no advantages to the rotary design'.

That statement is basically not true. They put out huge power/liter which keeps the size down. The compact size of the rotary engine and its only three moving parts are its advantages (one might say its apex seals are also moving parts but then so might be piston rings). Its compact size allows for lower weight and lower center of gravity which has obvious advantages in sporty cars.

However, the disadvantages stated here are basically true. These things burn way too much fuel especially when not at a highway cruise. Those of you who think there are no issues with reliability I too believe are incorrect. There are many reports of engines dying at 15,000 miles, essentially no modifications. No, this is not the norm. But to hear engines dying at this young age is very rare, and the number of them dying is far higher per unit sold than anything I've ran across, including Vega's.

One large negative about them is they often give little warning when they die. They sometimes die almost instantly due mostly to apex seal breaking which causes instant loss of power and generally catastrophic damage to the rotor housing(s) and rotor itself.

Having said all the negatives I'm not victimized by any of them, knock on wood. I drive mostly highway and get about 20mpg. Not terrible, but certainly not good. I have 14,000 miles on mine and it hasn't died yet. I also have a 100,000 mile warranty on it if it does. I also have a realistic expectations for this engine. It's not a matter of if it goes, it's a matter of when. And I'd bet 10dollars to 100 that it won't last anywhere near what a Honda Accord engine does. I'll be keeping tabs on its compression like I've done with no other car I've owned.

Oh, I hope you enjoy your RX-8 as much as I do mine.
 
Originally Posted By: digitalSniperX1
Change plugs < 30k miles. Use nothing but the NGK Iridium's that they come with. Don't even bother trying to save money on plugs, rotaries eat them up. They cost about 100 dollars for 4.

Probably should just change the coils as well at 30k. The coils in the RX-8 are junk. Some replace them with GM LS-2 coils for about 375 dollars and those are far superior to Mazda OEM's.

Premix with 1.5oz FP+ and 4oz. Amsoil Saber Pro at 12 gallon fill ups.

One Italian tune up per tankful, or more often, i.e. rev it to 9000rpm for several seconds and get there with WOT.

I live in Florida, so I simply drive it easy for 4-5 miles prior to revving it to anything past 4k rpm.

Oh and don't buy a 2004/2005 unless it has very few miles and the latest PCM flashes done as soon as they were available (MSP-16 I think is the latest reflash).

A couple of other things....DON'T BUY AN AUTOMATIC. For some reason, perhaps simply people don't drive them hard, or they have just one oil cooler, they are much more prone to engine failure from what I've read. Also, if you live in a hot dry climate (or plan to move to one), buy another car. From what I've read, rotaries a short life in hot & dry climates (I didn't notice where you live).

And finally...if buying an RX-8 is a financial stretch for you....don't buy one. They burn gas like a jet engine (babying it at 65mph cruise you'll be lucky to get 22mpg, if you drive city, I've seen numbers as low as 11mpg). Additionally, they are not cheap to maintain.

This description of a rotary engine makes me want to run out and buy one!!!!
 
Originally Posted By: rg200amp
I had a rx8, I know what Im saying.


Well, so have others, like myself (though only briefly, a friend loaned it to me).

Quote:
The Rotary engine is nothing special. it's been around for a very long time. The rotary is not used in 99% of the cars being made today because:


It's true that the rotaries gets lousy fuel economy for its size. Supposedly Mazda is working on the next gen. and will increase its size, power, and fuel economy by 2011 0r 12...

And one of the key reasons that Wankel engines are not used in 99% of cars is that Mazda has/had a proprietary rights to certain designs. And while anyone can make a rotary, they'd have to R&D a lot of it from scratch...

Quote:
the motor is Really bad on gas, it is not very reliable, it dose not make any good Tq. and the Hp. it puts out is not enough to move fast enough.


Um, a 1.3L engine displaces 238HP. That's very solid power vs. size and weight ratio. I agree that the RX-8 is underpowered compared to it's class rivals, but the engine is meant to be revved, highly. But the RX is also extremely light, agile, and only really needs a few more horses; which it will get eventually.

I might also add that one of the "problems" with the US variant is the emissions standards here draw about 20 horsepower off the car as compared to the Japanese version, which gets around 257HP, which suffices nicely as the car doesn't weigh all that much. It's meant to be driven in real world traffic, not at the race track - not the engine you can buy, anyways. And the car has a very high redline to compensate for the torque...

Quote:
It is a really cool design, but thats it. The motor has no other reason to be made other then it is a cool design. so mazda makes a car, that has a cool designed motor in it, for people that want it.

There is a reason BMW, Mercedes, Lambos, lotus, Bently, Rolls royce, porcshe, GM, Ford(other then the mazda rx8), toyota, nissan, ect. . . . do not use a rotary motor. They are not good at anything! They put out bad HP+Tq, bad MPG, and they are not the motor to count on for the long run.


Um, you have no idea what you are talking about. The reason they do not use rotaries is that Mazda has the Wankel design, and to my knowledge, no one else could even copy it up to a certain point. I'm assuming the patent has expired. But even if they can use the Wankel style, no one has done any R&D into rotaries so why would they go through the expense now? Even Mazda is too busy pumping out 3s, CX's, and the new gorgeous 6, to bother with the low volume car marketed to a very niche market segment. They can't even get the darn Mazda2, the darling of Europe, to the US except as a car Ford stole from them (ala the Fiesta!)

However, I will agree that the engine is dated and hasn't had any significant upgrades in at least 15 years or more. Something they are going to rectify in the next three years or so. There's talk of Mazda actually rolling back the RX number to the old "RX-7," and enlarging the rotary and significantly improving the horses and fuel economy as well. In turn however, Mazda is also said to be not looking to compete against the Nissan 300s or Shelby Mustangs. But instead trying to go back to the era of the "poorman's sports cars" of yesteryear, like the RX-7, the Datsun 280, Toyota Celica, and the Prelude USED to be in the 80s. So Mazda will produce a car that probably will be less than 300HP, but will allow you to use the car in actual real world commuting...

Quote:
The good old piston engine is the best design for a car, thus all auto makers use them.

rx8 is a nice car, but it is not as fast as it should be, it gets worse MPG then my V10 truck, and ALOT of them get/have motor issues.


And a lot of them don't have issues, and there have been some pretty [censored] piston engines out there. And just because everyone else jumps off the bridge, doesn't mean that_______________.
28.gif


Few have issues if they're properly cared for as rotaries have frequently surpassed the 100,000/150,000 mile marks with little difficulty and usually win the grueling, Lemans style 24-hour races...The only major engine issues I'm aware of is the use of the turbocharged RX-7, which burned itself up in the early 90s when Mazda stopped producing them for the supercar segment.

They don't get good gas mileage, but name me a true sportscar that does...If you looking for gas mileage, drive a Civic, or better yet, a manual Mazda3 i_Touring(30 mpg in combined driving according to Consumer Reports)!

Cheers, have a lovely weekend everyone!

04.gif
 
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Originally Posted By: Doug Hillary
...
Mobil advise against using any of their synthetic lubricants in the RX7 or RX8. They recommend a semi-synthetic or mineral lubricant of 10W-40, 15W-40 or 20W-50 viscosity

Knockers of the Wankel engine should do some homework - there are many happy users. I was but one



Mobil, on their old (circa-late 90s, early 2000s) US website, said use of Mobil1 15W-50 was fine in the RX-7 while Mazda was strongly against use of any synthetics at that point. Interestingly, I believe the factory fill now is probably Motorcraft 5W-20 --an advertised synthetic blend.

Cheers
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