Wednesday, July 1, 2015

RX-8 Buyers Guide: How To Hit The Apex Without Getting Clubbed By A Seal

Words By DT Contributor RyanM:

Man, I miss my RX8.

If you're a gearhead / amateur grease monkey with an engine hoist, there's no better deal out there right now in the sports car world than a first generation (SE3P) 2004-2008 Mazda RX-8 . Just go into it with the right mindset and expect to spend $2k on the thing every 10 years. And throw what you know about engine maintenance out the door. They're still a Mazda, so the components of the car are solid - expect above average reliability from everything except the engine.

The bottom line here is to go into the RX8 experience with your eyes wide open.  Don't go into it expecting an economy car and economy car reliability.  Go into it expecting the reliability of an exotic, with the driving dynamics of an exotic, and engine maintenance costs (and frequency) of a Land Rover. 

The problem with the RX-8 isn't the cars themselves, it's owners who don't understand that owning a rotary is different than owning a piston engine'd car. Thus, you can find low compression examples that are still in great shape and fully loaded but need an engine for pennies now a'days.

It's an awesome car, think of it as a heavy Miata with a roof and a back seat. I loved mine, I only sold it because I had performed a few modifications and realized it would never pass smog when I moved back to CA a few years ago. As far as I know my former car is still in its 3rd owner's hands, and he's loving every minute of it. He premixes. is where I got most of the info (and support) needed to buy a slushbox equipped RX-8, (and do an MT swap) and if you buy one of these that already has a manual transmission, good news, all you have to do is pull and replace the engine which takes even less time.  There's also an RX8club FAQ that is probably a ton better than the disjointed drivel I'm about to spew forth (and this one too.)

First off, forget all you know about piston engines when dealing with a rotary.  Here are some examples of the differences.

1. By design, these use oil, around 1.5 - 2qt per 3000-5000 miles. Here's a video by EverydayDriver on youtube that talks about how they used almost 1/2 qt of oil in one day of hard driving.  Oil is cheap, don't worry about it.

2. The Renesis 13B-MSP (2-rotor, multi-side-port) Wankel engine burns oil as a part of the combustion process and thus, go through catalytic converters like a MoFo - 60k is a good estimate if you premix.

3. DO NOT USE Synthetic oil.  Good for pistons, not good for Wankels.

4. Premixing 2 stroke oil or specifically designed Idemitsu premix actually helps these engines last longer.

5. A redline a day keeps the carbon away - carbon in these cars is the enemy of compression..

6. Hot starting.  If the seller professes the engine to be "new" or have "good compression", a true test of whether or not the engine you have is going to last more than just a year or two is to get the car good and hot and turn it off.  Wait about 30 seconds to one minute, then try to start it (as if you were filling up your gas tank, or running into the store to grab something real quick.  If it starts right up, you're usually OK in the compression department.  But to double check / ensure that you're good, get a legit compression test.  Using a normal, piston engine'd compression tester will not give you an accurate result.  In order to gauge compression accurately, these engines need to be at a specific temperature, with the rotors spinning at a precise RPM (or at least normalized to that RPM by a rotary compression tester).

7. A word about compression and hot starting.  These actually start easier when *cold* believe it or not.  I won't bore you with the details but the TL;DR version is that the epitrochoid shape of the rotor housing expands and contracts with heat, and when it expands it pushes the walls of the rotor housings slightly further away from the apex seals.  When the seals are on their way out they out, they can no longer make contact for long enough to ensure sufficient combustion.  Same is true but to a lesser extent for the side seals.

8. 1.3L of displacement is a bit misleading.  A normal 1.3l engine would return favorable fuel economy and have low emissions.  The displacement of 1.3 liters is one thing, but you get twice as many combustions per revolution - so it's technically, for emissions purposes, a 2.6l.

9. You've probably heard me spout off about "the horsepower of a V6, the torque of an I4, and the thirst of a V8."  Yes, yes, and yes.  But when you're elbow deep in a flat out 3rd gear corner edging closer to 9kRPM in one of these things that you've done all of the work on yourself, none of that really matters.  These cars are an absolute scorching deal right now if you're handy with a spanner and you go into it with reasonable expectations.  I would also budget for a copy of Cobb's Access Tuner - Race, and a Cobb Access Port to modify MOP tables and suppress CELs from when you inevitably have to gut the cat.

My thought is that the reason these cars have such a bad rep is that people buy a 6 year old example for $4000 with a knackered engine but they expect it to act lil' like a 6 year old piston engine'd car.  There's a lot of misinformation out there, too. But there is good news though, everything else is pure Mazda - brakes, suspension, steering, components, sensors, interior, etc, all of that is good to go and requires little maintenance.  If you get a Grand Touring, there's all of the amenities you'd expect in a $40k car, for under $3000.  Leather, satnav (optional), 6spd manual, limited slip diff, TCS, Stability control, heated power seats, awesome audio system, large sunroof etc.

As far as market references if you'd like to focus on two distinct categories of RX-8 that would be a start.  One category is the 100% running and driving examples that are either obscenely low mileage OR had their engines replaced by Mazda during their 100k engine warranty extension program (though there are a few notable - and vocal on the forums - exceptions, generally there's no such thing as a 120,000+ mile RX-8 on its original engine that I would feel comfortable relying on as daily transportation).  The other category is the cars that need engine replacements.  Sub categories to the latter can be buy a used engine, buy rebuilt from a reputable shop, or rebuild yourself.  Don't buy an auto.  Ever.  Unless you're planning on doing a manual swap like I did.  The 2006+ auto had a 6 port with 212bhp. '04-'05 autos had a 4 port that supplied 189-ish bhp depending on who you ask and believe it or not, slightly more torques.  Typically the 6 ports have more vac lines due to the APV/VDI (the 4 port only has the SSV). One way to tell would be to look at the dash cluster in the car. Redline at 9k = 6 port, redline at ~7k = 4 port.

A quick scan of my local classified produced a dozen RX8's in the 80k - 120k mile range, all Grand Tourings (leather, heated seats, LSD, sunroof, etc) all below $3000, all needing an engine but otherwise in good shape.  For reference 2 years ago I bought a 2005 base RX8 that needed an engine for $500 and some entertainment system wiring work.  I bought a JDM engine and trans for $1200 shipped.  I drove it for a while and sold it for $5500.

Dynamically these cars are awesome.  They feel like they rotate around the gearshift knob, they can rev literally forever (though they stop making power above 10krpm I've been told), and they are suuuuper smooth.

You can search any craigslist and find piles of cheap blown-engine RX-8s, but just for illustrative purposes, here are a few.

Here is a  2005 Mazda RX-8 automatic covered in Japananime style graphics with a grenaded engine and offered for $3,000 in Long Beach, CA.

The next one is a 2005 6-Speed  offered for $5,000 in Lakewood, CA with a nasty throw out bearing sound and cabin that smells like gear oil.

Here is a  2004 6-speed with "strong running 120k mile original engine" that doesn't smell like gear oil, offered for $4,500 in Elk Grove, CA.

Here is a 2004 automatic with a busted engine, offered for $2200 in Oxnard, CA...but this is just a quick snapshot of cars -- just head to your local list and find something cheap, it isn't like you are searching for a stock STi or non-salvage title E36 M3.

If you can find a 6 port 6-spd Touring or Grand Touring car with a toasted engine for under $3k, and a low mileage used-but-tested-good engine for $1500, I'd say you got yourself a sweet deal for under $4500 that you can flog the beans out of for 3 or 4 years before you have to think about hot start issues.

Speaking of hot starts, if you end up buying one of these ticking time bombs, you need to read up on the starter business here. TL;DR version -- Look for the newest p/n, these starters spin at a faster RPM and can stave off the dreaded rebuild (i.e. hot start failure) for a year or more.

One thing I forgot to mention earlier is that these things will flood if you shut them off after a cold start before the engine has a chance to fully warm up.  Or they will flood on a hot start if you have really low compression.  To cook off the cat they dump fuel in on a cold start.  If you shut it off before the engine is fully warmed up, the excess fuel in the chambers will wash the oil film away from the rotor housing surface (where the infamous "apex seal" does its thing) and cause a low compression condition.

If you're going the used engine route, I implore you to have the compression checked with a rotary compression tester.  I'm not going to get into the intricacies of how they work because there are a dozen youtube videos out there showing exactly what happens and why.  

If you're going the rebuilt route, 2 words: Rotary Resurrection.  Or even if you go used, you can sell Rotary Resurrection your old "keg" (what the rotary "block" looks like) which is what I did.  He paid for shipping, and gave me ~$200 - 250 for my knackered old engine.

After selling spares from the swap (duplicate pulleys, injectors, throttle body, sensors, alternator, MOP, MOP lines & injectors, harness, ECU etc) I ended up only paying $700 for the used engine.

Another note: sometimes you can get lucky with a car that the owner says "won't hot start" "just stalled on me on the highway" or floods... check the model number on the starter and check the health/age of the battery.  Even if both look new, check them.  While I was acquiring parts for my swap I was actually able to daily drive the car after I replaced the battery with an older (but still 100%) Optima red top I had laying around and upgraded the starter to the latest and greatest.  I also de-carbed the car a few times.  

Every now and then you can get lucky and decarb these engines (much more involved than just sticking a vac line into a can of Seafoam and bouncing it off the rev limiter for a few minutes) and regain some lost compression.  Carbon (due to unburned fuel + the oil required by these engines to lube the apex seals) can over time decrease compression enough so that it won't hot start.

Most cars have timing belts you change out every 100k and if done at the dealer will cost $1000 - 2000 (like my Audi...).  If you play your cards right, you can get a good used replacement engine for that much dough -- wring another 4 - 5 years out of it, love every last second of it, and sell it along for about what you paid when you're done.  But don't go in expecting to make any money.  And don't go in expecting it to be easy (though it isn't hard).  I put myself through college (before I joined the military to pay off my loans) wrenching on cars, so I'm fairly handy and I do have a garage and full set of tools.  HOWEVER All I really needed to pull the entire engine AND transmission from this car in under 4 hours was a $29.99 100 piece made-in-China tool kit and a used $100 engine hoist.  I think I had to buy one 22mm socket for the PPF bolts.  That's PPF for PowerPlantFrame... yep the same thing as in a Miata.  I didn't even have to discharge the A/C I just moved the compressor out of the way.  It takes me longer to pull the engine in my Volvo and I've done that a dozen times.

Lastly, if you're ever down on your luck and pissed at the car, check this video where they took an RX-8 and put it up against a BR-Z/FRS back when the BR-Z/FRS came out.  Even though it was a few years older, it actually held up admirably to the Toyobaru twins... and providing you can get one in good shape just needing an engine, it should cost you much less than a Toyobaru as well.

That's about it.  If you want to look at 1st gen RX8 vs 2nd gen RX8 that's fine but if you're going to stick around  the $2500 - 5000 "all in" budget, I think the 2nd gen RX8 will be out of that pricerange.

DT: Big thanks to RyanM for taking time away from his newborn baby to write this article and help save a few RX-8s from the junkyard. All images from, except craigslist where noted.


  1. Fantastic write-up, RyanM. Really great information. I was particularly interested in what you had to say about how much a used engine costs.

    1. And I hope things are going well with the new bambino.

    2. Your article got me curious, as usual, so I looked to see what was available in my neck of the woods. Prices ranged from $4K for a rolling shell all the way up to $14K for a pristine example. That seems right in line with what you wrote but the really interesting thing was that of the 10 cars for sale, exactly half of them had salvage/rebuilt titles.

    3. Hey K2, check Dallas / Ft Worth craigslist. They're like roaches down there under $3k. It's my closest large metro craigslist now that I've moved to flyover-ville. And yes, a LOT of these are salvage, usually due to people slinging them off of the pavement because the car's ability exceeds theirs as a driver.

    4. Interesting! I'd imagine there are a lot in SoCal.

    5. K2, it appears this captcha will only let me reply to you but while this works let me say Tanj knows what they're talking about and thankfully got into much more detail than I was able to in a mass-consumption (ish) writeup.. Also let me thank Vince and Chris for stitching together 30 minutes of brain dump into something readable for said mass-consumption. It was really unreadable drivel until they patched it up.

      Next, there are a lot in SoCal for sure but lately they all seem to be autos of the '04 - '05 variety.

      Hopefully the computer I'm on decides to like Tanj's posts tomorrow...

    6. @RyanM - Oddly enough I'm in DFW. I've come to the conclusion that it's sort of a mecca for rotary bits as far as the used market goes. Tons of FCs available. SA/FBs are pretty common. FDs pop up often enough and yes lots of blown RX-8s. Also nice to have two internationally known rotary tuners. You should also check out OKC. Very large RX-8 contingent there based on the enthusiasts. Check out North Texas Rotary Enthusiasts (i'm a moderator) and Oklahoma Rotary Enthusiasts if you're on FB. Both groups do a good job of posting up finds and a fair amount of cross over between the groups.

  2. +1 on a fantastic article.
    After waiting many years for my vaporware Mustang II front suspension for my 1800ES from Swedish OPS I started looking at other front suspension options.

    As I whittled through my options I settled on a Miata front suspension as the best choice. Then I thought darn that 1800ES solid rear axle suspension is really going to limit the handling characteristics. So next I was researching what total rear suspension sub-frame could be easily grafted into the rear portion of the car. Finally I had to ask myself what did I really want to accomplish and at what budget.
    I really love the look of the 1800ES but the project time & money budget was extremely high if I made it into a monster for the twisties. OR… I could just start with an alternative car that is 90% there already and tweak it.

    So next I researched used sports cars that fit the handling department at a reasonable cost. My short list was the Mazda RX-8, Mazda Miata, Honda S2000, BMW Z4, Porsche Cayman, and Porsche Boxster.
    I then narrowed it down between the RX-8 and the Miata.

    Ultimately I picked the Miata because of the large production numbers that created a large aftermarket and forum support network. I was not buying a collector car, I was buying something to enjoy and continuously tweak.

    That said, the RX-8 was very high on my list.
    From my RX-8 research I was planning to buy a 2009 or newer R3. The suspension had structural improvements and the biggest engine problem was resolved with the 3rd oil injection port. All it really needed was CAT delete, a little pre-mix, and keep replacing the ignition system regularly.

  3. Awesome article Ryan---I've also noticed how cheap these have gotten, and in doing a little research have found a reputable shop (rotary resurrection) about 3 hours from me in Knoxville, TN who will do a complete rebuild for $1600. It's really tweaking my "hmmmmm" factor. My only problem is that I would want the car to be able to perform well at DE events, and I still haven't heard how well these hold up in that duty---there doesn't seem to be, or I just can't find, a large contingent of owners of these who track them. Given the fact that track rats will jump on any car that's worth a darn on the track and costs less than $5k, it makes me wonder about their suitability to the purpose.

  4. I’m going to chime in with a few things as a rotary owner but not a RX-8 owner (I’m an NA FC guy). First of all excellent write-up, it does an excellent job of introducing RX-8’s to non rotary folks. The biggest killer of any rotary is failing to do proper maintenance on the car. Unlike most cars a rotary is very unforgiving about maintenance. You’ve got to do it, and do it religiously. Overheat the motor, plan to replace it. Don’t check the oil every time you fuel, expect to replace it. Replace the coolant on schedule, etc. I would highly suggest you premix or run an OMP (oil metering pump) adaptor that uses premix from a separate reservoir instead of engine oil from the crank. There is nothing wrong with using quality modern synthetic oils. Except remember you’re burning it so that adds to your cost. If you’re using an OMP adaptor it’s definitely a good thing. Rotaries typically don’t suffer from bearing/friction related failures (except for side seals) so you don’t typically need fancy oils for that purpose. You do want fancy oils for the heat though. Rotaries generate more heat than most piston petrol engines. EGTs of 1600 to 1900 *F are not uncommon. (Another reason the cats have limited life spans. And why the FCs at least had a cat temp warning light because hey, sometimes they catch on fire and burn your car down.) The oil cooling systems on rotaries typically are designed to expel a third of the heat generated during the combustion process.
    The Renesis motor is nowhere near as reliable as the earlier 12a/13b NA motors. With proper care and feeding an earlier motor can do 150k to 200k before compression issues become a problem or you lose a side seal. The Renesis just isn’t going to do that. I fully agree with using Rotary Resurrection to get rebuilt motors and/or selling off your bad one. The guy does excellent work, is affordable, and an amazing asset to the rotary community. As to buying used engines USDM or JDM, don’t. Or at least go into it with your eyes open. The JDM engines aren’t any more reliable than the USDM. As a used motor they are just further down the path of needing to be replaced. You’re better off spending that cash ($1.2 to 1.5k) on rebuilding a blown motor than you are buying the JDM one. To my knowledge no JDM engine importer offers any sort of warranty of rotary motors even if they do typically offer a warranty on piston motors (if you know of one that does let me know). It’s just not worth the risk since the engine has to be in a car or on an engine test stand in order to properly test the motor. Do look into buying a JDM motor if you need parts.

    1. Agreed.
      The main reason for the engine problems pre-2009 is because Mazda was trying to limit emissions by limiting oil usage. That did not work out well. The car (and the rotary in general) was pulled from the market because it was having problems meeting emissions. Low sales did help that decision. It is really unfortunate because that Mazda did not modify the RX-8 to a piston engine.

    2. Any way you slice it, it is AMAZING to me that this is a car that made it to market, given the care and feeding required of a car being sold to a mass market audience. To me it either says that a) Mazda is truly devoted to their performance heritage and their enthusiast audience, or B) Their product planning and marketing departments are closet masochists. The enthusiast in me chooses to believe in B. ;-)

    3. Care and feeding for the Renesis isn't any higher than the prior rotary cars. It's just a poor fit with the american market and the mindset that you just buy a car and never open the hood.

  5. On the subject of compression testing. The primary reason for the need for a rotary specific tester for the RX-8 is the starter motor upgrade that’s mentioned. All the rotary peeps prior to the RX-8 can get away with a modified piston engine tester because everyone’s engine spins at approximately the same speed. So it’s typically an apples to apples comparison. With the 8, that may not be quite the case and you do end up needing to know the RPM in order to adjust the compression numbers. Expect to pay around 150 to 200 at a dealership to have it tested. Some aftermarket rotary specific testers do exist, and enthusiasts also have some older factory testers as well. None are cheap ($300 to $800), but useful if you’re a rotary addict. (I do own a rotary specific tester.)
    One the subject of carbon buildup. This is one of those things that I feel the rotary community has turned into a boogey man. The only way it reduces compression is when it causes a catastrophic failure of a side seal. Carbon buildup occurs due to the injection of oil into the combustion chamber for lubrication and not completely burning it during the combustion process. So what happens is the American public, averse to red lining (or running the engine high into the RPMs) drives the car like your typical piston engine at low to mid RPMs. Over an extended period of time this can cause carbon to build up in the rotor housing. The fear is a piece of carbon breaks off and damages a side seal, causing significant compression loss. The other fun one that can happen is carbon lock. Instead of damaging the seal while the engine is running, it instead wedges itself between the rotor and housing causing the engine to become locked up and unable to spin to start. Typically it takes quite a long time for you to have carbon buildup of this magnitude. And simply just driving the car into redline will take care of this issue. The other old school way is to disconnect a vacuum line and suck in about a gallon of water into the rotor housing while the car is running. The steaming process will gently break up any carbon. This might be something you do as part of a tune up on a used car you buy but shouldn’t really be necessary otherwise.

  6. Last thing, about engine flooding at startup due to not warming up the engine. I’m going to put this up there with another thing blown out of proportion by the rotary community. Can it happen? Yes. What’s the primary cause? Typically low compression and/or leaking injectors. This isn’t something you should expect to see on a healthy high compression engine. So this is what happens. Unlike a piston engine, where excess fuel sprayed into the combustion chamber will eventually drain past the piston rings into the crank case, in a rotary it ends up pooling at the bottom of the housing (and doesn’t evaporate). When the engine is cranked the side seals pick up the pooled fuel and slosh is around quenching the spark all the while you’re adding more fuel to the process. Yes some is lost through the exhaust ports but not as much as you’re dumping in. So you end up shutting the car down while it’s still in cold start enrichment trying to get the cat to temp. You end up with some excess fuel in the housing. You let it sit for 10 - 15 minutes when you run into the store. The engine heat soaks a bit from the limited time it ran. Housings expand and your compression lowers. You jump back in and the car sprays extra fuel for the starting process. That extra fuel, your lowered compression, and the extra fuel sloshing around quenching the spark all combine to cause a non start flood situation that’s self reinforcing. I suspect the RX-8 is like the later FCs and FDs in that you can turn off the fuel injectors buy pushing the gas pedal all the way to the floor during startup. The normal procedure is to crank the car 10 times for brief intervals while turning off the injectors. Then crank the car as normal with the injectors working. Cars prior to the RX-8 also suffer from leaking injectors. As the injector ages it no longer holds fuel back at pressure and it seeps past the pintle. So when the car is shut off fuel dribbles into the housings from the residual fuel pressure. When this starts you can rev the car to 3 to 4k and shut it off at the higher rpm. That lessens the fuel pressure after shutdown and the spinning rotors can help displace any immediate left over fuel from the housing.
    Mazda improved the reliability of the engines in the second generation RX-8 (09+) by addressing the lack of lubrication which was causing the side seals to wear at a faster rate. They should last longer than the earlier engines. They still have all the same care and feeding requirements, and still don’t last as long as the earlier 13b’s but they are an improvement. Unfortunately you typically don’t see them available for the change you find in the couch. But if you do find one with a blown engine for cheap it’s a worthwhile upgrade over the earlier cars. Rebuild expenses are the same.

  7. Damn. Lost my comments to FTB.

    Short recap. RX-8 makes a fine track car. I track my FC and have been working for a HPDE group for 9 years. Our instructors and students have run them. The RX-8 is a overweight Miata that's lacking torque. Biggest complaint from everyone is it doesn't have enough power (i.e. torque). The reliability issue is a big negative especially compared to a Miata which will do 150k+ and keep on tracking. The other thing that has to be addressed is cooling. Rotaries dump a lot of heat. The cooling system (and oil coolers) needs to in perfect order and beefed up a bit (cooling system). Running a rotary hot is a great way to loose coolant seals.

    All that being said everyone praises the handling of the car. Very neutral with no bad behaviours. It just needs more grunt.

    1. Thanks for all the feedback Tanj!.....good info, all. You sort of confirmed my suspicions, that, on track, the RX8 is a MX5 with a weight penalty and higher running costs, which is probably why they're still fairly rare at track days. Thanks again.

  8. The charm of the RX-8 is it's balance.
    However the power is lacking as mentioned.
    Question: Has anyone made a comprehensive kit to install another powertrain into the RX-8?

    1. Speaking of balance, it's interesting to compare this to a 944.

    2. Rene, as a matter of fact........

    3. The primary issue with doing engine swaps is the power steering rack is electric and controlled by the factory ECU along with all the gauges in the dash. There have been projects to do swaps but I've seen very few successful commercialized.

  9. Great write up RyanM! Thanks for contributing it.

  10. Great article! Of course I had to look on the local craigslist after reading it....local shady used car dealer has a 2004 manual for $1600 with 143k miles, "runs great but stalls out after 5 - 10 minutes"...assuming this needs a new engine/rebuild. Don't have the room to do a rebuild but still tempted to buy it and park it somewhere until I do.


    This was so excellent I had to steal it!
    CLUBBED BY A SEAL from McMike

    1. Yeah, Ryan. Kudos for the Jalop repost!

  12. Thanks DT, just what I needed. I love these things but as soon as I read "spanner" and "pre-mix" I got very nervous. I always thought spanner was a type of bridge and the only pre-mix I know of is what I do with Bloody Mary's before a picnic.


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