Looking For Mazda Rotary Engine Expert

[Wrenchturner44]

Hello BITGOERs,

I have a chance to purchase a 2010 Mazda RX8 with 27k original miles. It is very clean and was most likely used as a pleasure vehicle.

Needless to say I don't have any experience with this engine or drive train. Current owner has treated it well and has told me how he has added oil to the gasoline when filling it up to help with rotor seal lubrication.

I have heard that this model was the most refined before Mazda killed it and the rotary engine. Yes, I am aware of all of the gasoline and possible coolant issues, as well as how you need to stay on top of maintenance. This would be used as a pleasure / weekend vehicle only by me.

Thoughts?

 

[dareo]

Buy it and swap in an LS or LT V8. The rotary at best is mediocre and at worst it turns the car into art deco.

 

[MRC01]

Back in the day I owned a '95 RX-7 (13BREW twin turbo) and raced it in SCCA. It was fast, fun and reliable. I drove it like I stole it and it saw redline on every drive. No problems, and that was typical of others who owned and raced this car. In SCCA, the RX-7s had fewer failures than the corvette and similar V8s. I also owned and raced a Panoz Roadster (Ford Cobra V-8) so I have experience with these opposite extremes of high performance engines: a turbo Wankel and a V-8.

You do not have to add oil to the gasoline. The twin turbo had built-in oil injection that operated at high throttle/RPM. The RX-8 has no turbo, so I don't know whether it has oil injection. But you definitely do not have to add oil to the gasoline yourself, and doing so is inadvisable.

With the RX-8, the automatic tranny makes less power than the stick shift. Something about the torque converter not being able to spin up to the RPMs of the engine. I hope yours is a stick shift. Also Mazda recommended against using synthetic oil. It was their opinion that dino juice burns cleaner than syn, with the 13BREW oil injection.

There is nothing special about maintaining these Wankel engines. They're reliable if you do the maintenance and drive them they way they were meant to be driven. They love to rev so keep it in the low gears and rev it. The Wankel engine has a unique response & feel different from most piston engines. Comments positive & negative here will reflect that.

PS regarding longevity: the SCCAers I knew typically got 80-100k miles out of the Wankel before it died. And that was the 13BREW twin turbo being driven hard in racing. The non-turbo in the RX-8 should run at least that long, if not longer.

 

[blingo]

Just expect to change ignition coils soon, better yet swap them for real upgrades. Failing coils can kill the cat which can kill the engine – and they often don't live that much longer than 30k miles on the Renesis (not really to be judged from infamous white spots on their bottom). Some GM-style coils could be okay, but that's a confusing field. Either way, plug-in or GM-style, better invest in a serious set of four as soon as you know you're going to keep the car. Beware of fakes, beware of poor high performance coils...
Engines are okay with revs but of course they too have areas suffering from revs, I don't really keep mine in low gears more than any other engine of so little torque.

 

[Lapham3]

I had an early version and it was a great car, but there were 'flooding' issues with these. As with starting it cold backing it out of the garage and shutting it off. You wanted to keep it going and driving to operating temps before shut down. As I recall the gas did seal damage. I seem to recall this was somewhat of a problem all along? I also understand that quite a number of the RX8s were re-engined by Mazda.

 

[RooflessVW]

Buy it and swap in an LS or LT V8. The rotary at best is mediocre and at worst it turns the car into art deco.

The swap into an RX-8 is a bit more involved than you think.

And the Renesis is a fine engine; you just have to make the entire ownership of the car a hobby.

 

[mazdamonky]

My family and I own several rotary engines. My dad sold them since the 90s and my grandfather actually met with Mr. Wankel and helped give some ideas for helping the motor work more efficiently and be more reliable some time in the late 50's.

Sadly I myself have never disassembled or rebuilt one, but I do know a lot about keeping them running and lasting a long time. 27k miles on a 10 year old car is quite low. Having a motor that low mileage isn't always better than having one with high mileage. As long as he drives it consistently and doesn't let it sit for more than a couple weeks at a time, it should be okay. These motors need to be started, ran, and warmed up to operating temperature often. Adding a little two stroke to the oil seems to help both corner seals and apex seals have a more reliable longer life. Contrary to advice you will get from many, wait for the motor to run for 30 seconds or so before driving and let it warm up to operating temperature prior to driving it hard. They LOVE to rev and be driven hard, but doing so cold can cause problems with engine seals.

Would I buy the car? it depends on the price and how much sitting he let the car do. If it was an RX8 R3 package, I would probably be all over it as I love the way they look.

Letting the car sit without running is what tends to cause coolant jackets and oil seals to fail prematurely, but take care of the car and it should take care of you. The later model Renesis motors should be good to around 150k miles with no rebuild needed. Maybe longer if taken care of or driven mostly freeway.

Expect to give the car a little more love than average. It is a sports car with 4 seats. Also, most people recommend using thicker than 5w20 oil which is recommended by the manufacturer. A 5w30 tends to treat the Renesis motors well while older motors generally recommend a 10w40 or thicker.

 

[blingo]

A slight problem existed in that early models didn't have a complete PCV from the beginning. This added to fuel dilution from much condensation on internal surfaces and also rich WOT. 2010 vehicles should have more flow through them, but even so short trips and winter cold could still have it collect some water and fuel in oil of course (in case of the twin oil coolers the right one is sometimes shielded with a mouse pad then, but for the intended use...)
When flooded from reparking it may actually be better to tow start instead of endlessly "cranking" it over. Flooding can happen two weeks after reparking and even pulling spark plugs then doesn't necessarily help much.
European 5W-30 cars didn't seem to fare better than US 5W-20 cars. Avoiding VII may be especially rewarding with the rotaries.

 

[dareo]

The swap into an RX-8 is a bit more involved than you think.

And the Renesis is a fine engine; you just have to make the entire ownership of the car a hobby.

It's only about $5k in swap kit parts. Then you only have to spend $19k for a complete LT1 T56 connect and cruise package. Add in the cost of the RX-8 and all the time spent working on it and you might as well order a new LT1 camaro.

I've seen countless "non running" RX-8 for sale over the years for cheap but your right, it won't be worth it to swap, unless you value the hobby aspect of it.

I don't think the Renesis is powerful enough and i know the reliability is dubious. I like the RX-8 as a car but Grandma's Toyota Avalon will blow the doors off one.

 

[aquariuscsm]

The swap into an RX-8 is a bit more involved than you think.

And the Renesis is a fine engine; you just have to make the entire ownership of the car a hobby.

I agree. Keep the Mazda a Mazda. No need to turn it into a Camaro.

 

[Skippy722]

Buy it and swap in an LS or LT V8. The rotary at best is mediocre and at worst it turns the car into art deco.

My boss has a Camaro v6 swapped RX-8, that thing RIPS!

 

[dareo]

My boss has a Camaro v6 swapped RX-8, that thing RIPS!

It doesn't take much to beat the stock power plant. Non turbo rotaries were acceptable in power back in the FC generation. Mostly because it was so well balanced and braked stock. I drove a friends 89 N/A FC to pickup my 1999.5 TDI. The TDI had more torque at 1900 than the FC did at any RPM. The FC was still more fun to throw into a corner!

 

[Skippy722]

It doesn't take much to beat the stock power plant. Non turbo rotaries were acceptable in power back in the FC generation. Mostly because it was so well balanced and braked stock. I drove a friends 89 N/A FC to pickup my 1999.5 TDI. The TDI had more torque at 1900 than the FC did at any RPM. The FC was still more fun to throw into a corner!

My other coworker has a LS swapped RX-7, they both take them to track days. Both of them have tons of work into braking and suspension. Very cool cars. Pop up headlights win though

 

[Cujet]

The idea of adding two stroke oil to an RX8 rotary has merit. Mazda injects a token amount of dirty crankcase oil into the rotor. Many owners choose to add 4 ounces of conventional two stroke oil to a tank of fuel.

To Premix or Not to Premix

Rotary engine premix Idemitsu RX-7 RX-8

rotaryperformance.com

From rotaryperformance.com: Premixing along with a couple additional changes effectively doubles the engine life of every RX-8 engine.

 

[aquariuscsm]

I'v never liked the idea of an engine swap. It completely takes away the heart and soul of the car. What's really impressive is when people take these tiny stock cars and make hellacious power out of them!!

 

[Andrew1972]

how exciting! Don’t pay more for low miles just pay on age and condition. Also a good chance the engine will be junk so as long as comfortable go for it!

 

[2EHA]

These things are hilariously easy to work on. We pulled a motor from a wrecked car in a little under 2 hours, engine was so light 2 people could lift it up out of the car with no effort.

as a second car I don’t see why not.

 

[Gyro Gearloose]

I had one of the first gen models and enjoyed every inch of the 90,000 miles I put on it over the space of 12 years.. By that time though the seals were getting worn and power was down noticeably. And I did mix in an ounce of motor oil for every gallon of gas I put in it trying to extend the seal life.
Never had a warranty claim and only routine maintenance until age caught up with a few components shortly before I sold it.

Trivia: The oil filter was on top of the engine and the engine bay was so open and shallow I could reach the drain plug from the top. Never had to go under the car to change oil, although l did have to run it up on some boards to get it high enough for the drain pan to slide underneath.

 

[wag123]

If it has an automatic transmission, hard pass. The rotary engines on automatic equipped RX8's can fail in only 30k miles, and I have personally seen several of them with failed engines at under 40k miles. This is NOT an engine that should be babied! The rotary engine needs to be revved to keep the carbon from building up and destroying the seals, in other words, drive it like you stole it, but only after the engine is fully warmed-up because driving it hard when it is cold (before the oil is warmed-up) will also damage the engine. A short trip car should also be a hard pass. Average engine life on a properly maintained and driven manual transmission car is also pretty dismal, 80k miles is about all you can expect to get out of one. Use dino oil in it and watch out for failed ignition coils (a common problem) which can also cause engine failures. Mixing TCW3 2-cycle oil with the gas is a good idea. When you go to look at the car make sure that the engine is completely cold (sitting overnight). Hard starting when the engine is cold is the first symptom of a engine that is failing.

 

[blingo]

Hard starting when warm actually is the main symptom of fading compression. Hard starting in the morning would indicate more severe / acute problems. The premix is common practice with enthusiasts but enthusiasts' engines (premixed, revved as if one stole it / kept in short gears / oil fed via adapter...) don't tend to live longer than average Joe's engine unsupported by the milieu. If all coils, wires and plugs always remain up to the task there's still a good chance of gradually worsening warm starts from such 80k on, but from weekend trips with a 27k engine from not the most enthusiastic previous owner there should be many years of normal touring to be had. If it had the catalytic converter replaced recently, that could be an alarm signal.