This is a follow up blog to part 1 where the basic workings of the rotary engine were explained. As mentioned there, the engines have gotten a somewhat undeserved reputation for being complex and unreliable. Yes, there are some imperfections in the design but, as explained there are some very simple things you can do to counteract these and ensure that you get a long and healthy life from your Rx8 – naturally when considering whether or not to buy one, these tips should also act as a buyers guide to make sure that you are getting a well-cared for example.

For more general tips on buying a used car you can check out this post here


Mazda Rx 8

What engine oil for the Mazda Rx8?

As mentioned in part 1, oil is hugely important to the smooth and healthy running of an Rx8 – yes they are designed to burn oil, No, they don’t guzzle gallons of it (or shouldn’t anyway!)

Use a mineral oil or mineral based semi-synthetic oil most enthusiasts opt for 10W40 with others using a heavier 20W40 for extra protection under heavy driving. Mineral oil burns cleaner than synthetic meaning less carbon in the engine and, as a result, less wear on the apex seals and longer engine life.

As mineral oil degrades quicker than synthetic oil, you will need to change it more often (about 5l every 5,000kms is recommended) with a new oil filter every second change. It is also highly recommended that you add about 250ml of good quality two-stroke oil to your petrol tank every fill – this provides additional lubrication and cooling and will ensure that your engine stays healthier for longer.

When viewing cars, ask the owner what oil is being used, how often its changed and are they premixing with two-stroke. If they can’t answer these questions, it’s not a good sign and you should probably keep looking!

Mazda Rx 8

Mazda Rx 8 Ignition

Again, in part 1 of the blog, I mentioned the heat generated by the rotary engine, it’s worth noting that when fully opened up to the 9,500rpm redline, the renesis engine is completing 19,000 ignition phases per minute! That’s 316 explosions every second!! That, naturally, creates a hell of a lot of heat. Unfortunately, Mazda decided to place the ignition coils of the Rx8 quite close to the engine block which had an unfortunate outcome. The coils began to fail prematurely from the heat which resulted in poor spark to the engine, in turn leading to unburned fuel stripping some of the lubrication from the combustion chamber, washing into the catalytic converter, melting it and in some cases, ultimately leading to engine failure.

The ignition system is of huge importance to the Rx8 and should not be overlooked. Make sure that, at the very least, genuine Mazda coils are being used (preferably the most recent ‘revision C’ variant) ideally, upgrade to fairly easily available D585 coil set which uses the ignition coils from a Chevy Yukon truck!) these will generally last a lifetime and give you better performance. Whilst not cheap (up to £400 for the full kit including coils, bracket, harness and leads) they are a really worthwhile investment. They do come up for sale second hand from time to time or, if you’re at al mechanically minded you can head over to for advice and links on how to build your own set for around €200.

Spark plugs should be changed at around 20,000kms and there are 4 in total (two leading and two trailing ones) at about €100 for 4, they’re not cheap either but are essential for engine health and performance. Finally, it’s advised to upgrade the ignition leads for thicker magnecor ones which ensure that your coils transfer maximum firepower to your plugs.

Please, please don’t buy cheap Ebay coils leads and plugs no matter how attractively they’re priced – they will almost always fail very quicky, cause you issues and cost you more in the long run!

When viewing a car, ask about the ignition components in detail, what is being used, when they were changed, where they were purchased. If you don’t get good answers or if you draw a blank stare – again, could be best to walk away. If you can, pull the plugs and check their condition – if they’re badly fouled you could be asking for trouble further down the line.

Rust Issues With The Mazda Rx 8

Rx8’s in Ireland and the UK are prone to rust – please make sure you check the sills, wheel arches and around the centre brake light for signs of corrosion. Quite a few cars have had NCT failures as a result of this and repairs can be difficult and costly.

Compression Test Your Rx 8

To have ultimate peace of mind when purchasing an Rx8, the best thing to do is have a compression test carried out, this will give you conclusive proof of the health of the engine. If you’re buying from an enthusiast, chances are they will have had one done and should be able to show you proof of the results. Excellent results would be be readings in the high 8’s or above on both rotors with each face being consistent if you get anything below 7’s, the engine is beginning to struggle and may need care in the future (though it’s not unusual for engines with relatively low numbers to continue on perfectly well for many 1000’s of kilometres)

The engine needs to be tested using a specific rotary tester so head to the forum and see who has one in your area. If you can’t get the compression tested then you need to pay close attention to how the car starts from cold and from hot. It should fire up straight away with no hesitation from cold and should pull strongly through the gears the whole way to the red line – hesitations could be related to failing ignition components, sticking SSV valves (which can be cleaned but this involves a lot of engine parts to come out in order to gain access and is best left to someone with mechanical skills) or something more serious.

Once the engine is nice and hot, turn it off, leave it for 10 minutes and start it up again – if it is sluggish to start it’s not a good sign. Hot starting issues are usually associated with poor or failing compression. Finally, have a look under the car towards the front at the starter motor – Mazda released upgraded versions of these and whilst it’s no bad thing to have one of itself, many owners have used a more powerful starter to overcome slow warm starts thus masking compression issues. If it looks new question the owner on it and ideally get that compression test!

Recalls For Your Mazda Rx 8

There were a few recalls carried out on Rx8’s throughout the years – oil cooler lines can corrode and should have been checked or changed, the airbags should have been changed, there is an impending one for front suspension components on certain 2004 models and others for issues with fuel tank components and airbag wiring harnesses. Get the VIN number and check with mazda to see if these have been carried out. I recently brought my own to a dealership and got the airbag replaced along with a full new set of oil cooler lines and a courtesy car whilst it was being done, all free of charge – not bad for a 13yr old car!

Mazda Rx 8

Niggles with the Mazda Rx 8

Most cars will be between 10 and 14 years old by now and there are some niggles to look out for. The seals on the rear lights can go leading to condensation inside – it can be dried out with a hairdryer and resealed with a new gasket kit or some silicone sealant. The gear lever surround and the rubber boot underneath it can tear and let some gearbox noise into the cabin – you can find replacements from breakers/owners easily enough. The coolant sensor can fail leading to a low level warning light even when the level is full. Many owners have removed the catalytic converter (rotary engines are exempt from emissions testing at the NCT) this has the advantage of making the engine breathe easier and improving performance but can throw an engine warning light. The wiring connectors under the seats can get loose and cause an airbag warning light but it only takes a second to plug them back in firmly and finally, the coolant overflow hose is directly above the power steering connections and can drip down and cause intermittently heavy/light steering – this can be fixed in most cases by a simple clean (power steering is electric so there’s no pump to go wrong)

On the plus side, spare parts are plentiful and cheap and there is a thriving, knowledgeable and really supportive rotary scene in Ireland with a large number of people on hand to help out with advice and tips as well as lending a hand and/or spanner if needed.

Overall, the Rx8 is a fantastic car to drive with a responsive chassis, great free revving engine and performance that is comfortable and quiet inside. With an interior that hasn’t aged and which (in 231bhp 6 speed format) comes with heated leather electric seats, xenon headlights with pop out washers, 6 CD bose sound system and 4 seats, you’ll be hard pushed to find any other car that drives, handles and performs like it. With prices as low as they are now, it’s a perfect time to go out and grab a real bargain – consensus is that the Rx8 is a future classic in the making and good examples should begin to appreciate in value in the next 5 years or so.

You should do yourself a favour and put it on the wishlist – follow the advice above and you’ll be glad you did!           


  • Carlos Guerrero

    So the rx8 passes the emissions test even if you dont have a CAT on it since its exempt?

  • Bareera shahid

    Awesome and lovely article. very informative article.