Mazda RX-8 Buyer's Guide

[Editor's note: This article originally appeared in the April 2011 issue of Grassroots Motorsports, back when the RX-8 was still in production]

Mazda’s association with the rotary engine dates back half a century. In fact, while many other marques made earlier attempts to popularize this revolutionary engine, only Mazda achieved real commercial success with it. And while the rotary has …

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80,000 miles.

Great car, but...  80,000 miles...

I am still just a bit amazed.  Mazda HAD to know the engines would not last.

They went from one of the most reliable engines made (if you feed it oil and not boost), to one of the least.

I am guessing it was a bit of a sunk cost thing.  They has already gone that far.  Just go with it and hope for the best(!) Bigger 13B style motor = really bad mpg.  Turbo = not super long life either (but maybe longer than the Renesis?).  Of course, they spent all the money on the Renesis, not a turbo.

In reply to aircooled :

Mazda made certain choices that made further choices forced upon them by Ford into a dire mix.

Mazda reduced oil pressure in order to reduce parasitic losses and placed the bottom of the oil coolers low enough that some oil wouldn't drain back during oil changes without either removing the thermostats or jacking up the front of the car.

Ford mandated 5W-20, for all climates and use cases, and also mandated longer recommended oil change intervals, both in North America, as opposed to the rest of the world.

The Series 2 walked back the oil pressure reduction, which helps; but the only full solution to longevity is to ignore Ford's oil viscosity & interval changes imposed on North American consumers. A 3000 mile oil change interval and a climate appropriate viscosity addresses a great deal of troubles.

For reference, I was at 97K miles before a coolant bottle rupture killed the seals on the  original engine, necessitating a rebuild. That was at least 7 years after a 245F overheat due to a malfunctioning radiator fan motor; but that event was approximately 6 months after I'd switched to Evans Waterless coolant (the same as OEM for Koenigsegg) so insead of immediately needing a rebuild, I got 13 years out of the original engine.

Thanks for the reply.  I figured someone had to have some info on this.  A bit too late for friend that bought a Series 1 new though (1 original and 1 warrantee motor before retired, 120k and 80k miles I think).  He is in a warm climate (SoCal), so the oil viscosity compromise probably had a big affect.

Any guesses on how many miles could be expected if you did all of the above?

aircooled said:

80,000 miles.

Great car, but...  80,000 miles...

In a world of 1 to 10, the vast majority are between 3 and 7, yet we tend to talk to each other like we are either 1 or 10

I was the 7th owner on mine and got 74k, looked like the motor had been opened up before too. 

lovely car just wish it had a wankel instead of a renesis in it

220mile tank for commuting wasn't great either

now its just yard art...

and ford berkeleying things up because of management and budget stuff? not surprised. 

aircooled said:

Thanks for the reply.  I figured someone had to have some info on this.  A bit too late for friend that bought a Series 1 new though (1 original and 1 warrantee motor before retired, 120k and 80k miles I think).  He is in a warm climate (SoCal), so the oil viscosity compromise probably had a big affect.

Any guesses on how many miles could be expected if you did all of the above?

In a world of 1 to 10, the vast majority are between 3 and 7, yet we tend to talk to each other like we are either 1 or 10

The original blew at 87 and the re-built made it to 157 for a total of 244.  The mechanics at Mazda let me know that I had the highest mileage re-built engine they could remember seeing so consider that an outlier.

I averaged about 21.5 mpg with an 85% freeway commute which is outstanding given 236 hp and 3,050 Lbs...my FB gets 17.5 mpg with 100 hp and 2,350 Lbs because it's carbed and has a three speed auto.

Loved, loved, loved that car...no problem driving at 9/10 all day without scaring yourself.

fidelity101 said:

lovely car just wish it had a wankel instead of a renesis in it

Uhhhh... it is a Wankel.

My 2009 is still going strong on almost every original part!  it's still only at 17k miles though.   I figure the amount i drive it (basically only autox events) i'll wear it out in 2055 or so.  Tons of parts are probably going to age out long before they wear out.

This low mile 2007 sold for $25,500!

https://bringatrailer.com/listing/2007-mazda-rx-8-4/

If I had the $$$ --->

Ex-SpeedSource/Mazda Lola B12/80 IMSA Prototype Race Car Roller for sale on BaT Auctions - closed on February 14, 2022 (Lot #65,753) | Bring a Trailer

$ 61,000 for this 1993 stunner!

https://carsandbids.com/auctions/r46PgW4x/1993-mazda-rx7?utm_source=transactional&utm_medium=email&utm_campaign=button

I guess I am going to hang onto my 2011 6K RX-8 and drive the other two I have. 

In reply to Rufledt :

That's the way I see it. My buddy begged me to sell him my 2004 mica red with 113K ($ 4300) and he drove it to work with the low compression for another 30K and then sold it for $3800! 

The owner's manual for Australia states the for temps like FL to use 50 weight oil! RX-8 forever! 

This just popped up on my email.

I love these cars as an awesome cruiser that can do wicked donuts.  Mine is getting repowered to be reliable.

Randy likes them with a Chevy motor, and not the LSX...

I love my RX-8 and it's been nothing but reliable for me but...........

fanfoy said:

I love my RX-8 and it's been nothing but reliable for me but...........

Nah, the MX-6 would have been FWD and built on the Mazda 6 platform.

An RX-8 platform with a V6 could have been an MX-8.

Pete. (l33t FS) said:

fidelity101 said:

lovely car just wish it had a wankel instead of a renesis in it

Uhhhh... it is a Wankel.

semantics I say! 

My question is on the V6 conversion - how much of the original suspension did they keep? What did the do with the multi-link rear? Can someone add contact info?

f1carguy said:

My question is on the V6 conversion - how much of the original suspension did they keep? What did the do with the multi-link rear? Can someone add contact info?

I don't know for certain, but it's probably the kit from V8 Roadsters, and is likely an outgrowth of the NC Miata kit they make (NC is basically a shortened RX8).  Their kits usually have all original suspension geometry, but use a tubular subframe to fit the GM motor mounts.

In reply to f1carguy :

They kept it all.  Keisler Automation

In reply to f1carguy :

I don't see why 300hp is breaking an 8" ring gear the rear end on those is pretty stout. seems like a lot of extra work to get nowhere unless they are chasing specific ratios. 

fidelity101 said:

In reply to f1carguy :

I don't see why 300hp is breaking an 8" ring gear the rear end on those is pretty stout. seems like a lot of extra work to get nowhere unless they are chasing specific ratios. 

You kinda need to with either the stock transmission or most any other Trans with the 4.xx rear-end ratio.

This is why I chose the t5 wc out of a v6 camaro.  Stupid high 5th gear that let's the car cruise at a normal rpm.

In reply to wvumtnbkr :

3.90/4.10/4.30/4.444/4.78/5.12 are all readily available for that diff. 

Apparently, some magazine did a test of some LFX swapped Mazdas...

fidelity101 said:

In reply to wvumtnbkr :

3.90/4.10/4.30/4.444/4.78/5.12 are all readily available for that diff. 

Source? I know it has the same diff like the old FD Rx-7, but those different ratios were getting hard to find the last time I checked.

In reply to fanfoy :

its the same as the FD diff so you can still buy those new and this is common with other models too, its the 2nd gen that is the issue with the long pinion the 1st and 3rd have options. 

4.30/4.444/4.778 are Rx8 ratios which you can get from mazda today. 

the FD 3.90/4.10s I think were recently discontinued by mazda but they are around if you look a bit. 

5.12 is rare and I THINK is a mazda competition part# and may not be available new anymore. 

https://mazdatrix.com/vehicle-year/2010/?product_cat=sets