Let me preface this by making the following 2 disclaimers in the interest of not being torn a new one:

1) I am well aware of the schedule I and II maintenance, replacement and inspection intervals for fluids, coils and plugs.

2) In some of the high miles on original motor threads - 100k and 200k threads (mainly 2004s) - some members have only changed their coils and plugs once, OR, in a couple of instances, not yet.


So here's the question:

Assuming oil/filter changes are done every 3000 miles (with an eye kept on topping off oil levels) and coolant system flush and fills are done every 2 years, if the series I Renesis is purring like a kitten at idle and pulling smooth and hard under WOT (no misfires, predetonation, etc.), is there a consensus that plugs and coils should still be routinely changed absent any indication of issues?

In other words, is there a risk that before a single indication of problems relating to fouled plugs or bad coils first appear, any damage has been done?

I'm not asking because I don't plan on following the schedule II service, but am generally curious because I'm amazed that some members who are credible are rolling on original motors with tons of miles and have changed plugs and coils very infrequently, or in a few cases, not yet.

 

Yet others have megaproblems .

My opinion :

* 3000 mile oil/filter changes are ridiculous
*The leads should be replaced with quality leads as soon as you roll out the dealership door
* The oem plugs last a LONG time but they are a wear item so change them at the recommended intervals (or sooner) or you take a risk .
*The coils last a LONG time if the leads and plugs are kept in good condition - but change them at the recommended interval anyway.

 

+1
Except on the coils ...
And we can chat latter about those

 

There's a reason they call it preventative maintenance. If everyone waited till something broke before replacement there would be alot less cars in motion

 

+1

As long as the coils, plugs, and wires are functioning, they will cause no damage. HOWEVER... I've seen plenty of people run with a misfire, and not even realize it. This is where you can run into big problems.

 

Hey guys, I appreciate those succinct, prompt and helpful responses.

Since the OEM coils and plugs have a tendency to last a long time, are you implying non-OEM replacements have a shorter life span?

Thanks.

 

That depends on the quality/suitability of the part .....

 

I waited till I got a "hesitation" at Wot and then did the plugs/coils. It was at 53k and now at 72k I'm figuring about 100k for new coils....if I keep it that long

 

I've been struggling with that lately. Seems like a little over kill to change the oil that soon, but many people seem to recommend 3000 mile oil/filter changes anyway for rotaries.

I even called Racing Beat to confirm the information they have on their website:

"Oil Change

The Mazda RX-8 Owners Manual indicates that the engine oil and oil filter be changed every six (6) months or every 7500 miles, whichever comes first. Racing Beat supports this recommendation.

Mazda recommends the use of SAE 5W/20 with a quality designation of ILSAC or SL."

As you all know, racing beat is supposed to be an authority in the rotary community for decades, so I find it quite interesting that they seem to support Mazda's oil/filter change intervals when most people here seem to say 3000 miles is the way to go.

I've been doing it every 3000 miles anyway, but it does seem overkill based on my driving conditions

OP: I hear you. Many people seem obsessed with changing the coils and still get engine failures, while others seem to get many trouble free miles without even changing the coils.

I always changed coils and plugs in my vehicles every 30-40K miles anyway, so I think I will follow the same interval with the RX-8.

But apparently there's no guarantee!!!

 

i may be one of those people.
mines (07 mt) at 37k with original plugs, wires & coils.
my only concern is when idle, the rpm niddle slightly dips down (say 800 to 700rpm) and goes back right up to normal position. and when it does, the car slightly vibrates.
this happen when engine's warm every 20 seconds?
i doubt plugs or coils cause when giving gas it runs smooth without any problem.
oh, and the exhaust makes consistent pops like bo bo bo bo.....not loud, need to stick my head right in front of it to hear it.

 

My engine light went on when my coils started to go bad. It took me a week to get it in for service. by then the car was misfiring now and then. The dealer did diagnosis and informed me there were a couple cels. After further testing they told me the coils were bad, the catalytic converter fouled and to rplace the plugs. Compression was fine. I replaced the coils myself after picking it up. The car runs fine now and no cels. I plan on replacing my plugs myself and having the emmisions tested at the DOT.

 

If you are unsure of the maintenance history, just change 'em. Fluid, coil and plugs. That way you "reset" the maintenance history to your timeline. Not alot of $$$ for peace of mind. Yes, rotary likes fresh oil like Lululemon staffer likes fresh kale juice.