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Oil changes and plugs/coils changes - miles driven vs. elapsed time?
I finally bought an RX8 in November (2005 MT, 52k miles) and couldn't be happier with it so far. Only thing that's gone wrong is the glove box handle snapped off the first time I tried to open it, lol.
My question is: I know it's super important to stay on top of oil changes given the way these engines work. The most common recommendation I hear is every 3 months or 3,000 miles. But I've found I'm coming nowhere near that - so far I've driven it less than 1,000 miles in the past 3 months, maybe less than 500. Should the oil still be changed based on elapsed time, or is there really no point yet if it's been driven that little.
I've also seen it recommended, on average, to change the coils and plugs about every 2 years or 20k miles, but again, I am clearly going to fall way short of that in 24 months. So same question, do you change them anyway at 24 months, or is it just a waste of time and money?
Previous owner changed both the oil and plugs/coils shortly before selling me the car, so everything is still pretty recent. Here's a crappy picture of the car, if it interests you:
I'm in a similar boat, only put around 1.5k miles my first year on the 8 and my other summer car. It's best to go by a time-based schedule for low mileage since oil naturally degrades / absorbs moisture over time. I typically change the oil right before they get garaged so things are fresh for the new season. For the RX you could argue for doing atleast 2x oil changes regardless of mileage to ensure you're getting all of the leftover oil within the oil coolers (I think there's still around ~2 qts in there after a typical oil change).
As for the coils, I expect them to degrade through use rather than environmental conditions. My plan is to go by mileage (change coils within ~20k miles if using OEM late revisions) or a 4-5 year time span. Whichever comes first.
Just my perspective. I'll let others chime in with their opinions.
I change the oil in my RX-8's once per year or every 3000 miles, whichever comes first. Typically I change the oil by time over mileage as I don't drive my 8's very often. I keep the same schedule for my RX-7's as well.
As for the coils and spark plugs, I check the plugs twice per year and evaluate them at those intervals. Usually I replace the plugs every other year. I have the BHR coil set so I haven't had to mess with replacing coils since I've installed the set.
I don't agree that oil "naturally degrades" in a time frame like 6 months or even a year. I'd definitely change yearly at a minimum like Mazdaverx7 suggested but if over 6 months you'd driven 1,000 miles I see no need to change the oil. As for moisture, I'm assuming that when you do run the car it's for a decent amount of miles at a time, which should eliminate moisture with the heat of the engine.
I'm changing at 3,000 miles, have been putting around 6,000 miles/year on it. I'm planning to change the coils and plugs in the next few months, have put around 12,000 miles on since buying it but not sure how many miles prior the coils were done, I think no more than a few thousand before I bought it but would rather be safe.
Coils don't have an age, only mileage. They're not bread. You can also upgrade to BHR or similar coils that don't need such frequent replacement.
Oil, it depends a little bit on your climate and choice of oil. If you're on regular, 3000 miles is fine, even if it takes a year. 3-month is... no. No oil outside of racing needs changing in 3 months. If you're on synth, you can go to 5000miles or higher, if you do used oil analyses and observe the results.
Just make sure it's topped up properly since the engine consumes some.
Most folks appear to stick with cheaper regular oil and change at 3k, rather than change to more expensive synth, but it's the not only recipe.
I also forgot to mention, I recommend replacing the coolant every two years. A drain and fill is all you need. The rotary engine is sensitive to coolant and having fresh coolant is the best way to go. This helps prevent corrosion inside of the engine, which can lead to coolant seal failure. I personally use Mazda FL22 coolant.
I also forgot to mention, I recommend replacing the coolant every two years. A drain and fill is all you need. The rotary engine is sensitive to coolant and having fresh coolant is the best way to go. This helps prevent corrosion inside of the engine, which can lead to coolant seal failure. I personally use Mazda FL22 coolant.
That's on my list too, already have the FL22 to do it. This is one of those cases where I have a winter maintenance list and back in November it seems like there is so much time to get it done, now it's mid February and it barely crosses my mind to get to it. I've got to move it up on my to-do list.
02-10-2022, 08:40 PM
