The Engine is Designed to Burn Oil
One of THE MOST pervasive complaints about the RX-8 is how it burns oil. Everything from neighbors to arm chair racers to magazine editors like to rave and complain about how much oil the RX-8 burns.
Well, it's true. The RX-8 does burn oil. However, this isn't actually a problem, and no, we haven't deluded ourselfs into believing that some oil burning is "ok".
The RX-8 burns oil intentionally. After all, the engine seals are completely inside the combustion chamber! The only way to to lubricate the seals inside the combustion chamber is to inject oil (or have oil in the fuel, called premix). This oil then gets burned under combustion, so it has to keep oiling, and oil keeps burning.
On average, you should see about a quart of oil burned every 1,000 miles. If you aren't burning anywhere close to this, something is wrong. If you are burning way less, you aren't getting enough oil injected, and your engine doesn't have much chance of lasting long. If you are burning way more, then either you intentionally increased the oil injection and it isn't an issue (1 qt every 500-900 miles), or you have an oil control ring failure, and oil is leaking into the housing (1 quart every 200-400 miles), or have a severe vacuum problem where the engine is actively sucking oil into the intake. An oil control ring failure will require an engine rebuild to fix, although it doesn't require an immediate fix. You will have more oil smoke, you will burn oil faster, you will likely have greater carbon buildup, your plugs will get fouled faster so your coils won't last as long, and your cat will clog faster, but it won't cause additional internal engine damage. The biggest danger is that the rate of oil consumption will be so high that you have a greater risk of running it too low on oil and damaging the e-shaft bearings.
Keep the oil filled above the 1/2 full mark, letting the oil light come on means you are already critically low. Don't overfill though, since overfilled oil spills into the intake and gums up your intake valving, and can easily cause costly repairs. It is also recommended that you use a long necked funnel when you add oil to prevent oil from going down the vacuum line instead of into the engine.
+ Another point to consider...
Another point to consider though, is that nearly all performance cars out there burn some oil. Most trucks do, many commuter cars do.
- Toyota considers burning 1 quart every 1,000 miles within acceptable burn rates.
- Ford considers burning 1 quart every 1,000 miles within acceptable burn rates.
- BMW considers burning 1 quart every 1,000 miles is actually fairly good.
- Porsche considers burning 1 quart every 1,000 miles within acceptable burn rates.
Do a search for any car you want and "excessive oil consumption". Read the stories people have, and when a dealer has told them that the oil burn rate they are seeing is "completely acceptable."
Time and time and time against you will see that 1 quart every 1,000 miles is pretty damn common! But, for some reason, these engines that aren't supposed to be burning oil don't get hammered for burning it (probably because people just don't notice, thanks to a large oil pan), and the RX-8 gets hammered for intentional oil injection by everyone in sight.