At idle, these engines “stutter.” This is normal. There is just enough overlap between the intake and exhaust sequence to allow a small amount of the intake charge to exit via the exhaust before it can be cycled through ther engine, causing the engine to idle slightly rough. This characteristic has been remedied on the RX8 engine, but all RX7s exhibit this trait.…
Check the oil level every time you fill up with fuel. You’ll find that every 3rd fill-up or so that it is necessary to add about 1/2 a quart of oil. THIS IS NORMAL. The rotary engine utilizes a metering system that draws a small amount of oil out of the oil pan and then feeds it into the engine with the air/fuel mixture to lubricate the apex seals. This oil is not retrieved but is burned with the air/fuel mix and then expelled out the exhaust.
However, just because the oil is replenished in this manner does not mean that you can get away with never changing the oil. In fact, it is wise to change the oil and oil filter every 3000 to 5000 miles (5000 to 8000 km) at the very least. Spring for the extra couple of bucks for a decent oil filter too. Purolator, AC Delco and Wix are good filters. The cheaper ones by Fram and Champion will usually do the job, but have been known to fail and allow bits of cardboard and glue to float around in engines and plug vital oil passages. Engines have failed because of this. True, the odds of you getting one that’s this bad are less than one in 20 but why chance it?
Oil grade and type:
Mazda’s owners’ manual recommends 20W50 non-synthetic multigrade, but unless you live in an area where the outside air temps rarely drop below 70F it’s best to use 10W30. If you live in places where the winter temps go below 0F you may want to go with 5W30 during those months.
There is an ongoing debate over whether synthetic oil should or should not be used in a rotary engine. One side of the argument says that synthetic doesn’t burn as clean when ingested by the engine via the oil metering system and should therefore never be used, while the other side claims that newer synthetics are ok and provide better protection. If you are running pre-mix (pre-mix = small amount of 2-cycle oil mixed with fuel, accompanied by removing the metering system) this argument becomes a moot point since the apex seals are no longer being lubed by engine oil from the pan. Otherwise, the non-synthetic engine oil does an excellent job and costs about 1/3rd as much as synthetic. That’s what I use.
Low-cost Engine Longevity
I know I lost a few of you with …
One word on overheating these engines – DON’T. Say you’re motoring down the highway and a rad hose bursts. or a heater hose springs a leak. Or the rad packs it in. What ever, your temperature guage is creeping past 1/2 the guage’s span. If you’re driving any other car you may be able to limp the extra 5 minutes to a service station without doing any damage, or you may warp the cylinder head and then have to fork over for the repair bill of $1000 or so.
But if you’re driving a rotary-powered car you need to shut the engine down NOW. Call a tow truck. Or hitch-hike into town for a new hose and a jug of water. If you try to drive it to the station the engine will get you there, no problem. But the over-heating will have warped the rotor housings, causing the water jacket o-rings to fail. This may not become evident immediately in fact, it may even take months. But the only fix is an engine rebuild to the tune of at least $2500. This is one of very few disadvantages of these engines, weak torque at low RPM and slightly higher fuel consumption per horsepower being the others. Otherwise, rotaries are superior to “boingers,” ie: piston engines.…
Use only the recommended four-electrode type plugs made by NGK. There are no substitutes, regardless of what the rookie at Napa, Canadian tire or most other retail auto parts suppliers would have you believe. The ones you need are the NGK BR8EQ14 (1st gen cars) or combination of BR8EQ or BR7EQ or BR9EQ depending on which generation, turbo or non-turbo, etc. you have.…