The thermostats always allow some oil through regardless of temperatures. They just allow more when warmed up.

 

Your oil won't necessarily look "dirty" at 5000 miles, depending on your driving conditions.

https://rotaryperformance.com/collec...ler-thermostat

No, you need those thermostats to open and close at proper oil temps. The lower temp thermostats just open more sooner, but still when the oil is at proper temp. It is important that they regulate the temperature, or else the oil can become excessively cold in winter weather.

Mazda calibrated them to a scaldingly high temperature (220F) for federal emission reasons. A more sensible opening temperature of 165 degrees will help extend the life of the engine. The lower temp oil cooler thermostats are calibrated to open more at 165 degrees, and be fully open by 175 degrees.

 

Stick with FL-22. For the frequency of drains/refill - it is the best bet for rotary engines given I'm not a metallurgist. I've always stuck to OEM for coolant issues because I cannot measure wear and rusting on the inside even though the thermostat readings might be same/better.

If anyone has data and pictures of their interior surfaces using something other than OEM, by all means share.

 

Thanks for all your help. The radiator has just arrived and will be mounted in the next few days. If my current radiator is shot, then there would be a noticeable difference right away.

I'll keep you updated. And thank you again for all your help. For anyone who wants to see pics or videos of the project, they are here. I will add more when the car will be registered :

https://www.rx8club.com/new-member-f...n-ones-264203/

 

Hello!

I have some good news. The cooling issue was solved. It was a faulty radiator. The other radiator that came from the UK might not be as pretty but it does the job.

The issue is that the temps are...stock.

First fan kicks in at low speed at 93C / 200F . Second fan kicks in at low speed at 103c / 217F . Both fans kick in at 106C / 223F.

Compared to the other radiator, at least the temps drop a lot quicker now.

For me, these temps are unacceptable. I want Fan1 at low speed at 80C / 176C. Fan2 at low speed at 85C / 185F and both fans at max when it hits 95C / 203F.

The above might seem a bit low but I have to take into account that this car will be my daily. This includes bumper-to-bumper driving in the city during summer time with the AC on so I'm sure it will get to these temps very easily.

I have decided to contact the people over at Wankelshop for an ECU remap just for the temps. Compared to a fan controller kit, it is cheaper, safer and also adds more benefits like setting max RPM when cold.

Thank you all for your help. Cheers!

 

Yah, those fan trigger temperatures are high for a stock ECU (at least for the USDM, don't know about your market).

They should both turn on high around 207°F.

 

What was wrong with the radiator? My car was running hot too, but it got a lot better after I sealed around the radiator. It didn't fix it, but it certainly reduced the temps.

What year is the car? Only S2s have 3 fan speeds. And they both turn on at the same time.

Low speed - 206F
Middle speed - 213F
High speed - 226F

For S1s, it's just low and middle speed. Trigger temps are the same.

 

That's the weird thing. It does have 3 stages for the fans but my VIN says that the build date is October 2003 so it's one of the earliest production cars.

I think the radiator was just old. I'm not a mechanic so I don't know how to explain it but it didn't leak and it didn't have any flow issues but it just couldn't cool the car. Even when the fans kicked it, the temps would barely drop.

With the "new" radiator, the temps start dropping from the moment the fans turn on.

To be honest, the cooling system on this car is stupid. They should have made 2 smaller radiators each with its own fan and 2 smaller water pumps, one for each rotor.

The reason Rotor2 is the one that fails first is because Rotor1 gets cool water from the radiator and Rotor2 gets the warm water from Rotor1, because the cooling system is shared by both rotors, hence the pressure differences between the chambers and thus, faster engine failure etc.

Either way, stock temps are way too hot for my taste so I'll have the stock ECU edited for lower fan speeds.

I'll keep you guys updated as you've all been very supportive with advice along the way. Thank you!

 

UzY3L ,radiators can build up rust inside over many years and with aging coolant, and it greatly reduces their cooling ability. Nothing unusual with a 2003 radiator being bad after 14 years.

 

That was...wow. Forgot that metal rusts ) Was expecting to see rust pouring out from the thing but didn't see it so I thought it wasn't that. But yeah, you're right. Thank you!

Was thinking now of mounting a simple On/Off switch to the Cooling Fan 1 relay and put the switch in the cabin.

From what I've read, if I pull the relay out and jump the connections, both fans will power on at low speed and this will not interfere with the ECU setting the fans to high speed depending on the temp.

So instead of just jumping the connection, I'll put a simple switch in the cabin so I can start the fans at low speed when I want and let the car turn them on high when things get too hot.

Is this doable?

 

Yes, and there are ECU software mods, and lower temp fan switch kits that will turn both fans on sooner also.

Here is one such fan relay switch kit:
https://rotaryperformance.com/collec...-fan-relay-kit

 

The radiator could also have been dirty on the outside (in addition to the inside). Radiator fins need to be cleaned every 10 years at most.

Considering how inexpensive OEM type radiators are these days, it is often better to simply replace, since cleaning requires almost as much work, if not more. When I refreshed the cooling system in my mother's 2003 Camry a few months ago, a new Denso radiator was $50 shipped, so I just replaced it, since I was going to be in there anyway.

 

update: sorry for the late reply. It's been a hell of a last few months.

I went with the wankelshop.eu ECU mod for the fans. Way, way better temps, no more overheating. Engine locked-up though. Culprit: Castrol A3/B4 semi-synthetic engine oil.

I'm no mechanic, all I know about this subject is what I've learned from the car itself. I thought it was weird that after 4,000Km / 2,500miles the dip stick was milky and the oil inside still had the same colour as the one in the bottle. Lesson learned.

Dropping a new engine inside in the coming weeks.

 

How do you know it was the engine oil?

Milky dipstick isn't out of the ordinary.

Are you saying that the oil coming out of the engine after 2500 miles looked as clean as new? That's... highly improbable.

 

Improbable, yes. Especially since I checked it like a maniac. But yeah, that's what happened: it was milky at the handle but crystal clear at the tip.

Basically, the oil wasn't circulating inside the engine. It was milky because I lost my engine plate / shield and water was being sprayed everywhere inside the engine bay every time it rained.

As for the engine not locking up earlier: I premixed heavily. 700 to 1000ml (23 to 33 oz) of TC-W3 oil (Castrol Outboard 2T) on each fill-up. That's what saved my bacon.

This is just a theory based on my limited knowledge of the engine and mechanics in general. I'm in no position to disassemble the locked engine to find the real culprit. So a direct swap is the way I am heading.

 

Are you actually suggesting a type of oil locked your engine? Impossible. Lack of oil or other mechanical problem, yes, but type of oil, no.

These engines are not picky about what kind of oil you use in a short run (3000 miles or less). As long as there is oil, it doesn't much matter. Castrol Edge is just fine.

Many of us have run synthetic oil for years. I have used Mobil 1 full synthetic for the past 5 years (along with whatever random oil happened to be on the shelf in my garage).

Milky oil on the dipstick is perfectly normal for these cars--especially if they are frequently driven shorter distances. It happens all the time and is nothing to worry about.

Perfectly clean oil in the pan is cause for concern. That can't happen after 2500 miles, unless there is a serious mechanical problem. That oil wasn't circulating, and that is what killed your engine.

 

Premix saved your bearings to which it has no access? Come back to earth man.

 

Premix and injected oil do not lubricate bearings. Only apex seals (and to a lesser degree side seals).

If you drain and refill your oil the same way as most normal rotards, it will quickly mix with the old oil in the coolers and residue everywhere else. The only way for oil in your engine to still appear pristine after 2500 miles is if your oil pump had failed and oil wasn't circulating. When you do an oil change, you only get about 1/2 the oil out of the system (unless you go crazy by dropping the pan and emptying the coil coolers and lines).

Furthermore, the OEM dipstick has a cap and o-rings to seal itself inside the dipstick tube. Unless your dipstick was damaged or modified, no amount of water spray in the engine bay (short of swamping it in a flood) should impact what you see on the dipstick.

 

@Steve Dallas: Thank you for the information. As I've said before, I'm no mechanic and most of what I know is from what I've read and from talking to people, exclusively on the RX8.

That being said, from the data sheet and my poor math, Castrol A3/B4 was about 5% away from Miller's Trident. I couldn't get Miller's Trident in my country (not at a reasonable price anyway) so the next best thing was the Castrol oil.

Rotaries not being picky about oil is a first for me as everyone I've talked to locally nearly stabbed me when I mentioned I wasn't using the Mazda Dexelia oil (which as far as I know, is Total Quarts 9000).

Oil contamination? Mixed with water? I don't know but we can all agree on one thing: oil not circulating is what locked up the engine.

I will probably get the courage and the time to disassemble that engine someday but for now, my priority is swapping the engine so the car runs.

@Loki: I wouldn't know, honestly. I thought premix saved my bacon since I was racing an Alfa 159 that day. This is the story: I was driving from Focsani to Bucharest on E85. The Alfa 159 came behind me. Flashed his high-beams. I downshifted and hit the pedal. The engine seemed odd, as in the higher the revs, the less power I got. The Alfa 159 won, by half a car (I did take the next bend at 180Km/h / 111MPH, he slowed it down to 80KM/h / 50MPH). Race over, I got to Bucharest and parked the car. Went up to my apartment to grab my work bag, jumped in the car and turned the key. The engine turned exactly two times, then on the third time, a loud mechanical clack (like someone throwing a metal rod into moving machinery) was heard and smoke started coming from under the hood. The smoke was from the battery leads which was normal, since the starter motor was pulling power like crazy to try and turn a seized engine. No matter what I did, even pulling the car with another car and dumping the clutch at 50KM/h / 30MPH helped with the seized engine.

@NotAPreppie: Thank you for the info! The way I drained my oil in the car was a bit overboard. I didn't wanna drain the oil coolers so I drained the oil pan of all of its content, filled up with oil, ran the car at idle for 20min, drained the pan again, filled it again and done. All in all, about 8L / 270oz wen into the car.

The oil dipstick was milky from inside the pipe / passage leading to the oil pan, not from outside. I thought water had seeped inside the dip stick pipe but now I'm not excluding the fact that it might have been engine coolant. These are with the eyes of a novice so take it with a grain of salt. As I've said above, I'm no mechanic so I'm just working with what I have and what I think the logical explanation would be.

 

I've run Castrol GTX, Royal Purple, AMSOil, Mobil 1, Shell Rotella T6, and a few others. The engine doesn't care as long as it lubricates well and you change it regularly. Rotaries used to have one or two oil seals that weren't compatible with synthetic oils but this has changed.

If your engine seized it had nothing to do with the type of oil you used.

Water is a normal product of combustion. It's also normal for some of it to leak past the various seals into the crank case. Since the dipstick tube protrudes from the engine several inches, it stays cooler and cools down faster than the rest of the engine. As a result, the water vapor from engine will condense there. It's normal.

 

^I thought the culprit was the oil since it was still clear on the dipstick even after the engine seized but as discussed above, some other mechanical fault must have been the cause since the oil wasn't circulating inside the engine. Now that you've mentioned it, it does make perfect sense.

Thank you for taking the time to explain, I really appreciate it