Mazda RX8 oil sample nine

[compaddict]

I missed taking a sample on the oil change before this one.
2004 Mazda RX-8

Oil OEM Redline Redline Redline Redline Redline
5w20 5w20 5w20 5w20 5w20 5w20 5w20 5w20 5w20
Oil added 0 0 0 0 0 0 1 0 1
Miles on Oil 1250 1764 1500 1500 3000 4000 6581 4400 6000
Miles on Unit 1250 3014 4520 6067 9166 13221 19802 24201 37,431
Date 12-13-03 12-30-03 02-09-04 03-24-04 06-04-04 08-30-04 02-15-05 06-10-02 12-13-06

Aluminum 9 5 5 10 6 6 7 9 4
Chromium 4 5 6 5 6 7 11 13 24
Iron 30 30 33 29 29 35 50 47 54
Copper 18 22 15 10 7 6 7 6 5
Lead 1 2 0 3 3 5 5 6 8
Tin 0 1 4 0 1 1 1 1 0
Moly 480 471 578 599 586 556 574 750 632
Nickel 1 1 1 1 1 1 2 2 2
Manganese 0 1 1 1 0 0 0 1 0
Silver 0 0 0 0 0 0 0 0 0
Titanium 0 0 0 0 0 0 0 0 0
Potassium 0 2 5 4 3 2 5 1 1
Boron 137 71 37 24 17 8 14 22 12
Silicon 42 28 21 17 15 15 15 17 15
Sodium 8 15 18 20 20 22 20 27 21
Calcium 1724 2421 2565 2841 2906 3394 2698 3160 3101
Magnesium 5 6 7 6 6 6 14 13 10
Phosphorous 850 1015 1084 1077 1091 1222 1183 1419 1326
Zinc 884 1236 1165 1236 1362 1371 1304 1533 1402
Barium 1 1 0 0 0 0 0 0 1

SUS Vis@210C 50.3 50.9 53.4 54.1 54.4 58.5 59.6 62.3 54.4
Flashpoint F 335 325 340 370 395 400 370 440 340
Fuel 1.5% 1.5% 1.3% .5 .5 .5 .5 .5 2.3
Antifreeze 0 0 0 0 0 0 0 0 0
Water 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Insolubles 0.2 0.3 0.4 0.4 0.3 0.2 0.5 0.3 .3

 

[TR3-2001SE]

Look reasonable except for the fuel problem. This is affecting lead,iron and chrominum. No rotory expert but I would think new plugs and injector cleaner would be in order.

 

[uconn1150]

I agree, the fuel was trending down from the beginning and was stable, but has now spiked 4-fold.

 

[compaddict]

I had a piggyback computer that removed fuel from the mix. Piggyback was taken off 10k miles ago.
I am going to have Racing Beat reprogram my OEM computer to do the same thing but better in the future.
Vince

 

[buster]

Chromium/Fe/Pb are all very elevated.

 

[compaddict]

The next oil change will at 3k miles just to keep an eye on it. The bad thing is the RX8 retains 3 quarts of oil every change.
Vince

 

[TeeDub]

Could you give us a brief overview of the metallurgy used in this engine for various components? It would really help in making sense of this data....

TD

 

[buster]

I've seen fuel thin out an oil, but not cause wear metals like this. Somethings up.....another questionable RL UOA.

 

[JAG]

These engines inject motor oil into the chamber specifically to lube the seals, so a lot of oil burning occurs. I know a guy who rigged it up so that the injected oil was 2-stroke oil to minimize the ash created, while the sump still used regular 4-stroke motor oil. That's a great idea. I wouldn't use a high ash oil like Redline in this engine. To keep the fuel-in-oil contamination down, I would probably use a 5W-20 dino oil and change it often instead of using a more expensive synthetic and change it less often. That's just what I'd do. I don't own this type of engine so do as you will.

 

[Ethan]

TeeDub,

Iron is going to be in the apex seals of the engine and I believe the side seals. I think the corner seals are another material altogether, but I could be mistaken. I've always thought that fuel power would be an excellent candidate for this motor as it would assist the lubrication of the seals in this motor. That is why oil is injected into the motor. Should also help control deposits.

Ethan

 

[goodvibes]

Redline might be the right oil here as injection tends to gum up the seals over time and hurts compression. You might want to check if RL is 100% Ester. If not, you may want to find an oil that is. Anything but ester will leave more residue. Fuel power sure won't hurt. Have you tried Denso Iridium power? Bigger spark than the NGK.

 

[gtx510]

Rotaries use funky anti-fouling sparkplugs. They're kinda like 4-post, side discharge plugs.

imho, 5W20 is too thin for a rotary, but Mazda is stuck with Ford's CAFE oil. And the RX-8 needs the mpg help anyhow.

Best set-up would be a separate tank for oil injection and use 2-stroke oil in that. Then run xW30 in the oilpan.
Other than that I'd look for a clean burning (ashless) oil. The new Euro low SAPS oils should work well, German Castrol...

Don't ge afraid to rev that rotary, that's the best way to clean off those carbon deposits. And clean your sparkplugs with a wires brush everytime you change the oil.

www.rotaryengineillustrated.com

 

[Ethan]

You could just run straight up two stroke oil in the fuel tank and disable the oil injection.

 

[Primus]

Here in Europe, Mazda recommends Mazda Dexelia 5W-30 API SL, ACEA A5/B5. The oil is rebadged Elf Evolution SXR 5W-30 that, in its turn, has a couple of cousins under the brand name of Total. Its previous version (ACEA A1/B1) was at a half step from W20 viscosity.

 

[gtx510]

Odd, Mazda (in the US) said no to synthetics in a rotary back in the late 70's?

http://cgi.ebay.com/ebaymotors/ELF-Synthetic-Oil-SXR-5w30-Fuel-Economy_W0QQitemZ20003671887
$57 for 6 liters

www.whnet.com/4x4/oil.html HUGE list of (MB) Euro oils
MB 229.31, 229.5 and 229.51 should all work well. A3/B3 or A3/B4 oils should be thicker than A5/B5 oils.

ACEA info
www.infineum.com/information/ACEA_whatsnew.html
www.infineum.com/information/consumer.html

 

[bulwnkl]

Quote:

---

I've seen fuel thin out an oil, but not cause wear metals like this...

---

Wrong yet again, Buster...

 

[TeeDub]

This is fuel dilution problem, not an oil issue. I'd talk to the dealer and see how common this problem is and what if any fix they have recieved from Mazda Corporate.

Since your powertrain warranty is still in effect, I'd raise H--- about this and have the dealer work on it.

TD

 

[compaddict]

RX8s run pig rich at WOT, like AFRs in the 10.x range. Combine that and mostly city short range driving.. And I think that made my fuel go way up.
Like I said, I'm going to have Racing Beat re-program my PCM to take care of the 10.x AFRs and we will see were it goes from there.
The whole 5w-20 VS 5w-30 thing, I'm going to stick with the 5w-20 because I don't know if the USA PCM is tuned to meter the thicker oil or not.

Vince

 

[gtx510]

But the oil that's injected into the rotor housings should be burnt up. And it doesn't drain back into the pan like on the bores of a piston engine. So why do rotaries always seem to have fuel in the oil? Is it getting by when the engine is cold? They also run quite rich at start-up. Does Mazda still have the ECU rev the engine to 3k to fire off the cat quicker? RB might be able to remove that too? Most FD owners do that.

Does the RX8 have an oil cooler? Oil pan with 'tanks' that don't drain like an FD? So you're only changing about 1/2 the oil?

The oil metering pump will just put out the same amount of oil, but that thicker oil would seal your apex and side seals better and give more protection against wear.

Follow what Mazda rec'ds for the rest of the world, not North America. 5W30 in the Ukraine, I'd run German Castrol (almost a 40wt) or a synthetic xW40 for a Kali summer. Regular 5W30 in the winter.

 

[Bobert]

The Chromium is really climbing. Why not experiment with something else-- maybe a thin 30wt oil? With as much fuel dilution the RX-8 is capable of a 20wt seems too thin.