RX-8 eighth oil sample

[compaddict]

2004 Mazda RX-8

Oil OEM Redline Redline Redline Redline Redline
5w20 5w20 5w20 5w20 5w20 5w20 5w20 5w20
Oil added 0 0 0 0 0 0 1 0
Miles on Oil 1250 1764 1500 1500 3000 4000 6581 4400
Miles on Unit 1250 3014 4520 6067 9166 13221 19802 24201
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

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

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

 

[buster]

Is this car raced? Fe wear is very high. I'd like to really know if it's Fe wear however. Believe it or not, I don't think a lab would flag it though. Unless it's over 150ppm.

 

[unDummy]

But where is the Fe coming from? gears? e-shaft? oilpump? chain?

Excellent rotary UOA history.

Time to try other oils, a magnetic drainplug, an oil filter magnet, or better filtration.

 

[railball]

I would go to Terry with this one too many things to consider before leaving RL.

 

[compaddict]

I might try a magnetic drain plug. This sample was the longest without an added quart.

Vince

 

[buster]

Yeah go with Terry. RL is a strange animal.

 

[TooSlick]

If you leaving three quarts out of seven in the engine, the wear metal concentrations @ T = 0 are going to be about 43% of the previously tested numbers. So you have to take that into consideration and subtract those concentrations from the last data set to get the actual wear rates. Got It???

For example, the previous sample was used for 6580 miles, so it had the highest concentrations yet. You started out with 43% of those 6580 mile totals
@ T=0:

Al, 4 ppm
Cr, 6 ppm
Fe, 20 ppm
Cu, 2 ppm
Pb, 2 ppm
Sn, 1 ppm
Ni, 1 ppm


That's why this particular sample looks worse then the similar 4000 mile run on 8/30/04. The service interval prior to THAT 4000 mile run was only 3000 miles. So the three qts of leftover oil in that instance were pretty clean in terms of wear metal concentrations.

I'd stick to a 5000 mile service interval for 3-4 changes in a row - that will make the math much easier and keep me from getting a headache...

 

[molechaser]

TooSlick has a good point here. Just for grins, I did the math on the two ~4000 mile samples posted here.

The adjusted data are as follows:

code:

---

Sample # 6 8

Miles 4055 4399

'

Al 3 6

Cr 4 8

Fe 23 26

Cu 3 3

Pb 4 4

Sn 1 1

'

ppm/1000 mi

Al 0.8 1.4

Cr 1.1 1.9

Fe 5.6 5.8

Cu 0.7 0.7

Pb 0.9 0.9

Sn 0.1 0.1

---

Makes this interval look much better but there are still slightly high Al and Cr numbers. Worth keeping an eye on if a trend develops.

Question for the Red Line gurus: Is this just a Blackstone anomaly or do the moly, zinc, and phosphorus values seem on the high side for Red Line? Certainly the highest reported in any of these samples by a fair amount.

Molechaser

 

[molechaser]

The viscosity seems on the high side for a 5W-20 oil. Your viscosity runs higher than what I am seeing with 10w30 Castrol Syntec Blend.

For the rotary challenged, there is lots of iron in the rotary engine. The side housings are cast iron as are the rotors. All of the RX-8 used oil analysis are showing fairly high iron.

One other thing that I am seeing is that the 3 qts of oil left after a change means that it takes a few changes for numbers to stabilize when the OCI is changed. Even so, the iron, aluminum, and chromium seem a bit high for this shorter interval

molechaser

 

[compaddict]

TooSlick:
Since you have gone to the trouble of doing the math.. 5k service intervals it is!

Thanks!

Vince