The picture pretty much says it all. I'm concerned about the copper, lead, and gas dilution results. Can somebody tell me how normal these are? Should I be worried?

S4 N/A, rebuilt about 3500 miles (2 years) ago with used housings

Also this part, "Caution! Is the oil level rising?" That would be a yes...

 

6x higher on the Cu, and almost 7x higher on the Pb?
I'd say you got premature bearing wear...if the "universal averages" are accurate.


-Ted

 

Oh ffs, exactly what I didn't want to hear.

Would the gas dilution cause that?

 

Yep. It drastically thins the oil. Did you ever run 10-30?

 

For a very short time (~500 miles maybe) during cold weather and then I switched back to 20w50. I actually switched back because I was afraid of engine damage.

Since 10w30 was my previous oil change prior to the tested one (20w50), could some of (all?) of the copper/lead be from the residual oil left in the system?

 

Very high copper and lead content but very low molybdenum (only 12% of "universal average" levels) which is a primary friction reducing agent. Coincidence?

 

that would be like, what additives are in the oil, and not the grade

 

Apparently not. I was kinda curious what molybdenum was.

Anyways, what would be causing this? Just the gas dilution?

I'm also assuming that Castrol GTX doesn't contain Boron.

 

uttttttt oh .... we arn't supposed to use 10-30?? *feels stupid*

 

Could you explain this further or point us to a thread?

 

The additive package is what makes a motor oil a motor oil. Without them, any base stock is worthless as a lubricant. The base stock is very important in other ways though. This oils shows abnormally low amounts of one of the main actual antifriction agents in the oil which doesn't look too good.

 

Can you elaborate on that? As in, why is it low? Is my engine going to go boom? Etc.

Thanks ahead of time.

 

This is the first time I have ever seen this for a rotary...interesting to say the least.

Normally, you see this sort of thing for aircraft engines. On the upside for those engines there is a very established baseline since so many samples are sent in.

Maybe you could find a few rotary aviation guys and ask if they sample their oil and get a look at their sheets to see what it looks like.

It would be interesting if a few more people here did this.

You should ask the company that did this if their base line is rotary specific.

Besides, I always though we had more gas in our oil?

James

 

It looks like they're suggesting that you're leaking fuel into your oil, which is causing the oil to thin and bearing wear to increase. It does say on the sheet that the baselines are for a Mazda 1.3L Rotary, so that's taken into account. I can't think of how the gas and the oil would meet though, unless you're getting severe leakdown from leaking injectors, and keeping your oil in too long between oil changes. . .

 

Here a couple of threads from the rx8club forum on blackstone analysis tests. Compare them to yours.

http://www.rx8club.com/showthread.ph...t=oil+analysis

http://www.rx8club.com/showthread.ph...t=oil+analysis

 

10-30 is too thin for hot environments. With lots of heat and fuel contamination, it thins out like water...

 

One of the ones rotarygod linked mentioned gas in the oil. They said it could be due to lots of idling and city driving. Most of my driving is city... hmmm...

This oil had 1500 miles and I had my injectors professionally cleaned about 2 years ago (less than 2000 miles).

 

just drive it till it blows

 

Maybe that's it, but that seems like a substantial amount of gas in your oil.

Ooh, I've got it - how about a faulty fuel pressure regulator?

 

Never tested it... guess I could. I average about 17mpg with 5/6th ports open all the time (yeah yeah, I'll fix it this summer ). That's pretty good for a semi-hilly city.

 

I think you need to stop putting penny's in when you change the oil. That'll lower your copper content

Seems like decent mileage though. I'd imagine the speculations about bearing wear would be accurate. I'm not aware of many other high-wear parts that contain copper in the engine actually

Very interesting test though, where did you have this done? (never heard of it, learn something new everyday)

 

I was just brainstorming, and the only place that the fuel and oil would come together is at the engine, and it would be extra unignited fuel either through the injectors, or through the FPR. If the fpr diaphragm was punched, then the vacuum line could suck fuel through the vacuum hose into the intake. That's all I can think of - unless someone is very creatively sabotaging you by sneaking out to your car and dumping a couple of oz of gas into your oil filler.

 

Just a thought, but could bad oil control rings let more gas into the oil than normal?

 

Actually, that's more likely ^ - if your oil control rings were fine, then extra unburnt fuel from a bad FPR would just blow out with the exhaust.

 

Blackstone Labs. http://www.blackstone-labs.com/

They'll send you a free "kit" to put your sample in. You just send it back with oil (3 oz. or so) and $22.50. A couple days later you get the results.