I have been reading the threads on oil as most of you have, and decided to try to gather any facts that I can on my own engine. One way I am doing this is having oil analysis done on my oil. I just got the results of my first test (third oil change on car).

Some info on the car. It is a 2007 RX-8. I did my first oil change at roughly 5000 miles, my second around 10k and this third one at about 14,500.

I switched to 5W-30 at my first change. On this third change I decided to switch to 10W-40 and reduce my change intervals to about 3000 miles. Depending on results I see will determine if I stick with this oil or try something else.

I am using Havoline oil.


Also I do a techron treatment in my gas before each oil change and premix 4 ounces each tank of gas.


I have decided to post my results for each sample. I hope this will be interesting to other owners.

Here are the comments from the lab on this first sample:

The fuel injector cleaner might be the reason that the flash point read a little
low. Any contaminant can cause a low flash point, though usually that contaminant turns out to be fuel. It doesn't really matter--the flash point was still reasonable. The contaminant lowered the viscosity a little, so this oil ended being a 20W oil. Universal averages show normal wear levels after a ~2,700 mile oil run. This oil
was run longer, so we expected to see iron read a little high. All other metals matched up well and that's a good sign.

 

Okay, I'm using Havoline dino juice, too (I've read nothing but goodness about Havoline), and am glad you posted this.

So, this is an analysis after the 3rd change, and you ran it for 4,500 miles on the third change?

Why the switch from 5W-30 to 40 weight? And have you noticed any differences since?

Thanks.

 

You definitely need to stick with at least 3000 mile OCIs as your Iron and Chromium wear metals are reading higher than they should - 5000 miles is too long IMHO since we have partial oil changes. I am currently doing 2500 mile OCIs.

Part of this increased wear is due to high fuel dilution (1.3%, I know it says less that 2% is OK, but that is just not true, anything over 1% is bad) - which lowers the viscosity of the oil and reduces the anti-wear effectiveness of the oil.

I also agree with use of an xW30 oil, possibly even an xW40 in the hot part of the summer.

For the rotary, it is much more important to change the oil very often as there is nothing you can do to stop the fuel dilution caused by the rich fuel mixture - except to change it often to get it out.

I think a short OCI is more important than the use of synthetics, although if you can afford it, both are beneficial for a long engine life.

Also, these Oil Analysis will not tell you anything about the Apex and Side Seal wear as these particles are blown out the exhaust - you should continue to premix as well to supplement the OMP oil - I recommend MMO as a good "one stop" additional Lube and Cleaner or you could se Idemitsu Rotary Premix, FP Plus, Lucas UCL, to add some lubricity and cleaning that is much needed.

Hope this helps.

 

Thanks convert. This is quite helpful. You might even send the lab a quart of virgin Havoline 10W40 if you can afford it, for comparison sake.

Seal.

 

so the 5w20 oil isnt good fo rmy car to be using huh? i have a 2007 Mt alos. i have done 4 oil changes now and at 21,000 miles. (mainly high way miles) i use castrol oil. i should swith to 20w40 was what i was told from else where on here, i live in florida and we have some hot humidity days... thicker oil would be better?

 

You can always reflash your PCM with an accessport to lean it out some It would be helpful if there was a way to see the quantity of oil being metered and the current flash he's on to better grasp gas sealing vs. fuel/lubricant interaction.

 

Yes this is for third change.

The change is due to two reasons. One I want heavier weight in hopes to get some added protection. Second I found a Havoline fact sheet and they actually use better antiwear additives in their 10w40 and 20w50 compared to all their other oils. They use more zinc and phosphorus which I read would help with wear. Is this true? I don't know yet but hoping these tests will tell me.

 

Yep next sample is 3000 for sure. I agree I hated the fuel amount in there, but at the same time I didn't run the engine enough before the sample was taken so that may be a bit higher than it should have been.

I am hoping the 10w40 will keep its viscosity better, and as I stated with Havoline at least they use better additives with their heavier oils, or so they claim. The next test result should show this.

 

Also as a side note. A friend of mine just ran a sample that was about 3900 miles. His engine has about 5,000 miles more than mine. He is using 10w30 Castrol. I would post his results, but don't want to without his permission.

His wear was a bit better than mine in every category. Not sure if this was due to a slightly more worn in engine or the oil.

His 10w30 was down on viscosity. Not quite as much as mine but close. And Castrol doesn't seem to use hardly any Moly (his was a 7 where mine was 204) in their 10w30 and about the same zinc and phosphorus as the Havoline 5w30 that I had tested.

Just more info for you all.

 

So long as your wear numbers are reasonable, comparing your wear numbers to your friend's is probably irrelevant. There are many variables which effect the results, including the repeatability of the test itself (some variance in measurements will occur with the same sample, for example).

Assuming all variables are held reasonably constant (how you drive, temps, engine condition, etc.) wear metals vary almost linearly with miles on the oil. Iron (Fe) at 30ppm in 5k miles will reduce to 18ppm at 3k miles, when ALL the oil in your car has been in there 3k miles (we get approx 4.5 qts of the 7 out per oil change).

Based upon the report you received, the lab has no aggegate statistics (i.e. your results equal the averages identically, indicating they have no stats for you to compare against). This means it's hard to interpret your results. Compared to a piston engine, your chrome and iron are a bit high, I don't think alarmingly though even with the fact you added 2 qts of oil (kind of offsets the 2-3 you didn't get out on the previous change). Comparing to a piston engine though (they vary a lot amongst theirselves) is also mostly irrelevant. The piston engine vs. rotary are simply too different for such comparisons.

And what Jax said. Change it in 3k. These rotaries apparently dump soot along with gasoline in the oil. I'm guessing that stuff is pretty abrasive. I'm not sure if LC20 offsets that any (since they claim to chemically combine carbon soot with their LC20 formula to produce something beneficial and lubricative).

 

You already added to your statement, but yes, the main reason I'm using Havoline is that it has more moly than nearly any other oil - as well as a great additive package in general.

Some people dismiss the importance of moly-loaded oil, while others swear by it.

Like every other issue in the automotive arena, I guess...

 

There are reasons for that, mainly that Molybdenum isn't just Molybdenum, it is Molybdenum dithiophosphate usually. Also, in more recent years there have been more in-depth studies on the effects of Molybdenum compounds such as MoDTP and MoDTC, here's a little quote:

"Further, lubricating oils containing organomolybdenum compounds, such as MoDTP or MoDTC, have a problem of high coefficient of friction at an early stage, i.e., at the stage of running-in. The additive to the lubricating oil is absorbed on the surface of the metal to form a boundary lubrication film which serves to reduce a boundary friction. A relatively substantial amount of time is taken for the organomolybdenum compounds to be absorbed on the surface of the metal to develop the effect of reducing the friction. When lubricating oil compositions containing the organomolybdenum compounds are used as an engine oil, the effect of reducing the friction develops after running a distance of 2000 to 3000 km, although this depends upon the running conditions of automobiles. However, after the above-described running, the time for the development of the effect of reducing the friction often overlaps with the time for the replacement of the engine oil. In such a case, an increase in the amount of addition of MoDTP or MoDTC does not lead to the development of the effect of reducing the friction at an earlier stage and rather increases the copper corrosiveness."

 

Just some more info. The numbers I was talking about with my friend involved another RX-8 so I thought the numbers might help a little bit in that they are the same car with just a bit more mileage, but obviously not the same driver.

Also the last column to the right for the first chart is supposed to be averages for RX-8s. I believe that is how you can tell you are doing against like cars just to let people know.

The whole Moly thing does seem controversial. I am going to stick for Havoline for a few more changes if I don't see numbers similar to my friend's I will switch to Castrol which doesn't seem to use much Moly and see if I see a drastic decrease.

For me I don't want to make a conclusion until I see some decent evidence like a drastic (percentage wise) increase or decrease of a number.

 

It's not controversial at all, it's a great marketing tool and has legitamite use in some roles.
While I greatly appreciate that you're making this effort, the problem is that the conditions that the oil is operating under is constantly changing and not being recorded precisely. Driving distances, ambient air temperature, ambient air humidity, driving style (load/rpm), fuel composition being used, current PCM flash, spark plug condition... the list goes on and on of variables that could have effect on the numbers in the chart. The things that aren't being looked at are even more important IMO. Bearing wear, deposit formation, precise flow and temperature at certain points in the lubrication circuit along with component temperatures, etc.

If you have access to a lab that can run API SL or SJ full or partial test sequences on oil's you give them, it would help us all alot more to just buy up a bunch of different oils and test them (especially rotary specific oils vs. non-rotary specific).

 

I'm thinking the word "universal" is for all cars, not the RX8. Not sure though. If it does, then the column average that is definately for RX8's applies to a specific geographic location. Plus that right hand column doesn't indicate mileage. I think they owe you a bit more explanation on their report.

Nevertheless, I'll bet you are making the right decision. No changes really needed other than the 3k OCI.

 

I'm fairly sure that universal averages pertain to the specific engine model.

 

Interesting. This is pretty consistent with what I've been reading, though a lot of people are not as strict with their oil change intervals as I am.

On most cars, I would follow the manufacturer oil changed interval approximately.

But not the 8. I do change the oil every 3k miles. So with that, and the fact that Havoline does contain extra moly in the additive package, I will stick with Havoline.

 

The right most column is for my engine type specifically for sure. I know this because before they thought I had a different engine and had different numbers Their average numbers they claim is for 2700 miles.

I agree what I am doing is not as useful as it could be to others, but honestly just trying to keep an eye on my wear. If one oils seems to give me a drastic increase in wear then I would try another for sure. I agree just getting a test done on several oils would be ultra useful, but also ultra expensive

I just wanted to offer people what my results are and take any conclusions you can from them if any. At the very least I thought it my be interesting for others.

 

It's definately interesting to look at these reports. At 2700 miles on the "average" rotary, you appear to be doing pretty well...in fact PPM counts under some with 2/3 additional mileage on your oil fill.

Having said that, and as Jax indicated, they don't offer any information about what's happening with the apex seals. An example, and I think his screename was OMP Wankel, I'd seen some of his UOA's done at 45k and 47k miles. They looked fine.

He was meticulous in his care for the car using a cleaning premix and changing the oil every 2200 miles or so using what I recall was a MC synthetic blend (GRPII+?) At 49k, his engine died. No indication of catastrophic failure in his oil analysis. I don't know the failure mechanism, he never disclosed that information....but it wouldn't be a stretch to assume it was his apex seals or the springs that control their movement.

On the reports, yes, I looked at others and indeed the left hand column contain averages for a specific engine. The other averages column is for your engine (I suppose some customers have trouble adding and dividing so they do it for them). I'd prefer them to add additional information in that column....including "universal" averages for "all" engines. While looking at them in comparison to mine may not allow for any useful conclusions, the comparisons would be interesting.

 

very good thread and info on here rx8convert.

and what would results be for valvoline be if anyone knows... since it IS the choice of oils by top ASE technicians. is there a truth behind it, or just marketing gimmick... i wouldn't know. but it sure would be nice to find out.

i also use valvoline as my favorite brand.

also, nice to know that oil is not just oil. since the effort of you guys are pointing out that different brands are not created equal. i may just consider replacing quaker state with castrol as a better alternative...

good work guys. i now consider sticking with 3 brands of oil... castrol, valvoline, and havoline. man, this oil thread is making my head spin!
keep coming with the low-down on the oil secrets!

 

"Nine out of 10 dentists recommend Crest toothpaste". It's a marketing gimmick. Never, ever trust marketing. They might be telling the truth, but never on-purpose.

Truth is, it's been proven several times by independent, real-world studies that oil is just oil. Most famously Consumer Reports did a long-term study with NYC taxi cabs (I think), and found negligible differences in wear between off-brand grocery store oil and gold-plated Mobil 1. Oil companies hate that fact because it cuts their profits if you don't believe, so they spend $millions$ in marketing to convince you otherwise.

All that said, I've still bought into the hype and use Castrol GTX 10W30 in all of my vehicles. Mainly because the bottles are pretty, it's easy to remember, it goes on sale often, and "GTX" reminds me of the famous 323 GTX, which I want to own someday.

Here's the other report rx8convert22 promised you. I got the car at 15,000 miles, and have been driving it like a hooligan ever since. The previous owner is a hooligan too, but I don't think he drove it as hard. Oh, this oil has two track days on it, totalling almost three hours of full-throttle track time.

I can also post up a recent report from my Dodge truck for comparison. It has data for two reports, a year apart. I've done the transmission on the 8 too, and will post that report when I get it.

 

Oil isn't just oil, that's an incorrect statement and will end up confusing people. Provide some evidence of that before you make some blanket statement please.

 

Ah, we appear to have a Believer.

Oil is just oil.

Citations:
1. Reference to the 1996 Consumer Reports test. ("The surprising truth about motor oils" (July 1996). Consumer Reports: 10-13.)

2. And from the Blackstone Labs FAQ:

I'm not suggesting that people shouldn't use the right grade or brand names. I'm suggesting that people shouldn't overthink it too much or believe that because it costs more and the marketing says so, that it must be better.

Now, your turn. If you want to prove your blanket statement that "oil is not just oil", then please provide adequate citations that counter what professionals who test oil for a living say.

 

lol, that's all I can really say. Well go on preaching it

 

I agree Oil is Oil... just change it frequently and use at least a 5-30w in your 8