here is mine
997.2 0W40 ( Canadian Tire brand)
Winter driven - 5k kms, short trips and cold

 

Maybe it's more the test used to determine the fuel dilution (e.g. approximation based on flashpoint rather than FTIR) but I am surprised that, even on a DFI engine doing short trips with winter blend fuel, the oil has that much dilution after only 5K kms. 2.9% is a lot...... results/wear looks good though.

 

2,5% fuel, your profile would explain that. I bet you took the sample when draining the oil cold?

 

That's correct! Blackstone measurement is based on a flashpoint, whereas Wearcheck uses ASTM (GC) measure....

There is a great thread that discusses this by a fellow Canuck ! @Eric Buckley
He has swapped the injectors to find the same issue occurring..

Thread
https://rennlist.com/forums/997-foru...e-cause-2.html




Correct, the car was not driven for a while and the oil was rather cold.... never again - takes forever to drain.

 

Thanks for the link. Wow, 3.1% fuel dilution on Eric's 5/1/2020 analysis -- that is shocking. I couldn't tell but hopefully Eric swapped the injectors with new OE (not rebuilt/cleaned). There is no question that short trips and idling the engine will cause more fuel dilution since the ring seal isn't as good...and winter blend is worse. But 3% is really high and makes me think something else could be in play.

In that link it seems folks were confused about crankcase vacuum between 997.1 and 997.2. The direct injected 997.2 crankcase vacuum is almost 3 times what it is on the port injected 997.1. Several brands bumped the vacuum after the fact to help ring seal, etc (need a new AOS/PCV).

Also for Eric's question: What I would like to find is an oil that loses less viscosity with the amount of fuel dilution that I have. Some oils like Driven DI40 will inherently hold less fuel in suspension.

 

I don't have that car anymore, but it continued to show around 3% Fuel Dilution with 5000km/3000mi between oil changes. It always ran very well, and I put almost 100,000km on that car. The number had jumped up by about 0.5% when I changed labs from Polaris to WearCheck; I think due to some difference in the way they measure. Even when the Fuel Dilution was over 3% WearCheck still characterized it as "Light fuel dilution occurring". I think most of the cars do this, and it's not a big deal. The car was driven 160km/100mi per day, highway, year round. Essentially no short trips. The replacement injectors were Porsche supplied rebuilt. I don't think that's why the Fuel Dilution continued; I think the original injectors were never the reason and the "problem" may just be inherent and widespread. If you are only using Blackstone you just don't know. Even using WearCheck I still have to specifically ask them to do the Gasoline Fuel Dilution test each time on my sample, or they won't do it and will report it as 0% (and not as "not tested"). I have had to ask them to retest when I forgot to specifically request the Fuel Dilution test and my dilution magically went to zero. When I asked them about this they said that they only do the Gasoline Fuel Dilution test if the sample shows signs (to them, in some unclear way) of having fuel dilution, in which case they will run the test to quantify the amount. So, when they look at my samples they think they look undiluted, but when I ask them to go ahead and measure anyway they come up with numbers like 3%. When I was using Polaris I didn't have to ask to have them do the test and they would report about 2.5%. I think many cars would show numbers above 2% if they sent their sample to WearCheck and specifically requested that the Gasoline Fuel Dilution test be run on their sample. I now have a 2011 Carrera and it's been running DI40 since before I got it and I've changed the oil once so far, with DI40, and it came back with 2.4% Fuel Dilution. Viscosity is 12.2, which is better than the Liqui Moly was doing. This car seems to use very little oil, the previous one used 500ml or a bit more per 5000km. Both exhibit Fuel Dilution. Both run well.

 

I agree that Blackstone's fuel dilution measure is not accurate and not worth paying any attention to. But I would be curious to see the WearCheck measurement vis-a-vis a FTIR test. In post #97 I see a previous WearCheck test with a 3.7% fuel dilution -- that is very high and I would be curious if it is independently verified. It is also strange that the company considers 3%+ to be only "light fuel dilution" and, similarly, that they think the samples are undiluted but when you ask them to test it comes back with such high measurements. I mean what do they consider "high" fuel dilution? Good lord.

No surprise that the dilution came back lower with DI40. Since you just switched, you will likely see the fuel dilution further decrease (and viscosity increase) in subsequent oil changes as additive clash is completely eliminated. I am utilizing 5K mile OCIs and my fuel dilution dropped by 1/3 between my first analysis after switching and the long term trend......but it took 2-3 OCIs.

 

I did not "just switch" to DI40. It is a different car, and I'm told that this car has had DI40 in it for 10's of thousands of miles. There is no reason to think the Fuel Dilution will "further decrease", since nothing is new/different except possibly driving patterns. WearCheck claims to do their Fuel Dilution test using the ASTM Gas Chromatography (GC) method. As I understand it the ASTM method divides the sample into components in the same way as a FTIR test, but the way the separated components are measured is different. Both WearCheck and Polaris have found Fuel Dilution in every sample I have sent, from 2 cars, but the numbers are about 0.5% lower as reported by Polaris. In the case of WearCheck I have had to ask them to do the test, otherwise they report 0%. From what I can read in some cases the ASTM test can be fooled by certain oil formulations that contain components with similar boiling points as compared to gasoline. Maybe both the Lubri Moly (old car) and DI40 (current car) oils fool the test to some degree, both at WearCheck and at Polaris? Is anyone aware of a lab that is known to use a FTIR method to measure Fuel Dilution?

 

I misunderstood, I apologize -- the previous owner had already been running DI40 and you just continued doing so in your first oil change. Sounds like you bought from a knowledgeable owner.

Speediagnostix uses FTIR.

 

Thanks silver_tt for the pointer on Speediagnostix. I have tried 4 different labs, but not them. I once sent 4 samples from a single oil change to the 4 different labs. On my next oil change I'll take 2 samples and send one to WearCheck and the other to Speediagnostix. We'll see how they compare. It seems that I bought the latest car from a series of knowledgeable owners, as I'm told the owner before the one I bought from was also using DI40.

 

I've used Speediagnostix on my last three oil changes. It's pretty pricy but I do appreciate that all my questions were answered by Lake Speed in a fairly quick manner. That adds to the value for me. That said, I'm going to give https://oilvue.com/ a try for my next analysis. It's been recommended to me as they do a good job with capturing particles that are larger and are missed by other UOA companies. It could be quite useful where you think you're seeing a drop in wear metals but in reality they are not being captured due to size. Curious if anyone has used Oil Vue before. It's half the price of Speediagnostix.

 

Hi all, submitting this for review. Mine is a low mileage 6-speed GTS, and I bought the car with 1800 miles two years ago.
These are the two oil changes since purchase.
Filter inspection (first time) yielded about 4 tiny (< 0.5mm) flecks of alloy (non-magnetic), second time had only two flecks.
Mobil 1 0W-40 (1) Mobil 1 5W-40 (2). Euro blends.
Car has had zero issues. I do exercise the engine each weekend I drive it.
Appreciate any feedback, not sure on the Molybdenum reading, which way is better?
EDIT - the oil was changed right at 1800 miles when purchased, so both samples are roughly equal at 1500 miles.

 

I'd recommend a better oil. 9ppm of iron in only 1,500 miles is kind of high. I see less than that on 5,000 mile change intervals on mine.

Switch to Driven DI40 or Liqui-Moly or Motul.

 

Its very interesting to see the old differences on the US market against the European market.

 

Thanks for the review and response.
I just did that - Liqui-Moly 5W40 Leichtlauf high tech 5w-40. Could the high iron number be possibly from the low miles on the engine (some break-in still)?