Oil Analysis: 15,000 mi, Rotella T6, '90 C4

[porterdog]

These are the results from the oil analysis I had done at 140k; 15k on the oil.

Last sample and thread can be seen here.

I'm pleased with the results and will continue to use this oil at 15k oil change intervals.

Note that 4qt is the total consumption over the interval (not 7qt).

[drtyler]

That is really good. I bet you are pleased!

How is your oil pressure when warm using 5w40?

DT

[porsche930dude]

how long time wise was the oil in the car?

[M.D. Holloway]

Interesting

[M.D. Holloway]

I'm not liking the 1% fuel dilution results. I really don't like any fuel showing up in engine oil analysis.
The cause of such could be:
- Ring, liner or valve train wear
- Extended idling
- Faulty injectors, pump
- Incomplete combustion
- Intermittent service
- Incorrect air to fuel ratio

But the effect could be:
- Loss of oil film strength on the compression ring
- Increased wear (due to comprimised film strength
- Decreased oil pressure
- Rapid failure due to increased wear particles as well as a rapid increase in oil oxidation. Oil cooled engines run hotter leading to accelerated oxidation.

I would be careful. I don't like it, nope, I just don't like it...

[Trackrash]

Wow 15K miles, impressive. How do the viscosity numbers compare with the oil when new?

[mikesride]

Doesn't it say "less than 1%" under fuel dilution MD? Is that the lowest measurement this particular test picks up perhaps?

[M.D. Holloway]

The previous test was above 1%, but if it was less than 0.5% I think Blackstone would report a 0. Having a <1% could mean up to 1% but not equal. Strange to report it that way. The test now uses a GC but some labs still use an FTIR which isn't as accurate. I will do some checking to see what Blackstone uses - still don't like anything but a 0 for fuel. Not such things as acceptable limits in a gasoline engine IMO when it comes to fuel dilution. Diesel is one thing, this is different...

[porterdog]

Originally Posted by porsche930dude

how long time wise was the oil in the car?

Installed April 2012

[RWebb]

so, 1 year and 5 months

my guess is that fuel would be lower if the car were driven more on longer trips - is it a little driven, or short trip car?

Mike - define your acronyms for folks...

[M.D. Holloway]

Originally Posted by RWebb

so, 1 year and 5 months

my guess is that fuel would be lower if the car were driven more on longer trips - is it a little driven, or short trip car?

Mike - define your acronyms for folks...

Fourier-Transform Infrared Spectrometer - FTIR. Identifies organic functional groups by measuring infrared absorption at various wavelengths. Expressed as absorbance/centimeter or percent. Tests used toqualify

• Water
• Oxidation
• Nitration
• Thermal Degradation
• Glycol
• Phenol Additives
• Sulfur Compounds
• Fuel (no longer
• Soot

Gas Chromatography - GC. Technique used to separate volatile organic compounds, such as fuel, from the oil by injecting a small amount of sample into the GC, it is forced into a heated column.

The organic compounds are separated by their boiling point behavior as they are forced along the column from lower temperatures to higher ones.

A detector transmits the concentrations of the specific compounds to a recorder which converts the column peaks into percent. Preferred method - more accurate, less variation due to the ability to discern data without overlapping of peaks that the FTIR would experience.

[M.D. Holloway]

not a fan of Polaris Labs

[porterdog]

Originally Posted by RWebb

is it a little driven, or short trip car?

Averaged almost 900 miles a month over this change.

"But the effect could be:
- Loss of oil film strength on the compression ring
- Increased wear (due to comprimised film strength
- Decreased oil pressure
- Rapid failure due to increased wear particles as well as a rapid increase in oil oxidation. Oil cooled engines run hotter leading to accelerated oxidation."

Except that the rest of the analysis shows that none of this is going on (probably because there is no fuel in the oil; results this time as well as last were "<1%, estimate.")

[Hydrocket]

Originally Posted by M.D. Holloway

not a fan of Polaris Labs

Well when can we start using your oil analysis service??

[Ronnie's.930]

I've got to call B.S.() on some of M.D. Holloway's comments - one percent fuel dilution, in a gasoline engine, is normal and not a cause for concern in any way, shape or form, and in fact, you've got to see numbers above 2.5% to even give it a second thought (and even then, not a big deal at all).

[M.D. Holloway]

Got to disagree Ronnie...but I will say that D. Ljubas, H. Krpan, I. Matanović did prove that 3-5% fuel dilution will not have a drastic effect on viscosity or flash point, Jim Fitch of Noria has writen that 2% will lead to issues from defective injectors commonly causes wash-down of oil on cylinder liners which accelerates ring, piston and cylinder wear. It also causes high blow-by conditions and increased oil consumption (reverse blow-by). He goes on to say severe fuel dilution dilutes the concentration of oil additives and hence, diluting their effectiveness. Severe is above 2% according to his defntion.

Now much of the critical call points that Polaris and Blackstones uses is based on fuel having a damning effect on viscosity - that being siad yes you can have up to 5% fuel dilution and be in the safe zone...for viscosity. But not for oil oxidation.

The compelling arguement comes from a few different oil makers - as little as 1% fuel dilution in gasloine engines increases the oxidation rate of the oil. These are presentations done at a few differnt conference I attended - I shall look to dig up the findings. It was interesting because it comes on the heals of the ethanol debate. Now, thats now to say pure gasoline will lead be different. Oxidation will still increase. The other fact remains is that E15 will increase the oxidation rate of the oil at low concentrations.

I'm gonna look for the presnetation on the kinetics of it. I also have personally seen large pools of data of oil analysis for two different oil companies working on extended drain intervals and the case where there was an increase (any %) would increase the oxidation rate of oil.

[porterdog]

Originally Posted by M.D. Holloway

...2% will lead to issues from defective injectors commonly causes wash-down of oil on cylinder liners which accelerates ring, piston and cylinder wear. It also causes high blow-by conditions and increased oil consumption (reverse blow-by). He goes on to say severe fuel dilution dilutes the concentration of oil additives and hence, diluting their effectiveness.

Yeah, I don't think gas would be a very good lubricant for spendy German whirly bits, BUT...

1. If I were looking at accelerated ring/piston/cylinder wear that would show up in the analysis. Iron and Alu numbers look great and on-trend.

2. My oil consumption is so low it's ridiculous; the car has 140,000 miles on it and uses one quart every 3750 miles, and I park on cardboard because it drips.

For the sake of clarity, I did send Polaris an email asking what exactly is meant by "<1-Estimate" and also which measurement technique they use. I'll post up their reply.

Also for clarity I'll explain that the main reason I ran these analyses is that I do not like changing the oil in this car and wanted to be sure that I could get away with 15k mile change intervals (Answer: Yes!). I also wanted to know if I was hurting it by using cheap Walmart oil (Answer: No!).

If people start to realize that swapping out their boutique oil every 3k may be overkill, so much the better.

[unclebilly]

Rotella T6 is hardly cheap walmart oil, even though you can buy it there relatively in expensively. It is NOT the Walmart bra d stuff.

[porterdog]

Compare the price of Rotella T6 to Motul, Brad Penn, or Joe Gibbs and you'll see what I mean about cheap walmart oil, Uncle B.

Here's Polaris' response to my inquiry about the fuel dilution. At least the response was fast

"The fuel dilution was not physically measured on your sample. We test fuel dilution by GC if the viscosity is 1 cSt lower than the expected result for the lubricant. If the viscosity is strong, then we estimate that fuel is less that 1% because fuel at levels below 1% typically do not affect viscosity. We use the estimate to help keep overall costs down for the customer."

[unclebilly]

Originally Posted by porterdog

Compare the price of Rotella T6 to Motul, Brad Penn, or Joe Gibbs and you'll see what I mean about cheap walmart oil, Uncle B.

Here's Polaris' response to my inquiry about the fuel dilution. At least the response was fast

"The fuel dilution was not physically measured on your sample. We test fuel dilution by GC if the viscosity is 1 cSt lower than the expected result for the lubricant. If the viscosity is strong, then we estimate that fuel is less that 1% because fuel at levels below 1% typically do not affect viscosity. We use the estimate to help keep overall costs down for the customer."

Yup, I am very aware of the costs... I run Rotella in my daily drivers, my 4WD Case Tractor, my Mack dump truck and the chump car and change it every race but my other Porsches all get Brad Penn.

It is a good quality synthetic diesel motor oil used intended for extended oil change intervals in long haul trucks. It there any surprise it should last 15k in a light duty air cooled engine such as a 3.6L 964 engine?