Thork'sGT3

I have recently done an analysis on the oil of my 997.1 GT3.
The procedure that I use, which is likely not the best, is to warm the engine up for approximately 5 to 10 minutes.
Crank case drained first then sump. Oil sample was taken from the crank case mid stream in the drain.
When I got the results back everything look good for metals etc.. The one concern in the report however, was the viscosity. It stated that there was a 3.6% dilution of fuel in the oil!
Oil was changed at 7500 km and I use 0-40 Millers.
Has anyone else out there have any experience with fuel dilution?
Where would this be coming from?
I realize that idling the car for 5-10 minutes and then draining is likely not correct due to cold start fuel mixture etc, but wanted to get other opinions.
Thanks RLs

Brent

NAM VET

While I do a Blackstone on all of our cars, on a periodic, occasional basis, just to see if anything may be showing up, I am no specialist on how to best use an oil analysis. Like you are wondering, perhaps idling for a period before draining may put at least a little fuel into the oil, soon to be evaporated with sustained high oil temps. Maybe next time, before you change your oil, add one of the fuel system cleaners, Techron is popular, then drain after a long, hot run and see what is there.

But then, what would I know. 3% of ten liters of oil sounds to me like a lot of gas.

all the best...

NV

Spyerx

short runs starts/stops not getting up to temp and not running hot can cause fuel and moisture in the oil. my fuel in oil depending on when i change it has been .8 - 1.5%.

FWIW, from my experience these engines aren't warm in 5-10 mins. Go drive the car and get the oil temp up to normal running then change it.

Macster

Only analyzed the oil once in my 2002 Boxster, shortly after I bought it, after I had put around 4K miles on the car. This was in the winter of 2002. I do not recall the fuel dilution number -- which means it was probably very low -- but the water content was quite high at 7%.

I attributed this to how cold blooded these engines are. I learned this after being prompted to monitor coolant temperature and observed how cold the engine ran even after having been run for some times. A 10 mile drive to work didn't get the engine very warm at all. Even blasting down the freeway at 75mph+ the engine ran surprisingly cool. Thus water a combustion byproduct was getting into the oil which is "normal" but not being boiled out.

This caused me to adapt a 5K mile oil/filter service interval and abandon the factory 15K mile oil/30K mile filter service schedule. 296K miles later the engine is just fine.

This leads me to this: In your case I think the fuel is mostly due to the extreme cold where you are and how rich the engine must be fueled to run in this extreme cold. Also, you probably don't drive the car very much and as a result the oil doesn't get hot enough to boil the fuel out of the oil. Even if you drive the car a lot as I had observed the engine doesn't get that hot so the oil doesn't get hot enough.

Absent any CEL or pending error codes pointing to a fueling problem -- due to say possibly a leaking injector -- I do not think what you have found regarding fuel dilution is a sign of anything more than you need to consider a shorter oil drain interval. At least in the cold weather. And be sure to start out the winter season with fresh oil in the engine. You do not want to enter the winter season with the dregs of summer oil in the engine.

RobT 394

I have performed oil analysis on a GT3 dedicated track car for 5 years now. The metals have mostly been ok. Occasionally you see something higher than normal that often goes away in a future report.

Fuel % is all over the map. The Blackstone guys thought this was a problem for a while however my local shop says it is normal with these engines. It goes from a TR to 2.8% with little difference in how I used the car or warmed up the engine. I am at the point of ignoring it since we cannot find a pattern or an issue to be concerned with.

Viscosity is the big issue on these engines. I am not an engine builder or engineer of engines but this is what we believe is going on. The viscosity breaks down and even after 1500 track miles the oil is essentially done. That is two weekends of hard use. This has been an issue with Mobil 1 and Motul fills. Have not tried Millers but plan to. The issue is that the oil is under such compression on the crank that it literally breaks down the oil to the point where the viscosity is no longer at spec. Blackstone originally thought this was from fuel. After numerous oil reports we are concluding that is not the case. Fuel % of TR and 2% have no impact on viscosity. Thus the conclusion is the mechanics of the engine break down viscosity.

Bottom line, change your oil frequently. It is breaking down sooner than you think.

NAM VET

I have wondered for awhile, if the Porsche factory engineers and test drivers who own Porsche's could confidentially tell the rest of us how often they change out the oil in their cars, what would they say? And what oil do they use? And would the rest of us feel perfectly secure in following the factory engineers change schedule? In years past, owner's manuals had specific viscosity suggestions based on the anticipated ambient temps, with those little bar graphs.

Me, I use Redline in everything I have that has a piston.

all the best....

NV

Thork'sGT3

NAM VET, Spyerx and Macster
I agree with your statements on time running and in fact idling the engine in cold weather for 10 minutes really isn't "warming" the engine at all. Definitely gets the oil warm, but that's it.
When speaking with the Porsche tech, whom I trust, he stated that he has seen this before. He really doesn't trust the fuel % part of the analysis as with the configuration of the flat six when you shut off the non- hot motor, the injectors may pulse a couple times letting the fuel to sit in the cylinders and seep under the rings.
Rob T 394
I think you correct in the interval changes. Though most of the miles on the motor (87,000 km) are highway as we live in the country, I still do about 6 track days a year including the Knox Mountain Hill Climb for Hands Together for a Cure hill climb in Kelowna. I usually change the oil in the fall before the car gets put "to bed" for the winter. In spring I run the car on the "new oil" for spring, summer, then change in fall again for storage. May need to do a mid summer change.

Thanks for the feedback

LexVan

Do you start and go, as you should? Or do you idle a lot to warm the car before you drive?

Do you idle a lot at track events? On the grid? In the paddock?

It's very easy for Blackstone to accurately measure the fuel dilution. It's a function of the flashpoint. I assume yours was pretty low. Well below 400.

Once there is fuel dilution, and viscosity breakdown/reduction, it does not reverse and self heal itself once the engine gets up to temp and burns the excess fuel off.

Thork'sGT3

LexVan - Yep, that's exactly what I do. We are on a country road for 4.5 km before the highway so literally I start and drive to the highway in second gear. Once at the highway it 100 - 130km/hr all the way in to work.
Never let the car idle, but always allow it time to warm up while driving before letting lose a bit.
You make mention that if there is fuel dilution that once you go for a good "blat" that the fuel will dissipate out of the oil. This was one of my questions in the OP. If this is what you meant, then thanks for clarifying.

Macster

Based on my observation of my Boxster's coolant temperature using an OBD2 code reader/data viewer, the type of driving you engage in does not get the engine the hottest. In cold weather it is hard to get the engine real hot and by this I mean hot enough to trigger the radiator fans to come on. The best way though how successful you will be using it depends upon ambient temperature is to drive around town at moderate speeds and with the usual stop/go driving.

The other way is to take the car out somewhere on a twisty road and engage in very spirited driving.

Thanks to my local dealer's SA I have a Cayenne diesel to drive as a loaner while one of my cars is in for some work. This Cayenne has a digital (and analog) display of the coolant temperature and oil temperature (and oil pressure). While from a dead cold start -- "dead cold" being around 30F -- the coolant temp will be 200F in just a couple of miles or less of easy driving. However, I can be 10+ miles down the road and the oil temperature will still be under the coolant temperature.

This is my 30 mile commute to work which involves a mile or less of surface street driving and the rest freeway driving. During the holidays traffic has been light to the point I can maintain a nearly 65mph average speed during the morning commute. The evening commute is sometimes affected by heavier traffic seeking to get out of the area for the holiday. I can be half way to work before the oll temperature reaches 200F and then it continues to climb sometimes reaching 231F (the highest) as I make way to the office.

Macster

Your post just underscores what I have said -- this was not my original thought but was passed on to me by my auto-tech buddies who also tracked their cars -- and that is to show up at the track with fresh oil. Every time.

It is false economy to try to stretch oil over several track events separated by time and probably with some street driving in between.

Ur20v

The crank doesn't stretch the oil at all - the bearing surface area is large. Its the cam lobes/bucket contact areas and gears and chains that produce the high loads on very small contact patchs that cause issue to the oil, combin this with fuel, combustion products and water that mean regular changes are best.

RobT 394

^^^ I will buy this. The high loads on small contact patches is the single biggest issue on these motors and what I see in oil analysis. The best oil is one that is fresh.

Thork'sGT3

Great thread and learning lots which is what's great about RL. More into this than which wax to use on the paint.
Macster - thanks for the info. My drive into work, when I take the GT3 is about an hour each way. All highway as well. Rarely start the car at less than +10 C (50 F), and never let idle. Reason for the idling before oil change is the snow on our steep driveway
RobT 394 - I do what would amount to 4-5 true track days a year. Time for each run would be 20 minutes, and 5-6 times per day so definitely not 1500 miles total for the year.
Ur20v - interesting point regarding oil breakdown due to small surface areas at pressure vs larger crank bearing surfaces. Makes good sense.
I will see if I can add the AGAT oil analysis to this thread.

I think the best plan moving forward is to do frequent tests on the oil and trend it throughout the summer with a full change at 3500km (2100 miles) if analysis indicates it is needed.
Has anyone placed a drain valve on the sump tank drain plug so that periodic analysis is possible without draining all the oil? This might be a handy thing to have.
I will keep everyone up to date on the results

Thork'sGT3

Here is the AGAT Oil Analysis for you to see. The first one is from my wife's JCW. Second is the GT3.
Let me know your thoughts.

Thanks again for all the input.

Brent