M1 0w-40 going out of grade in 2500 miles;

[MikenOH]

I hear what you're saying, Doug--Raby went out of his way to broach this topic so I'm guessing his got something back that up other than a notion on this. We'll see, since he's got more info on what he's doing on the 9A1 engine coming out soon.

BTW, I looked up a few of my old oil samples--if I can figure out a way of posting them I will.
On an 06 987, I had 5500 miles on M1 15W-50--and 4 track days--with a 100 deg.C viscosity number of 13.8. I also had a lubromoly 5W-40 with 2800 miles and 4 track days with the same rating of 12.5. The LM seemed to provide a pretty significant difference relative to my friends experience with the M1 0w-40.

 

[CATERHAM]

Originally Posted By: MikenOH

BTW, I looked up a few of my old oil samples--if I can figure out a way of posting them I will.
On an 06 987, I had 5500 miles on M1 15W-50--and 4 track days--with a 100 deg.C viscosity number of 13.8. I also had a lubromoly 5W-40 with 2800 miles and 4 track days with the same rating of 12.5. The LM seemed to provide a pretty significant difference relative to my friends experience with the M1 0w-40.

Once again those KV100 values have no relevance without also referencing the actual maximum oil temp's and minimum OP.

 

[MikenOH]

Caterham--thanks for the reply.

I just recently picked a data logging program that will give me coolant and oil temps via a OBD II reader; with a little luck next year they may expand this to oil pressure also. It is currently displayed on the car's gauges--oil pressure and temps--but until I can pull the pressure reading via a connection thru an OBD reader there isn't much I can record.

Assuming I can pull oil temps/pressure reading via the OBD connection next year, what should I be looking for to gain a better idea if the oil is doing it's job--other than seeing lot of high wear numbers of certain metals?
-Specific oil/pressure numbers over time or at a specific engine speed?
-Reaching a specific temperature or oil pressure reading?

As an unscientific example, oil temps on the gauge at a recent 3 day trip to VIR usually read about 230deg F. during a session(ambient temps were in the 60-70 range)--a bit more or less depending on how far into the session I was. Oil pressure doesn't seem to vary much except on revs--30-40psi.
BTW--the 981/991 Porsche--when in sport mode, has a different oil cooling scheme at work vs. normal mode; I don't have the details in front of me but when the sport mode is engaged, the engine is programed to provide better cooling to the oil. I've run the car with sport mode on and off in successive laps --same speeds/ambient temps-- and the with sport on, the oil runs at least 20deg. F cooler.

Also,I suspect this that is viscosity test # is included in the analysis for a reason,otherwise I can't think why Blackstone include it in the test. Lacking the specifics on oil temps/pressures during the sample time frame of usage, can we learn anything from this number that is useful?

Again, thanks for your response.

 

[CATERHAM]

Firstly oil pressure correlates to HTHSV not KV100.
Secondly, the reading on an OP gauge is a proxy for operational viscosity. At the same given engine rpm, the higher the OP the higher the actual operational viscosity of the oil.
Consequently in comparing the operational viscosity of different oils you must do it at the same exact engine rpm and oil temperature. Under those same conditions, the oil with the higher OP reading will be the heavier oil.

All engines have a minimum recommended test OP spec'.
For my 928 it's 5 bar (72.5psi) at 5,000 rpm at 80C oil temp's.
For an engine in good nick your're actually OP will be well above that. Running the spec' M1 0W-40 even at normal oil temp's of 93-95C the OP will be above 5 bar.

For the 981/991 engine series, if you do some research you should be able to fine out what the safe minimum recommended oil is at elevated rev's. If you maintain that level of operational viscosity on track then you've eliminated viscosity as a factor in engine wear.

As Doug pointed out, with an actual OP gauge you'll also know if you're ever experiencing oil starvation during some high G corning. Avoiding that is far more critical to engine survival than a few ppm on a UOA.

 

[CATERHAM]

I should add that 110C (230F) oil temp's should be no problem at maintaining more than adequate OP with M1 0W-40 unless you've got some serious fuel dilution. BTW that's another reason to install an OP gauge to monitor the net effect on operational viscosity of oil shear/fuel dilution.