oil pressure 5w50 VS 10W60

[maicol76]

I'm always using logger in every track driving.

red line : Red line 5W50
blue line : Liqui Moly 10w60

outside temp : blue(3C higher) > red

Channel 4 in photo is oil pressure data.

blue's oil temp is lower than red's , but red's oil pressure is higher than blue's.

the reason why?

Which is better for our S65 engine?

[8600RPM]

Less viscosity , faster flow which means variable oil pump is pumping harder which means higher pressure

[Hujan]

Not sure how to interpret the pressure numbers, but I'll be curious to see what others say.

I do like the look of those viscosity numbers of the Redline 5w50 compared to Castrol 10w60, though. Less viscous at cold temps, but comparable viscosity at high temps.

[Leonardo629]

BMW tis states operating oil pressure should be between 4-6bars, so it looks like you are fine with either oil in that department.

It all boils down to protection, if you can subject both oil to the same track routine before performing oil analysis. I wouldn't overlook cold start protection either.

[Sneaky Pete]

Originally Posted by 8600RPM

Less viscosity , faster flow which means variable oil pump is pumping harder which means higher pressure

Sort of...The oil pump has an internal oil pressure spring which adjusts the rate at which the oil is pumped to maintain the pre-set oil pressure - a less viscous oil should lead to greater flow all else being equal....not at a higher pressure though but at the pressure pre-set by the spring.
IIUC The oil pressure should be the same for both oils in principle.

[dparm]

Originally Posted by Hujan

Not sure how to interpret the pressure numbers, but I'll be curious to see what others say.

I do like the look of those viscosity numbers of the Redline 5w50 compared to Castrol 10w60, though. Less viscous at cold temps, but comparable viscosity at high temps.

The problem is that we can't directly compare cold flow (and the more important pumpability) properties of a 5w50 and 10w60 because the MRV & CCS measurements are performed at different temperatures for those viscosities.

[dparm]

Originally Posted by Sneaky Pete

Sort of...The oil pump has an internal oil pressure spring which adjusts the rate at which the oil is pumped to maintain the pre-set oil pressure - a less viscous oil should lead to greater flow all else being equal....not at a higher pressure though but at the pressure pre-set by the spring.
IIUC The oil pressure should be the same for both oils in principle.

If we look at the chart, they're within 5% of each other, ignoring extreme values. I don't know what the sensor's margin of error is, but clearly they're maintaining very similar pressure. If I had to nitpick, I would say that the LM is a bit closer to that 4.0 lower bound on a few instances. Without knowing the age of the oils, it's hard to immediately say that's a problem. (e.g. if the Red Line was fresh out of the bottle, it's likely going to be thicker than the same oil with 5,000 miles on it)

[dparm]

Good post, OP. I don't know if we can conclusively say one is better or worse. That's making it too black-and-white, when many things are really just shades of gray.

A few of my thoughts:

1. Slightly lower oil temps are a good thing, but it's very slight -- dare I say within the margin of error for the sensors. Both are very stout oils and should be able to handle the high temps.

2. Per Leonardo's post, you're still within spec for oil pressure, so you *probably* could use the 5w50 without any ill-effects. The argument still exists for API-certified oils and manufacturer-certs, of course, something that Red Line does not pursue.

3. I would also be interested in seeing how these oils withstand repeated abuse via a UOA. Perhaps one is a bit more stout and can handle fuel dilution better, or will stay more in-grade, for example.

4. How fresh was the oil in both cases? Not a fair comparison if one had just been poured in a few hundred miles ago but the other had 5,000 miles on it.

[Hujan]

Originally Posted by dparm

The problem is that we can't directly compare cold flow (and the more important pumpability) properties of a 5w50 and 10w60 because the MRV & CCS measurements are performed at different temperatures for those viscosities.

Really? So there's no way to compare the cold flow of different weight oils? I find that hard to believe. There has to be some absolute, empirical value for viscosity that can be compared.

[Leonardo629]

Are CCS and MRV values relevant when you never start your car at those gruesome temperatures?

[dparm]

Originally Posted by Hujan

Really? So there's no way to compare the cold flow of different weight oils? I find that hard to believe. There has to be some absolute, empirical value for viscosity that can be compared.

Exactly, it is idiotic. And many blenders don't even bother listing MRV or CCS values at all...and calling or emailing will get you nothing either.

Pumpability testing is performed 5 degrees colder than the cold cranking test. Why? You don't want the engine to start if the pump can't supply oil, of course.

Here's how it works, roughly:
https://en.wikipedia.org/wiki/Cold-cranking_simulator

[Sneaky Pete]

Originally Posted by dparm

If we look at the chart, they're within 5% of each other, ignoring extreme values. I don't know what the sensor's margin of error is, but clearly they're maintaining very similar pressure.

I believe this is the S65s oil pump...the slide valve is spring loaded so its not high tech. But it should be able to keep to somewhere around its target of 5 bar (IIRC) inside the oil pump itself.

[maicol76]

I've changed 10w60 oil every 3~5 track driving.
Usually changing oil is done under 3000miles.
Every UOA, especially viscosity and TBN are perfect and almost same as VOA for short mileage.

10w60 in photo was drained after using only 1~2000miles, because I decided to use lower viscosity 5w50 for winter season track driving.

And data is from same tack, driver(me) and lap time, difference of outside temp is only 3C.
10w60 data from 2016-01-10
5w50 data from 2016-01-22

[Sneaky Pete]

I guess it could be that the 10W60 sheared down to a lower viscosity after it 1-2000 miles of use than the new 5W50.
If the oil pump worked at 100% efficiency the oil pressure graph line would be flat at 5 bar for any oil (within reason). In reality the pump is constantly chasing the oil flow demands of the engine and the pressure varies.
It certainly would be interestingly to know why oil is theoretically leaving the oil pump at 5 bar and arriving at the pressure sensor at a different pressure for different viscosity oils.

[Hujan]

OP, it would be great to see a UOA of the 5w-50 if you can grab and post one.

[8600RPM]

Where is bmlvr when you need him

[jcolley]

Originally Posted by Sneaky Pete

...It certainly would be interestingly to know why oil is theoretically leaving the oil pump at 5 bar and arriving at the pressure sensor at a different pressure for different viscosity oils.

For more depth:

https://en.wikipedia.org/wiki/Darcy%...sbach_equation

[Sneaky Pete]

Given the very short distances involved is the Darcy–Weisbach effect going to make much difference?

[jcolley]

Yes. Especially given the small diameter passageways for the fluid. I would have to look at the location of the sensor in relation to the filter, but if it's downstream then the pressure drop across the filter would also factor in (also directly proportional to fluid viscosity). If there were no difference in pressure from the pump discharge to the oil pressure sensor, there would be now fluid flow between the two. Pressure is the motive force.

Edit: from a systems design perspective, it makes more sense to locate the fluid pressure sensorn downstream of the filter as it provides a warning of a leak in the filter assembly.

[Sneaky Pete]

The pressure switch is indeed next in line after the filter.
However after the sensor there is the loop back feed #24 to the pump which ought to regulate any drop in pressure relative to the pump outlet pressure...or not?

[Green-Eggs]

Originally Posted by dparm

The problem is that we can't directly compare cold flow (and the more important pumpability) properties of a 5w50 and 10w60 because the MRV & CCS measurements are performed at different temperatures for those viscosities.

Originally Posted by Hujan

Really? So there's no way to compare the cold flow of different weight oils? I find that hard to believe. There has to be some absolute, empirical value for viscosity that can be compared.

Originally Posted by dparm

Exactly, it is idiotic. And many blenders don't even bother listing MRV or CCS values at all...and calling or emailing will get you nothing either.

Pumpability testing is performed 5 degrees colder than the cold cranking test. Why? You don't want the engine to start if the pump can't supply oil, of course.

Here's how it works, roughly:
https://en.wikipedia.org/wiki/Cold-cranking_simulator

Flow Technologies turbine flow meter is viscosity and temperature correcting. You tell them what oil you are using, and they develop the calibration curves for temperature and viscosity correction. You upload the calibration curve to the meter. The result is your flow is accurate for the type of oil you are using.

This is the meter we are using on the BE Bearings test car. We have purchased calibrations for four different oils, but I don't remember which ones at the moment. Right now, we have the meter calibrated for TWS 10W60 and that's what we're running in the car.

http://www.ftimeters.com/products/tu.../ft_series.htm
http://www.ftimeters.com/tech_librar..._viscosity.htm

[Hujan]

Originally Posted by Green-Eggs

Flow Technologies turbine flow meter is viscosity and temperature correcting. You tell them what oil you are using, and they develop the calibration curves for temperature and viscosity correction. You upload the calibration curve to the meter. The result is your flow is accurate for the type of oil you are using.

This is the meter we are using on the BE Bearings test car. We have purchased calibrations for four different oils, but I don't remember which ones at the moment. Right now, we have the meter calibrated for TWS 10W60 and that's what we're running in the car.

http://www.ftimeters.com/products/tu.../ft_series.htm
http://www.ftimeters.com/tech_librar..._viscosity.htm

Interesting. What is the goal of your testing? Are you trying to identify the ideal viscosity for the S65 given it's clearances? Please say yes.