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Wondering if the stock BMW oil cooler run at the temp it runs by design given that we are using 10w-60? Not sure how much cooler other oil cooler get the oil? Ran across this article as I was looking for answers. Is there any verdict out there on this topic?

 

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Ah! didnt know that. I was under the impression guys were seeing lower oil temps reported by the gauge. don't know why I thought that.
 

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I'd say that link sucks... But you know how oil discussions go. Consider cold oil can be in the tens of thousands of cst. Let's pick a 0W20 oil with max 6200 cp cranking viscosity at -35C according to the SAE spec. At 100C minimum viscosity is 5.6 cst. So an engine specified for 0W-20 (a light oil by any standard) considers operation between 5.6 cst and 6200 cp right?

So what if we now use 60wt oil on the same engine. 60wt has a min hot viscosity of 21.9 cst. This number is perfectly within the range of 0W-20. And yes it's 400% thicker than 0W20. So what? That link makes a huge argument of 60wt being xxx% thicker.

Cold is the opposite obviously but I'm not talking cold. If cold was an issue then you'd see northern cars failing more often than FL and CA cars. And don't forget Australia. Guess what? Such data is not there because it doesn't exist.

People think thick evil hot 10w60 is the problem - yes it's thicker when hot and that's a feature! I'm sure some energy vampire will jump at me anyway for cold and for mixing cp and cst and whatnot - whatever.
 

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So what operating temps are you guys seeing with 10w60 oil? And by operating temps i mean daily driving wether hwy or city, not track. But if you have track temps then what are those too?

I am not following what you meant by this statement:

So what if we now use 60wt oil on the same engine. 60wt has a min hot viscosity of 21.9 cst. This number is perfectly within the range of 0W-20. And yes it's 400% thicker than 0W20. So what? That link makes a huge argument of 60wt being xxx% thicker.
I agree though that being thicker at higher temps is a feature or benefit of higher grade oil. But not having an e60 m5 i also wonder what temps do you guys see with this oil.
 

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On my e64 (which probably has the same oil cooling system as the e60), the usual oil temp on the odo gauge hovers just before 210° Fahrenheit. Sustained high revs/multiple red line pulls sees it climb to just over 210°. Highest I've seen it was about 2/3rds of the way to the next increment marker on the gauge after a hard pull on the highway followed immediately by a traffic jam on a 105° Fahrenheit day. Factory filled oil (Shell/Twinpower) topped up with Castrol Titanium 10w60.
 

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I am not following what you meant by this statement:
My point is 10w60 is often called too thick or heavy (as in the link you posted). But any lighter oil that's being warmed up will have the same viscosity as hot xxW60 (21.9 cst) at some point during the heating process. So if lighter oils are ok to use then hot xxW60 which has the same viscosity as the lighter oil just a few degrees colder also must be ok to use.

The few people that understand the above and still call 10w60 too thick is because of the 10w. Do they call 10w30 or 10w40 too thick as well? Yeah don't think so... 10w30/40 oils have been used for decades and nobody calls them too thick. Yes they're not rated for extreme cold temperatures and neither is 10w60. Truth is most people see 60 and instantly say its too thick - BS.

For the temp question, daily/hwy temps are right at the middle, few degrees above or below depending on season.
 

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I get it now, thanks. I did not post that link, someone else did.

In response to your post/point, while you are right in your claim, the issue is that w20 oil may be 22cst at 100F while w60 will be 22cst at operating temps, 210F. I dont push my car until its warmed up, thus my bearings will never see 22cst at ~max tq with w20 but w60 will be 22cst at operating temps when my rods will feel ~max tq. So in this sense it is too thick because we must compare apples-apples, or oil cst at operating temps. Does that make sense? (I didnt read that link btw, i done my oil research yrs ago.)

Now i am not saying that 22cst is too thick to protect bearings under max tq but it may be, and it certainly isnt 5cst, which could be opposite and too thin.

Just my 2c, as far as oil goes.

Now as far as operating temps, is there no way to log or readout actual temp rather than looking at the needle? The needle may not be most accurate or responsive.
 

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In response to your post/point, while you are right in your claim, the issue is that w20 oil may be 22cst at 100F while w60 will be 22cst at operating temps, 210F.
Sure, but the temp difference is not 110F. See the generic oil chart below. Viscosity really changes below 50 or 60C. Anything above 70C and we're talking very small changes. Hence my comment about the OP link that claims W60 is 400% thicker when hot than other oils - yes, so what?

Comparing W60 (not on the chart) to a W50 oil, the W50 will be at 22cst at 95C - just a 5C difference vs. the W60 hot temp. Nobody will claim an engine blew up or rod bearings failed because of running 5C hotter or colder right? In my made-up example of a W20 oil it will be at around 70C to be at 22cst. 70C oil is full temp on older engines. Newer cars run hotter for emissions/savings/longer oil intervals but I'd be perfectly fine pushing an engine with 70C oil. The S85 rev limiter goes to full range at 75C I believe.


 

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Yea i was making up numbers too. But looking at the chart we have @100c w40 at 16cst and w50 at 19cst. Thats 27% and 14% thinner respectively at operating temps. Not sure where 400% comes from or how relevant it is.

Again, i am not saying that it is too thick or not too thick. Just saying that we should compare them at same oil temp spec, ie 100c. The % diff may be even greater at lower temps, increasing as temps drop. But that isnt as relevant as comparing cst at temps of 80-100c say. Still, at 80c the % difference will be greater than 27 and 14.

So what? So perhaps thats why bearings need servicing? Perhaps not. I dont know enough to accept so what or argue other way, but if you had a pay increase or decrease of 27 or 16% i am sure you wouldn’t be saying so what. Its a big difference if you ask me. Would you accept some tolerance variation of 15-20% when building an engine?

Also, i dont feel safe pushing a performance car to the max with oil temps at 70c/160f. Again, perhaps thats why bearings get shot, perhaps not. But i wouldnt until needle gets to operating temp, that’s just me and what my common sense is telling me.

You guys are operating blind without being able to monitor pressure/temps though. This is just theory.
 

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For “comparison-wise” i use an oil which is [email protected] in a highly tuned 2.0L motor delivering at least 450hp/450tq. Thats a whole 45% thinner oil than w60 is.. are tolerances that much greater in a german than they are in a japanese?

Pressures of 90-65 cold-hot and temps of 215-225f depending on ambient and how hard you push it. Do you even know what your pressures are cold and hot? Because theoretical cst is not as important as real life pressures when cold and hot.
 

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I don't claim to have much knowledge in the field, but my takeaway from having looked at this issue briefly in the past (out of curiosity) is that viscosity is only one aspect of an oil's qualities, but it somehow dominates discussions. As I understand it, oil viscosity can be measured as a kinematic and as an absolute iscosity, which are two different measurements. Then you also have to take into account viscosity stability under changing temperature and load, as well as shear strength/film strength/ability to withstand load. On my understanding, yes a quality w60 oil will not have as high a flow rate as a w20 oil, but it more than compensates for this when the other factors are taken into account. Some oil manufacturers publish the performance of their oils in terms of these metrics (for example a comparison of the figures for the BMW Twinpower 10w60 with the Castrol Supercar/Edge/Titanium 10w60 on my understanding shows the Shell product to be a bit better performing in each test). One would assume that a quality performance engine has been engineered to negate any potential pitfalls of a very high viscosity oil, and that is why my beasty will only be drinking 10w60,especially since it sees 8000rpm regularly.
 

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My understanding is that there is theory and then there is practice. In practice all that matters is oil temp and oil pressure you see at 8000rpm really, and pressure will be inversely dependent on temp.

Also, i havent looked at shot e60 bearings but someone with experience can look at them and kind of tell if the damage is due to oil starvation or other issue like tolerances perhaps.

Id invest in an oil pressure and temp gauge, or some sort of obdii device giving me readouts. At least pressure if having to choose one of the two gauges.
 

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My understanding is that there is theory and then there is practice. In practice all that matters is oil temp and oil pressure you see at 8000rpm really, and pressure will be inversely dependent on temp.

Also, i havent looked at shot e60 bearings but someone with experience can look at them and kind of tell if the damage is due to oil starvation or other issue like tolerances perhaps.

Id invest in an oil pressure and temp gauge, or some sort of obdii device giving me readouts. At least pressure if having to choose one of the two gauges.
Yes you are right, ideally we should have an accurate real-time oil temp and pressure reading and this would be a good practice. At some point though i sort of implicitly trust the engineering and back off my own slightly ocd nature (one less thing to worry about). I would hate to start agonizing over perceived fluctuations in oil pressure if i had access to this additional metric.

Re rod bearings, really contentious issue it seems but personally I'm not too worried. My personal view is that the "wipe" wear pattern is normal settling in for this engine. The failed shells i have looked at here seem to be caused by other factors (debris/starvation/overheat). I suppose a realistic concern would be whether the po abused the vehicle, but really i just enjoy it nowadays without worry. Do what you think is the required maintenance and then in God we trust :)
 

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Here we go again, why not chime in. Comparing my E38 740 or 750 to my E60 M5. Cruising at 70mph the E38's are at 2000rpm the E60 is at 3000rpm, you can do the math rev/mile. We always look at mileage for a gauge of wear. So cruise at 2000rpm and never rev your engine over 6000rpm and it may last as long as a normal engine.

I for one will do a proper warm up, regular 3000k oil changes and enjoy may car the way it was meant to be driven and change my rod bearings. As for the oil temp it is regulated and the viscosity difference will have little effect when the oil is hot as Falco points out.
 

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Discussion Starter #17
not gonna pretend I know anything about oil, and probably because of that my take away from the article is 10W-60 has its place in certain cars ours was more or less mentioned. Did you guys see the other link from an older post in this board. some good info and racing oils, that need to be changed very frequently.

For those who asked or wanted a compare, I'm running just over the 210 mark here in Austin. Its been that way on 80 degree days and 110 degree days (even higher on 110 degree days if I bang shift). I'm not sure how accurate our dial gauges are tho...... Maybe I need to consider the RPI cooler?? Silver or Black?

Thanks for the discussion, always learning around here.
 
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Here we go again, why not chime in. Comparing my E38 740 or 750 to my E60 M5. Cruising at 70mph the E38's are at 2000rpm the E60 is at 3000rpm, you can do the math rev/mile. We always look at mileage for a gauge of wear. So cruise at 2000rpm and never rev your engine over 6000rpm and it may last as long as a normal engine.
ya, in the aviation world its engine hours. I always told the guys in my Firebird group, even tho it has 65K miles on it, its a low hour car because most of those miles were hwy miles.
 

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As for the oil temp it is regulated and the viscosity difference will have little effect when the oil is hot as Falco points out.
Not sure what you’re trying to say but there is a 45% difference between a 12cst and 22cst oil at 100c. If you had a pressure gauge you’d be able to visualize the “effect.” But you dont so you’re assuming and guessing, lets call it theorizing. And i am not suggesting you will see a 45% pressure delta, but i switched from w30 to w40 and pressure difference of 10psi @100C. 🤷🏻‍♂️

For those who asked or wanted a compare, I'm running just over the 210 mark here in Austin. Its been that way on 80 degree days and 110 degree days (even higher on 110 degree days if I bang shift). I'm not sure how accurate our dial gauges are tho......
Yes, i suspect it isnt accurate or better word would be very responsive to small changes. But i am only guessing based on not seeing mine move yet my temps fluctuate 10-15deg. (Another car)

Same goes for my water needle, temps can change 10-15deg but needle doesnt move.
 

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Not sure what you’re trying to say but there is a 45% difference between a 12cst and 22cst oil at 100c.
That's exactly my point. You're worried about a 10cst change. A 100x greater change occurs as oil goes from cold to hot. Yet no one would argue that's not ok. I bet that between seasons oil viscosity varies by that much. As oil shears same thing will happen. So yeah 10cst is nothing. Take this to the extreme and consider water at 1cst then you have a problem. But those discussions are for energy vampires.

There will be little to no effect on temp and pressure with a 10cst change unless at idle or on a worn engine with loose clearances. The BE guys showed that flow is greatly increased when hot with a thinner oil but temperature and pressure won't tell you that.
 
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