[bmw201113]

Hey all I have a e92 lci and my oil temperature just hit 260 it didn't go over or anything but I was wondering if that's a sign or a symptom of a issue occurring? I've heard from a couple people that bmw tend to run hot but I guess that seems to hot for mental comfort to me. I did search the forum but couldn't reach any definitive answer

[N54Angel]

Same, mine hits 260 on average days and depending on how I drive it. Only way to control that is with an oil cooler. For now I don't have one as its getting colder in my state. But my car hits 260 on normal days.

[Soul_Glo]

With flashpoint of oil being 424F (around 260 C), I wouldn't worry about it as you are nowhere near that.

[Terraphantm]

Originally Posted by Broken_Gearbox

With flashpoint of oil being 424F (around 260 C), I wouldn't worry about it as you are nowhere near that.

Meh just because you don't hit flashpoint until 260ºC doesn't mean you want the oil to run super hot. It does get quite thin at higher temperatures, and it's also more likely to oxidize the longer you spend at higher temperatures.

260ºF is probably okay for an N52 on a hot day though. But that's about the upper limit of my comfort zone.

[bmw201113]

Thanks for all the responses you guys ease my mind lol

[Taskmaster]

Mine never goes above 240-250. Good to know.

[E91 M Sport]

Originally Posted by Terraphantm

It does get quite thin at higher temperatures...

That's a common misconception. In normal use the oil's viscosity improvers actually thicken the oil as its temperature increased in order to maintain proper protection.

http://www.belray.com/what-exactly-d...ignations-mean

[tdavis42]

Originally Posted by bmw201113

Hey all I have a e92 lci and my oil temperature just hit 260 it didn't go over or anything but I was wondering if that's a sign or a symptom of a issue occurring? I've heard from a couple people that bmw tend to run hot but I guess that seems to hot for mental comfort to me. I did search the forum but couldn't reach any definitive answer

What part of AZ do you live in? Mines been running fine in Phx for a while although I do notice it gets sluggish when its 110+ out.

[bmw201113]

I'm in Tucson

[Tom Droze]

Originally Posted by bmw201113

I'm in Tucson

My condolences.

[bmw201113]

Originally Posted by Tom Droze

My condolences.

Lmfao hahaha I know right

[Soul_Glo]

I was in Glendale and moved to the UK last year.

[tdavis42]

Originally Posted by Tom Droze

My condolences.

Tom what happened with ESS?

[Terraphantm]

Originally Posted by E91 M Sport

That's a common misconception. In normal use the oil's viscosity improvers actually thicken the oil as its temperature increased in order to maintain proper protection.

http://www.belray.com/what-exactly-d...ignations-mean

Virtually every oil gets thinner at higher temperatures. Viscosity improvers make it so that the a 0w-40 can act as a "0" at cold temperatures and a "40" at high temperatures. But the absolute viscosity at 260ºF will still be much less than at 210ºF, let alone cold engines. That "W" number only comes into play when it's cold. Once you get past 40ºC or so, the oil will behave more like a straight 40, or whatever rating oil you're using.

You can see some typical viscosity curves of various oil grades here: http://www.viscopedia.com/viscosity-...ine-oil/#c1290

The charts only go to 100ºC, but they won't suddenly reverse at 125ºC

[E91 M Sport]

Originally Posted by Terraphantm

Virtually every oil gets thinner at higher temperatures. Viscosity improvers make it so that the a 0w-40 can act as a "0" at cold temperatures and a "40" at high temperatures. But the absolute viscosity at 260ºF will still be much less than at 210ºC, let alone cold engines. That "W" number only comes into play when it's cold. Once you get past 40ºC or so, the oil will behave more like a straight 40, or whatever rating oil you're using.

So you agree, as the oil heats the viscosity improvers expand thus making the oil thicker.

[Terraphantm]

Originally Posted by E91 M Sport

So you agree, as the oil heats the viscosity improvers expand thus making the oil thicker.

No. Viscosity improvers change the viscosity curve so that for example a 0w can act like a "0" at low temperatures and a "40" at high temperatures. But that doesn't mean the oil is actually thicker at 260°F vs 200 (or any other low temperature). All those viscosity improvers do is make it so that the viscosity doesn't decrease *as quickly* with temperature as one would expect of a thin oil. And once you're past room temperature, that winter rating is pretty meaningless anyway.

The oil absolutely will be thinner at 260 vs 250 vs 240, 230, etc.

[E91 M Sport]

Originally Posted by Terraphantm

No. Viscosity improvers change the viscosity curve so that for example a 0w can act like a "0" at low temperatures and a "40" at high temperatures. But that doesn't mean the oil is actually thicker at 260°F vs 200 (or any other low temperature). All those viscosity improvers do is make it so that the viscosity doesn't decrease *as quickly* with temperature as one would expect of a thin oil. And once you're past room temperature, that winter rating is pretty meaningless anyway.

The oil absolutely will be thinner at 260 vs 250 vs 240, 230, etc.

It's funny cause we're on the same page but if you read the quote below it mentions how Viscosity improvers work. They expand thus increase viscocity when heated.

Now lets look at the high temperature test requirements, we will look at the 10W-30 again. The minimum viscosity of the 10W oil at 100C (212F) is 4.1 cSt. Now comes the chemistry magic. We need the 10W-30 oil to provide the high temperature viscosity of SAE 30 oil. The chemists use additives called viscosity improvers that expand as the temperature increases providing the viscosity necessary and when the temperature cools back down the viscosity improvers shrink

[hassmaschine]

no. that is only up to a point. The idea is you have a light oil when it's cold (0w) so that lubrication can get through the motor during startup. Once the oil warms up, the modifiers do increase viscosity to a point (normal operating temp).

However, definitely does NOT thicken at 260f. That is ridiculous. If it did, people would not run oil coolers - the truth is at high temps, not only can the oil itself break down (including additives), but the chain of molecules becomes stretched and the oil thins. This can result in low pressure which is dangerous for the engine especially if you are beating on it at the track.

[Terraphantm]

Originally Posted by E91 M Sport

It's funny cause we're on the same page but if you read the quote below it mentions how Viscosity improvers work. They expand thus increase viscocity when heated.

Here's the thing though: All that paragraph is saying is that compared to an "SAE 10" oil, a "10w-30" will be thicker at 100ºC compared to an SAE 10. It does *not* say that a 10w-30 will be thicker at 100ºC compared to the same 10w-30 at 50ºC (or even 99ºC).

Take a look at the spec sheet for this 5w40 oil: http://msdspds.castrol.com/bpglis/Fu...PXE-A5TQLE.pdf

Notice the Viscosity (kinematic) @ 40ºC and @100ºC.

At 40ºC, it's 84 cSt. And 100ºC it's 14.0 cSt. The oil is significantly thinner at 100ºC despite having viscosity improvers. That trend does not reverse (at least until the oil gets so hot that it starts undergoing chemical reactions and forms a different product altogether).

[E91 M Sport]

Originally Posted by E91 M Sport

That's a common misconception. In normal use the oil's viscosity improvers actually thicken the oil as its temperature increased in order to maintain proper protection.

Originally Posted by hassmaschine

However, definitely does NOT thicken at 260f. That is ridiculous. If it did, people would not run oil coolers - the truth is at high temps, not only can the oil itself break down (including additives), but the chain of molecules becomes stretched and the oil thins. This can result in low pressure which is dangerous for the engine especially if you are beating on it at the track.

Originally Posted by Terraphantm

Here's the thing though: All that paragraph is saying is that compared to an "SAE 10" oil, a "10w-30" will be thicker at 100ºC compared to an SAE 10. It does *not* say that a 10w-30 will be thicker at 100ºC compared to the same 10w-30 at 50ºC (or even 99ºC).

Take a look at the spec sheet for this 5w40 oil: http://msdspds.castrol.com/bpglis/Fu...PXE-A5TQLE.pdf

Notice the Viscosity (kinematic) @ 40ºC and @100ºC.

At 40ºC, it's 84 cSt. And 100ºC it's 14.0 cSt. The oil is significantly thinner at 100ºC despite having viscosity improvers. That trend does not reverse (at least until the oil gets so hot that it starts undergoing chemical reactions and forms a different product altogether).

I think where we turned to different pages is my initial comment where I stated normal use whereas you two are talking about extreme temperatures and I totally agree that oil can and will break down when pushed to its limits but up and to that point it does thicken to maintain proper lubricating abilities.

[hassmaschine]

no it does not. you must like arguing for the sake of arguing - but you are wrong.

[Terraphantm]

Originally Posted by E91 M Sport

I think where we turned to different pages is my initial comment where I stated normal use whereas you two are talking about extreme temperatures and I totally agree that oil can and will break down when pushed to its limits but up and to that point it does thicken to maintain proper lubricating abilities.

You have reading comprehension issues. Under normal conditions, oil will not thicken with increasing temperature, period. Doesn't matter what kind of viscosity improvers you have. It might only thicken if it starts to break down (and become sludge).

The only numbers I've referenced have been temperatures which engines see every day.