[Mosaud1998]

I know this question might've been asked here before. But, would running 5W-40 oil in the B58 be harmful? On the hood, it states to run 0W-20. I don't feel comfortable running that thin oil even if I don't track the car.

I know 5W-40 weight oil offers better protection. That's why I'd rather run 5W-40 than 0W-20.

Would 5W-40 weight oil thicken up too much during the winter? I used 5W-40 in my E90. But the E90 required 5W-30. So, going from 5W-30 to 5W-40 wasn't a huge jump.

But, going from 0W-20 to 5W-40 is.

[OmahaDB]

I look at it this way... Am I more qualified to determine what oil is best for my engine, than the guys who designed, manufactured, support, and maintain that engine?

[Joe-BMW33]

I run Liqui Molly 01-5W-40 in my M550. I found that I had some consumption with the BMW 01-0W-30 spec and zero consumption with this. Credit to my performance shop that does my changes. I also do a ceratec flush every other change.

[Mosaud1998]

Originally Posted by Joe-BMW33

I run Liqui Molly 01-5W-40 in my M550. I found that I had some consumption with the BMW 01-0W-30 spec and zero consumption with this. Credit to my performance shop that does my changes. I also do a ceratec flush every other change.

That's another reason why I went with 5w-40 in the E90. Helped with oil consumption and lifter tick

[r1cero]

what makes you think that using oil that's not suited for your engine is better for it? if the consumption is lower that doesn't necessarily mean that it's better. 5w30 is usually more advanced and fullfils higher standards than 5w40 of course conditionally speaking.

[Mosaud1998]

Originally Posted by r1cero

what makes you think that using oil that's not suited for your engine is better for it? if the consumption is lower that doesn't necessarily mean that it's better. 5w30 is usually more advanced and fullfils higher standards than 5w40 of course conditionally speaking.

I think I'll go with 5W-30

[cna90]

A bit of my engineering knowledge. Take it for what it's worth.

Thinner oil helps better cool the engine than thicker oil cause they can get everywhere faster (higher flow, less pressure on the pump) and they can also flow better in tiny spots.

Specially if oil is not properly rated for the engine, it will damage the engine and pump in the long run. I wouldn't do anything higher than w30 on the new BMW engine due to lower tolerances on the parts. First number is just for the cold start temp to choose based on your local temps; weather 0w or 5w.
Here is a page from BMW manual:


You can top up with w40 up-to a liter only for b58 engine (540i) but you can use w40 for m550i as per manual/dealer but not recommended.

Longevity wise, thinner oil w20 helps your b58 (w30 for m550i) runs smoother and last longer due to lower tolerances and the way engine is designed in the new BMW. Also the engine oil sensor is calibrated for w20 on b58 and that will tell you exactly when to change based on your driving habits (sensor senses flow and temp).
Furthermore you shouldn't be loosing oil as this is a closed loop. If you do loose, there is leak somewhere or a point that the oil evaporates that needs to be fixed!!!
Adding a thicker oil reduce the amount you'd loose but not only doesn't solve the problem, it messes with your engine tolerances and oil pump.

[Joe-BMW33]

Oh goody, a classic Oil thread is forming. Making some popcorn now.

[cna90]

Originally Posted by Joe-BMW33

Oh goody, a classic Oil thread is forming. Making some popcorn now.

Haha. I've been looking at this for a few days. I kept myself out but somehow I had to dive in 😂😂😂

[Joe-BMW33]

Originally Posted by cna90

Haha. I've been looking at this for a few days. I kept myself out but somehow I had to dive in 😂😂😂

Hahaha, every time I see an oil debate beginning I think of this:

[Joe-BMW33]

Originally Posted by cna90

A bit of my engineering knowledge. Take it for what it's worth.

Thinner oil helps better cool the engine than thicker oil cause they can get everywhere faster (higher flow, less pressure on the pump) and they can also flow better in tiny spots.

Specially if oil is not properly rated for the engine, it will damage the engine and pump in the long run. I wouldn't do anything higher than w30 on the new BMW engine due to lower tolerances on the parts. First number is just for the cold start temp to choose based on your local temps; weather 0w or 5w.
Here is a page from BMW manual:




You can top up with w40 up-to a liter only for b58 engine (540i) but you can use w40 for m550i as per manual/dealer but not recommended.

Longevity wise, thinner oil w20 helps your b58 (w30 for m550i) runs smoother and last longer due to lower tolerances and the way engine is designed in the new BMW. Also the engine oil sensor is calibrated for w20 on b58 and that will tell you exactly when to change based on your driving habits (sensor senses flow and temp).
Furthermore you shouldn't be loosing oil as this is a closed loop. If you do loose, there is leak somewhere or a point that the oil evaporates that needs to be fixed!!!
Adding a thicker oil reduce the amount you'd loose but not only doesn't solve the problem, it messes with your engine tolerances and oil pump.

You make some great points and I am not even close to as knowledgeable as you when it comes to oil. I just trust my BMW Master Tech and he recommended 01LLF-5W-40.

But I somehow wonder, if the thinner oil is better, but it runs hotter and as a result, burns off. It has to be breaking down to burn off and you would think, impacting it's ability to lubricate?

OH BOY, here I go contributing to an oil debate. Pay no mind, I am ignorant on the subject. But I have spent years reading people go back and forth on the subject with extreme passion.

[Mosaud1998]

Originally Posted by cna90

A bit of my engineering knowledge. Take it for what it's worth.

Thinner oil helps better cool the engine than thicker oil cause they can get everywhere faster (higher flow, less pressure on the pump) and they can also flow better in tiny spots.

Specially if oil is not properly rated for the engine, it will damage the engine and pump in the long run. I wouldn't do anything higher than w30 on the new BMW engine due to lower tolerances on the parts. First number is just for the cold start temp to choose based on your local temps; weather 0w or 5w.
Here is a page from BMW manual:


You can top up with w40 up-to a liter only for b58 engine (540i) but you can use w40 for m550i as per manual/dealer but not recommended.

Longevity wise, thinner oil w20 helps your b58 (w30 for m550i) runs smoother and last longer due to lower tolerances and the way engine is designed in the new BMW. Also the engine oil sensor is calibrated for w20 on b58 and that will tell you exactly when to change based on your driving habits (sensor senses flow and temp).
Furthermore you shouldn't be loosing oil as this is a closed loop. If you do loose, there is leak somewhere or a point that the oil evaporates that needs to be fixed!!!
Adding a thicker oil reduce the amount you'd loose but not only doesn't solve the problem, it messes with your engine tolerances and oil pump.

I think I'm gonna go with 5W-30 my next oil change. I don't follow the sensor thing. I stick to 6 months or 5k intervals

[NGT2]

Originally Posted by cna90

Longevity wise, thinner oil w20 helps your b58 (w30 for m550i) runs smoother and last longer due to lower tolerances and the way engine is designed in the new BMW. Also the engine oil sensor is calibrated for w20 on b58 and that will tell you exactly when to change based on your driving habits (sensor senses flow and temp).

Just to clarify, are you saying thinner oil helps the engine last longer or just prolongs the oil change cycle?

I don't know jack about this topic. It just seems to me that BMW would recommend running the best oil for the engine, for several reasons. Can't think of a reason they'd want you to use any oil that was less than the best for the engine they built and stake their reputation on.

Joe - I totally understand trusting your BMW performance tech. My comment is more related to me making decisions for the car, not related to how I'd comply with an expert recommendation for my specific car.

[cna90]

Originally Posted by Joe-BMW33

You make some great points and I am not even close to as knowledgeable as you when it comes to oil. I just trust my BMW Master Tech and he recommended 01LLF-5W-40.

But I somehow wonder, if the thinner oil is better, but it runs hotter and as a result, burns off. It has to be breaking down to burn off and you would think, impacting it's ability to lubricate?

OH BOY, here I go contributing to an oil debate. Pay no mind, I am ignorant on the subject. But I have spent years reading people go back and forth on the subject with extreme passion.

Better is relative right.
Every oil no matter the rating (even the lifetime ones) breaks down over time under heat. In a closed-loop as you won't be losing any oil, you'd be changing under a certain time of operation which people use xxxx kms which is really xxxx hours of operations. This is because the ratio of the broken down oil and good oil in the system is degraded and below a certain limit beyond certain hours of operations.
Higher viscosity oil, can withstand higher temps than lower viscosity in theory, but it needs a higher flow rate and better cooling as well. If a system is designed for w20 as an example, it means, you don't have enough flow rate (not a big enough pump) for the higher grade oil and you're not doing a good job cooling it. This also means the wrong oil will degrade faster in the wrong environment.

These are all theories obviously. Manufacturers build a tolerance in the system especially with BMWs, since they usually upgrade more often than say Japanese lean engineering methods, to an over-performing rather than an underperforming cooling system.
Looking at most Toyotas and Hondas they run w20 because they have perfected manufacturing tolerances over the years by using older techs to be more reliable hence the clean oil you get every time you oil change a 10-year-old Toyota.

lol I can't stop..

[cna90]

Originally Posted by NGT2

Just to clarify, are you saying thinner oil helps the engine last longer or just prolongs the oil change cycle?

I meant the engine but as the system is built for the thinner oil (w20 for b58), thinner oil will last longer as well.
Thicker oil needs a bigger cooling system and/or a higher flow rate pump to perform identically.

[Mosaud1998]

Originally Posted by cna90

Better is relative right.
Every oil no matter the rating (even the lifetime ones) breaks down over time under heat. In a closed-loop as you won't be losing any oil, you'd be changing under a certain time of operation which people use xxxx kms which is really xxxx hours of operations. This is because the ratio of the broken down oil and good oil in the system is degraded and below a certain limit beyond certain hours of operations.
Higher viscosity oil, can withstand higher temps than lower viscosity in theory, but it needs a higher flow rate and better cooling as well. If a system is designed for w20 as an example, it means, you don't have enough flow rate (not a big enough pump) for the higher grade oil and you're not doing a good job cooling it. This also means the wrong oil will degrade faster in the wrong environment.

These are all theories obviously. Manufacturers build a tolerance in the system especially with BMWs, since they usually upgrade more often than say Japanese lean engineering methods, to an over-performing rather than an underperforming cooling system.
Looking at most Toyotas and Hondas they run w20 because they have perfected manufacturing tolerances over the years by using older techs to be more reliable hence the clean oil you get every time you oil change a 10-year-old Toyota.

lol I can't stop..

Intrestinfg topic imo.

[Joe-BMW33]

Originally Posted by NGT2

Just to clarify, are you saying thinner oil helps the engine last longer or just prolongs the oil change cycle?

I don't know jack about this topic. It just seems to me that BMW would recommend running the best oil for the engine, for several reasons. Can't think of a reason they'd want you to use any oil that was less than the best for the engine they built and stake their reputation on.

Joe - I totally understand trusting your BMW performance tech. My comment is more related to me making decisions for the car, not related to how I'd comply with an expert recommendation for my specific car.

Oh trust me, I get the query. I've just seen so many debates about oil. I am kind of in the camp that it's oil. Use a quality brand and change it a lot.

[Joe-BMW33]

Originally Posted by cna90

Better is relative right.
Every oil no matter the rating (even the lifetime ones) breaks down over time under heat. In a closed-loop as you won't be losing any oil, you'd be changing under a certain time of operation which people use xxxx kms which is really xxxx hours of operations. This is because the ratio of the broken down oil and good oil in the system is degraded and below a certain limit beyond certain hours of operations.
Higher viscosity oil, can withstand higher temps than lower viscosity in theory, but it needs a higher flow rate and better cooling as well. If a system is designed for w20 as an example, it means, you don't have enough flow rate (not a big enough pump) for the higher grade oil and you're not doing a good job cooling it. This also means the wrong oil will degrade faster in the wrong environment.

These are all theories obviously. Manufacturers build a tolerance in the system especially with BMWs, since they usually upgrade more often than say Japanese lean engineering methods, to an over-performing rather than an underperforming cooling system.
Looking at most Toyotas and Hondas they run w20 because they have perfected manufacturing tolerances over the years by using older techs to be more reliable hence the clean oil you get every time you oil change a 10-year-old Toyota.

lol I can't stop..

Got it! Thanks for the comprehensive and well written reply. I appreciate you laying this out. Maybe I am going to W30 next time. Last question, so what does the 0 vs. the 5 mean before the W?

[MauiSteve]

The thinner 0W-20 oil likely more effectively penetrates to lubricate the tight space between bearing and crankshaft. I think you must all know about the history of BMW engines and rod bearings. If engineers have specified 0W-20 for the B58 manufacturing tolerances then you ought to stick to that or you may cause premature wear to your engine.

[Joe-BMW33]

Originally Posted by MauiSteve

The thinner 0W-20 oil likely more effectively penetrates to lubricate the tight space between bearing and crankshaft. I think you must all know about the history of BMW engines and rod bearings. If engineers have specified 0W-20 for the B58 manufacturing tolerances then you ought to stick to that or you may cause premature wear to your engine.

I don't have the B58 if you are talking to me. I believe 0w-30, 0w-40, 5w-30 or 5w-40 are all referenced as acceptable choices for the N63TU2/3, per BMW. I am going to get a Blackstone analysis at the next change. Not that I would understand any of it!

[OmahaDB]

Originally Posted by Joe-BMW33

I don't have the B58 if you are talking to me. I believe 0w-30, 0w-40, 5w-30 or 5w-40 are all referenced as acceptable choices for my car, per BMW. I am going to get a Blackstone analysis at the next change. Not that I would understand any of it!

What I like about Blackstone is that they give you some pretty good commentary on the results. We send a sample off every time we change oil in the airplane. Over time you get a good picture of how your engine is doing, as well as whether your oil change interval is about right.

In our case, we fly behind a Rotax 912ULS. The "conventional wisdom" you hear often hear is to change oil every 50 hours (25 hours if you're running mostly leaded AVGAS), but a more careful reading of the maintenance schedule reveals that the factory specified interval is actually 100 hours if you're using mostly or all MOGAS as we do. When I switched to a 100 hour oil change interval, I was initially cautious and skeptical - the Blackstone analysis bore out the fact that the oil was in fact just fine.

A single sample is informative, but not ideal. Ideally you do it every time, and watch the trends over time. It can tell you in advance when you've got things starting to look like they might cause trouble.

[MauiSteve]

Originally Posted by Joe-BMW33

I don't have the B58 if you are talking to me. I believe 0w-30, 0w-40, 5w-30 or 5w-40 are all referenced as acceptable choices for the N63TU2/3, per BMW. I am going to get a Blackstone analysis at the next change. Not that I would understand any of it!

My response was not directed at you, but rather to the OP and overall thread in general.