0W20 vs 5W30 in 1999 E46 323i

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Originally Posted By: CATERHAM
Originally Posted By: Garak
Well, if I was driving it from a cold start for about a mile, and then shutting it down for hours, and repeating, I'm sure a 20 grade would be harmless. Outside of that, stick with something of specified viscosity.

Better than "harmless", it would provide superior lubrication.


OK, define "superior"

References ?

Any evidence of this in industry standard wear tests like the sequence IVA ?
 
Originally Posted By: Garak
Well, if I was driving it from a cold start for about a mile, and then shutting it down for hours, and repeating, I'm sure a 20 grade would be harmless. Outside of that, stick with something of specified viscosity.


Problem is that you can't absolutely predict what's going to happen through the OCI...it may one day be called upon to drive across the continent to attend a funeral, when the orignal "duty" was 2 mile commutes in the cold.

More reason to install what the OEM considers as appropriate rather than second guessing the engineer's intentions.
 
Originally Posted By: Shannow
Originally Posted By: Garak
Well, if I was driving it from a cold start for about a mile, and then shutting it down for hours, and repeating, I'm sure a 20 grade would be harmless. Outside of that, stick with something of specified viscosity.


Problem is that you can't absolutely predict what's going to happen through the OCI...it may one day be called upon to drive across the continent to attend a funeral, when the orignal "duty" was 2 mile commutes in the cold.

More reason to install what the OEM considers as appropriate rather than second guessing the engineer's intentions.


Well that's your fear mongering, belt and suspenders mind set at play that can't even allow someone to have fun with the topic.
Of course from your perspective it's perfectly okay to run a 15W-50 in a late model GM V6 because everybody knows "thicker oil keeps the bearing further apart".
 
Originally Posted By: CATERHAM
Of course from your perspective it's perfectly okay to run a 15W-50 in a late model GM V6 because everybody knows "thicker oil keeps the bearing further apart".


Still telling that lie...good work.
 
And are you saying that it DOESN'T keep the bearings further apart ?


Clearly you don't grasp the concept

Originally Posted By: Shannow
Originally Posted By: CATERHAM

Better than "harmless", it would provide superior lubrication.


OK, define "superior"

References ?

Any evidence of this in industry standard wear tests like the sequence IVA ?


You missed a bit
 
Originally Posted By: Shannow
And are you saying that it DOESN'T keep the bearings further apart ?


Probably not, maybe. Who says further apart is better. The moving surfaces should not touch.

Engine bearings are different from a turbine shaft that floats.
 
turtlevette, being an engineer yourself you would understand what the Stribeck curve is, and means.

"Floats"...that's a new one, implies buoyancy, which clearly isn't there.
 
Originally Posted By: Shannow
"Floats"...that's a new one, implies buoyancy, which clearly isn't there.


Floats is descriptive. When a boat is on plane is it floating?
 
When it's static, stationary, it is floating...buoyancy.

When it is on a plane, it's sitting higher...what causes that ?

hydrodynamics, but you already know that with your trick questions.
 
Originally Posted By: turtlevette
Who says further apart is better. The moving surfaces should not touch.


Stribeck curve...
image7.jpg


You don't know, I don't know, and CATERHAM doesn't know where on the curve the BMW engineers set their operational parameters...they clearly agree that the moving surfaces should not touch, but where to the right of not touching they are, we just don't know.

They have designed in a safety factor "belt and braces" as some call it...we don't know how big that happens to be.

To unilaterally declare that viscosity can be lowered over what the OEM says is arbitrary, and not science based...lack of blow-ups is not science.
 
Originally Posted By: CrawfishTails
BMW conservatism aside, there is really nothing special or different that sets BMW engines apart from GM, Ford, Chrysler, Mazda, Honda, Toyota technology where low-HTHS oils are used all the time for everyday driving.


BMW engines usually have piston oil squirters, and most regular cars do not. The oil runs MUCH hotter when it's being used to cool the piston. And BMWs of that era, at least, usually didn't have an oil cooler.

My 2000 BMW with an S52 engine has piston oil squirters and no oil cooler. Typical highway oil temp is 210-240, depending on my right foot.

I would think that performance engines with their stiffer valve springs would heat up the oil more as well. More friction. RPM matters, too (performance cars are usually geared to rev more than, say, a Camry).
 
Originally Posted By: Shannow
Originally Posted By: turtlevette
Who says further apart is better. The moving surfaces should not touch.


Stribeck curve...
image7.jpg


You don't know, I don't know, and CATERHAM doesn't know where on the curve the BMW engineers set their operational parameters...they clearly agree that the moving surfaces should not touch, but where to the right of not touching they are, we just don't know.

They have designed in a safety factor "belt and braces" as some call it...we don't know how big that happens to be.

To unilaterally declare that viscosity can be lowered over what the OEM says is arbitrary, and not science based...lack of blow-ups is not science.

Yes the engineers do know and it goes beyond the specified oil grade. The lower the maximum oil temp's the higher up the Stribeck curve; hence the lower the oil grade you can run while maintaining the same viscosity reserve. Which is why before the advent of 0W/5W-30/40 synthetic oils manufacturers specified lighter oil grades for lower ambient operating temp's.

And the safe minimum oil pressure spec' available from the manufacturer or engine tuner can be used as a proxy for operational viscosity and is an even better tool than just ambient temp's or even just oil temp's for knowing what is the safe minimum viscosity to maintain and gives the bottom line taking into account oil temp's, oil grade, oil shear and fuel dilution.
 
Originally Posted By: Skid
Originally Posted By: CrawfishTails
BMW conservatism aside, there is really nothing special or different that sets BMW engines apart from GM, Ford, Chrysler, Mazda, Honda, Toyota technology where low-HTHS oils are used all the time for everyday driving.


BMW engines usually have piston oil squirters, and most regular cars do not. The oil runs MUCH hotter when it's being used to cool the piston. And BMWs of that era, at least, usually didn't have an oil cooler.

My 2000 BMW with an S52 engine has piston oil squirters and no oil cooler. Typical highway oil temp is 210-240, depending on my right foot.

I would think that performance engines with their stiffer valve springs would heat up the oil more as well. More friction. RPM matters, too (performance cars are usually geared to rev more than, say, a Camry).

Many vehicles including Bimmers, at least the normally aspirated ones including M series cars, have oil temp's that are affected very much by ambient temp's. Any Bimmer owner with an oil temp' gauge equipped car operating a sub-freezing temp's can attest to this. This is due in large part to the exposed finned aluminium sump which makes it a struggle to reach even low normal operating temp's of even 80C.
So yes if you're running continuously for months on end in a cold climate you can certainly benefit from running a 0W-20. Of course having oil gauges is best to monitor things if you're going to deviate markedly from the lightest oil specified by the manufacturer.
 
Originally Posted By: Shannow
Originally Posted By: CATERHAM

Better than "harmless", it would provide superior lubrication.


OK, define "superior"

References ?

Any evidence of this in industry standard wear tests like the sequence IVA ?


Sorry CATERHAM, you seem to have missed a bit...again
 
Originally Posted By: BigmanXD
Hello everyone I'm brand new to the forum and have been looking for my topic on the forums and haven't been able to find it so forgive me if this is already a topic. However, after completing the BOTOG university and coming to the conclusion that thinner oil is better especially after reading http://www.bobistheoilguy.com/motor-oil-105/ I'm still unsure about it. I currently own a 1999 BMW 323i E46 with 193,456 miles without any oil leaks or consumption that has been babied its whole life with synthetic oil and no mechanical problems what so ever. I live in Florida where the average temperature is pretty high and was wondering if it would be totally fine running a 0W20 in a car that the owners manual recommends a synthetic 5W30. Finally, if the 0W20 is ok to use in my vehicle can the same be said to all vehicles recommending 5W30 if they have been babied like mine. Thanks for your help!

Bigman


The misunderstandings...

Again, Haas never said "thinner was (always) better". I believe he was only talking about new or newer engines, Haas actually recommended thicker viscosity in aging, higher mileage engines...
 
Originally Posted By: CATERHAM
So yes if you're running continuously for months on end in a cold climate you can certainly benefit from running a 0W-20. Of course having oil gauges is best to monitor things if you're going to deviate markedly from the lightest oil specified by the manufacturer.


But my point is that this the requires everyone who is operating the car to understand the limitations of what's in the sump...and not take it on the emergency funeral run without doing an oil change.

My Caprice has a big winged alloy sump, and still hits 105C oil temperatures (type K thermocouple dropped down the dipstick) when it's freezing, in as little as 20km on the highway. (before you start, that's a 3.2cst HTHS 5W30)

As an example of my argument, I'll use something that you are familiar with, the owner's manual of the Nissan 510.
5106973.jpg


Clearly, 5W20 was acceptable (not a recommendation) at continuous operation at ridiculously low maximum temperatures. It's similar to your assertion in this thread.

SAE40 was acceptable (not a recommendation) at continuous operation at ridiculously high temperatures...reverse argument to yours, but still applicable.

But the Goldilocks recommendation (and I say that because it's at the top of the list and covers all of the temperature ranges) was 10W30, which rather than being you "belt and braces", was just more suitable for "normal" people, doing normal stuff with their cars, all year round.
 
Originally Posted By: Nickdfresh
Originally Posted By: BigmanXD
Hello everyone I'm brand new to the forum and ................ and coming to the conclusion that thinner oil is better especially after reading http://www.bobistheoilguy.com/motor-oil-105/ I'm still unsure about it. .......................... running a 0W20 in a car that the owners manual recommends a synthetic 5W30.

Bigman


The misunderstandings...

Again, Haas never said "thinner was (always) better". I believe he was only talking about new or newer engines, Haas actually recommended thicker viscosity in aging, higher mileage engines...


Regardless what our Doc H. or BITOG Uni 101????? recommends its the vehicle manufacturers recommendation for the thinnest grade that should be adhered to and your reference manual IMO.

The Doc conducts UOAs liaises with manufacturer and in my view is a unique example perhaps not for others to follow unless you are prepared to follow the same regime ie UOA record monitor, liaise with industry etc.

Departure from OEM guidelines should be on a case by case basis by the owner rather than imply the experience of some individuals practice is acceptable across the board.

I think I need to take break I am getting tired of repeating myself with references back OEM ..............
 
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Originally Posted By: fdcg27
BMW dealers offer a BMW-branded Castrol 5W-30 that meets BMW's specs.
It isn't the same oil as the 5W-30 syns sold at Walmart.
It's an A3 oil, with HTHS viscosity of at least 3.5.
If it were my car and I wanted to save a few bucks, I'd use a blend 10W-40 like Maxlife or Defy and change it at conservative intervals.
If I wanted to use the correct oil, M1 0W-40 is only a ten spot or so more expensive than either of the above at Walmart and can be run longer.
You live in a place where winter is little more than something that happens in the north. There is no advantage to your engine in using thinner than recommended oils and there might be real consequences.



Actually, thats exactly what I run in my cars - Maxlife 10W-40 for the past ~60k miles with 5-7k OCI's. My oil consumption is 0.

My track car, however, will get Edge 5W-50. Partly because I have about 40 quarts of it sitting on a shelf.
 
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Originally Posted By: Shannow
Originally Posted By: CATERHAM
So yes if you're running continuously for months on end in a cold climate you can certainly benefit from running a 0W-20. Of course having oil gauges is best to monitor things if you're going to deviate markedly from the lightest oil specified by the manufacturer.


But my point is that this the requires everyone who is operating the car to understand the limitations of what's in the sump...and not take it on the emergency funeral run without doing an oil change.

My Caprice has a big winged alloy sump, and still hits 105C oil temperatures (type K thermocouple dropped down the dipstick) when it's freezing, in as little as 20km on the highway. (before you start, that's a 3.2cst HTHS 5W30)

As an example of my argument, I'll use something that you are familiar with, the owner's manual of the Nissan 510.
5106973.jpg


Clearly, 5W20 was acceptable (not a recommendation) at continuous operation at ridiculously low maximum temperatures. It's similar to your assertion in this thread.

SAE40 was acceptable (not a recommendation) at continuous operation at ridiculously high temperatures...reverse argument to yours, but still applicable.

But the Goldilocks recommendation (and I say that because it's at the top of the list and covers all of the temperature ranges) was 10W30, which rather than being you "belt and braces", was just more suitable for "normal" people, doing normal stuff with their cars, all year round.

I thought my explanation of operational viscosity was pretty clear.
To repeat, those old viscosity/ambient temperature charts are a very crude way of telling the operational viscosity story without any reference to oil temp's or oil pressure.
If you know your oil temp's then ambient temp's don't matter once you know the safe maximum oil temp's for an oil grade but oil pressure is the real bottom line. Once you know what the established safe minimum value is at some elevated reverenced rpm you're in total control.

Fast forward to the present time when generally just one oil grade is recommended for year round use. If that recommended grade is say an A3/B4 5W-30, in an OP and OT equipped vehicle on that spec' oil, the owner will be able to establish under all driving and climatic conditions just how much viscosity reserve is present. With that knowledge one may come to the conclusion that running something lighter might still allow a more than adequate viscosity reserve year round or perhaps just during the winter months.
Once one is totally familiar with the OP and OT of their car there really is no risk in running an oil that is too light, on the contrary if something out of the ordinary happens that could significantly lower the operational viscosity (oil pressure), such as a leaking fuel injector causing fuel dilution, you'll know it immediately and can take remedial action. If it's unusually high oil temp's as a result of trailer towing in a heat wave, you'll know it and can modify you're driving behaviour accordingly.
The point is you're in control of how much viscosity reserve you're comfortable with.
 
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