Decibel Reading After Switching Oil Brands

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I don't know how scientific this is but check this out. I have a decibel meter app on my phone. I got home, parked my LS400 in the driveway, left it idling and placed my phone directly on top of the intake. The meter bounced between 53-55 at idle.

I changed oil to a different brand and drove my LS400 about 6 miles and got it warmed up. Parked in the driveway and following the same procedure I got a reading of between 50-52 decibels.

This wasn't some emotionally guided response trying to prove one oil is better or quieter than another. Same phone, same location, same car, etc.

Looks to me that a quieter idling engine is better. Am I wrong? Seems to me the quieter oil would be better for my engine. Oh, same viscosity in that they are both 5w30's.
 
Originally Posted By: Gebo
I don't know how scientific this is but check this out. I have a decibel meter app on my phone. I got home, parked my LS400 in the driveway, left it idling and placed my phone directly on top of the intake. The meter bounced between 53-55 at idle.

I changed oil to a different brand and drove my LS400 about 6 miles and got it warmed up. Parked in the driveway and following the same procedure I got a reading of between 50-52 decibels.

This wasn't some emotionally guided response trying to prove one oil is better or quieter than another. Same phone, same location, same car, etc.

Looks to me that a quieter idling engine is better. Am I wrong? Seems to me the quieter oil would be better for my engine. Oh, same viscosity in that they are both 5w30's.


Those differences are so small you can't draw any conclusions from them-IMHO. Your phone (the app aside) is not a scientific sound measuring device.

Useless thread.....
 
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Fresh oil vs. used oil probably accounts for the difference.
21.gif
 
Perhaps not a scientific device but if the same device is used throughout and conditions are the same for each reading, it would give us a general idea or a trend would it not?
 
Originally Posted By: PimTac
Perhaps not a scientific device but if the same device is used throughout and conditions are the same for each reading, it would give us a general idea or a trend would it not?


Sort of my thinking.
 
If you had breathed on it while it was running, you would have raised the decibel level from 50 to 53.. if not more.

Moderate rainfall is 50dB, and normal human conversation is 55dB. Leaves rustling/calm breathing is 15dB.

Personally, I would consider a change from 50-52 to 53-55 (or vice-versa) just statistical noise.


slvls.jpg
 
Originally Posted By: Gebo
Originally Posted By: PimTac
Perhaps not a scientific device but if the same device is used throughout and conditions are the same for each reading, it would give us a general idea or a trend would it not?


Sort of my thinking.

+1
 
Originally Posted By: CharlieW618
Fresh oil vs. used oil probably accounts for the difference.
21.gif


i believe this hypothesis.
When oil is put into service it is different than after it's been heated cycled a few times.
Try your reading again in a week, and every week and track the results through the next oil change.
 
Originally Posted By: raytseng
Originally Posted By: CharlieW618
Fresh oil vs. used oil probably accounts for the difference.
21.gif


i believe this hypothesis.
When oil is put into service it is different than after it's been heated cycled a few times.
Try your reading again in a week, and every week and track the results through the next oil change.





This idea has merit.
 
The idea is 110% valid. Fluid dynamics or acoustic theory is literally what you are describing.

However, the idea that an engine oil that has a quieter acoustic property creates less wear has never been proven. In many cases the oil with a poorer acoustic property was shown to have better wear properties. Meaning the acoustic property is not reflective of the wear properties.
 
Originally Posted By: SirTanon
If you had breathed on it while it was running, you would have raised the decibel level from 50 to 53.. if not more.

Moderate rainfall is 50dB, and normal human conversation is 55dB. Leaves rustling/calm breathing is 15dB.

Personally, I would consider a change from 50-52 to 53-55 (or vice-versa) just statistical noise.


slvls.jpg



No you wouldn't dB is a logarithmic scale.

going from 3dB to 6dB is doubling the sound Pressure...6dB to 9dB is double again, i.e. 4 times the sound pressure.

Breathing on a 3dB source makes a huge difference, breathing on a 50dB source is nothing...approximately 1 part in 4,000 in terms of sound pressure, 52dB becomes 52.01 if you get the drift.

As to the OP's issue, here's some actual testing from a paper I found ages ago...
 
Some engines made a noise difference for the better (noise), others no difference.

My 3VZE in a 4Runner ages ago rattled like a tine bucket of marbles on M1 0W40...you can probably find my comments pre dating "noisy M1" threads...not saying that was probably the most universally superior lube at the time was causing any more wear, I just didn't like it.
 
Originally Posted By: Shannow
going from 3dB to 6dB is doubling the sound Pressure...6dB to 9dB is double again, i.e. 4 times the sound pressure.

Yep, to add OP basically saw a 3 dB decrease in noise which is half as loud - results similar to the table you posted. Half as loud starting at 53 dB isn't real noticable to the ear (depends on the person), but a 3 dB decrease in say a gun shot that's originally at 140 dB is very noticeable.

Would be interesting to see if the OP's engine sound level changes with mileage on the oil.
 
Originally Posted By: PimTac
Perhaps not a scientific device but if the same device is used throughout and conditions are the same for each reading, it would give us a general idea or a trend would it not?

Yes, using the same device and conditions helps. Though for noise readings, you'd have to make sure air temperature, pressure, and humidity were the same.

As for the fact that it's not "a scientific device", I'm not sure most people here know what that really means. But either way, that doesn't necessarily invalidate the result.

The biggest unknown here is precision. In other words, if you do exactly the same measurement of exactly the same thing with the same device over and over, are you going to get the same result every time? Are all your measurements going to be within 1 dB of each other? 0.1 dB? 0.01 dB? Devices meant for real scientific work have high precision, meaning the numbers will be the same every time within a very small margin. Their precision will also be similar in different measurement ranges, so the margin of error is always more-or-less "x" whether you're looking at 20 dB or 120 dB, for example. But more importantly, they have known precision -- in other words, the manufacturer knows how much the measurement will vary each time in any given range, and they share that info with you the user so that you can figure out how to compensate with repetition and/or other instruments.

If the phone with its app were precise to within 0.01 dB in the 50-60 dB range, it's highly unlikely that a 3dB change is a fluke, so we wouldn't need a heck of a lot of repetition, and interpreting the results would be easy. On the other hand, if it were only precise to within 5 dB in that range, we'd need a lot of repetition, and more statistical math might be necessary to interpret the results. If we don't know, we should assume the precision is low.
 
One thing we need to validate this test is to check at the time of the next oil change....fresh oil vs fresh oil.
 
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