Decibel Reading After Switching Oil Brands

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Originally Posted By: CKN
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.....


I'm with you on this one. A phone app decibel meter, and such a small difference I doubt you can draw conclusions. OTOH IMO if the difference is loud enough for a human to hear, as many of us have witnessed, then there's something going on and worthy of further investigation.
 
I'm gonna check it periodically over the next OCI. I'll let you know.
 
I know you younger guys aren't going to believe this but way back when before A/V receivers came with the little mic you put in the listening position to adjust the volume of each channel we had to do this manually. Being the A/V geek I was I went to Radio Shack and bought a dedicated db meter. Long story short is even in a somewhat controllable environment it was hard to get the same reading twice so I can imagine being out side would be even worse.

But I find this interesting and hope the OP does more testing. I may have to see if I can find that old meter.
 
Originally Posted By: Shannow




As to the OP's issue, here's some actual testing from a paper I found ages ago...



OK, noise goes down with more viscous, fresh oil after 15 mins of run time. That seems consistent with viscosity increase as the cause, either by reducing metal-metal contact/impacts, and/or by deadening any sound produced. Not very surprising.

Why does it go down further after a week? That does seem surprising.

(I'm assuming it was at operating temperature for the 15 minute sample, otherwise it isn't a very good time point for a reading)
 
Originally Posted By: Gebo
I'm gonna check it periodically over the next OCI. I'll let you know.


I was just going to suggest this, should be interesting.
 
Last edited:
Originally Posted By: PimTac
A lot of these decibel apps will give an average over the time measured.


Everything is an average over the time measured...even a "peak" has a time interval.
 
Originally Posted By: danielLD
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.



Early on, I was taught to question the veracity of anyone espousing values above 100%.

Are you a fisherman?
 
The following is true.
I once purchased 6 cases of a particular oil on clearance. That oil found it's way into 4 different vehicles and some OPE.
EVERYONE commented that their engines were quieter.
That PROVES it!
Didn't take any measurements though. DANG.
 
Originally Posted By: Kira
The following is true.
I once purchased 6 cases of a particular oil on clearance. That oil found it's way into 4 different vehicles and some OPE.
EVERYONE commented that their engines were quieter.
That PROVES it!
Didn't take any measurements though. DANG.

Exactly. The following is also true.
I once changed oil for a widower in our neighborhood who died about a month later. NO ONE commented that what I did contributed to his death however.
I didn't ask any questions.
 
Originally Posted By: kschachn
Originally Posted By: Kira
The following is true.
I once purchased 6 cases of a particular oil on clearance. That oil found it's way into 4 different vehicles and some OPE.
EVERYONE commented that their engines were quieter.
That PROVES it!
Didn't take any measurements though. DANG.

Exactly. The following is also true.
I once changed oil for a widower in our neighborhood who died about a month later. NO ONE commented that what I did contributed to his death however.
I didn't ask any questions.


Something very similar happened to me when I changed my elderly neighbors oil in his Olds 98.

Have you just identified a previously unnoticed connection?
 
You would have to look at a spectrum analyzer and look at harmonics. Odd harmonics are typically BAD noises for engines to make.

Placing a recording phone/device on the subject that is vibrating if poor practice as minor placement differences will evidence varied reading due to transferred vibrations and phase cancellation.

My car is making some bad noises now at the end of its OCI, hopefully the addition of a new filter some Magnatec or QSUD 10w30 will fix that
smile.gif
At this stage in following (my) engine's noise I tend to blame bad fuel 1st, then the filter eventually clogging with gum, next.
 
Originally Posted By: ArcticDriver
Originally Posted By: kschachn
...
I once changed oil for a widower in our neighborhood who died about a month later. NO ONE commented that what I did contributed to his death however.
I didn't ask any questions.


Something very similar happened to me when I changed my elderly neighbors oil in his Olds 98.

Have you just identified a previously unnoticed connection?


Probably should just use conventional in these cases
 
I did take a black magic marker and mark every side of my phone so it could get my phone back in the exact same place it was before
 
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.


prolly has nothing to do with the oil: - your cars AC was 'working harder' on first reading (accounting for higher numbers);
It didn't have to 'work as hard' later in the day with cooler temps - lower numbers ...
 
I've got a Quest prof sound level meter, in a quiet room with everything turned off,
I can't get a level below 35dB. That's entirely normal.

To measure leaves rustling at 15dB, it won't be a direct measurement since there's plenty
of wide-band background noise we take for granted and ignore.

Way back there was a calculation we had to use for noise of equipment that took into account
background noise and then the equipment on for a true value.

Sound is a funny thing, it's very non-linear, as in logarithmic!
smile.gif
 
It is quite obvious that the oil change got rid of the microscopic pieces of metal that were bouncing around inside the engine and making scratching noises.
 
Originally Posted By: ZZman
It is quite obvious that the oil change got rid of the microscopic pieces of metal that were bouncing around inside the engine and making scratching noises.


LOL
 
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