Just in case anyone cares

[johnd]

I hear a lot of talk about such and such an oil makes my car run quieter, noiser, etc. so I thought I'd do an experiment. I've been running Mobil one 10w30 for the last 6K mi (one yr.)and had decided to change to Havoline 10w30 and I wondered if the engine would sound any different. Here is the results:

Mobil 1
Sound pressure meter laying on the battery with the hood up, engine running. "C" Weighted (wide frequency response) fast response time, 84 Db.

Texaco Havoline
Same settings, same reading.

What exactly does this prove? Probably nothing, I suspect it was picking up alternator whine more than anything else, it is a really quiet engine, overall. But at least it is hard evidence. I welcome more data along these lines.

 

[ekpolk]

Neat experiment. Did you try it from inside the vehicle, with the hood down? I don't know whether or not the instrument you described would work like that, but I'd think it would give a better idea with respect to what some of us hear, or think we hear

, as we're driving on down the road. What type vehicle/engine do you have? Thanks for the interesting post.

 

[BrianWC]

And I was just thinking about how much quieter my car sounded with Pennzoil Platinum!

 

[G-MAN]

I think much of what an oil can do to "quiet" an engine is outside the scope of what a simple audio dB meter can read. Oil can affect NVH, of which audible sound is only one factor.

 

[TallPaul]

To really test the sound difference I think someone needs to run the test first with straight 50 and then with straight 10w. I think there would be a noticable difference.

 

[Gary Allan]

Good point TallPaul. Set your limits on the high/low

NVH

Neurotic Visceral Hysteria?? (n-something vibration harmonics

)

 

[johnd]

To clarify, the car is a 1997 Z28 Camaro with the 5.7 liter LT1 v8 engine. The meter was laying on the battery on it's side in the engine compartment with the hood up. It was left on and not touched until after the old oil was changed and the new added. The whole point of this is I was trying to rule out "subjective" and replace it with "objective" and the measurements show, at least in this case, that there was no difference. I come from a science background and I like hard data.

 

[TallPaul]

Ummmm...I wonder if old oil has different acoustics than new oil?

 

[GMorg]

Noise, Vibration, Harshness (NVH)...

 

[GoldenRod]

If you're trying to convince me to buy brand X1...... forget it.

 

[omaha]

pull the drivebelt first then do test. all other factors that oil connot effect will be gone

 

[ikeepmychevytoo]

You need unechoic acoustical chamber for measuring such small differences. I'm sure there'll be pickable differences either sonic or supersonic.

 

[widman]

I've replaced SAE 40 with 5w30 and you can hear the difference even with the radio on.
Not very scientific, but the way i figure it, it it isn't a diesel, it shouldn't sound like one.

 

[luvs2drive]

Well if you come from a scientific background, then you would probably have guessed that there are several frequencies at work here, and a simple dB meter cannot differentiate between them. It is likley that the low frequency signatures (combustion, exhaust pulses)is higher in amplitude and is drowning out the low amplitude high frequency ones (lifter actuation and piston skirt rattle etc.) which likley make up the noise variation caused by the oils dampening effect due to differences in viscosity. You'd need a audio spectral analyzer to separate out the varying frequencies to verify with any kind of serious accuracy.

Good start though!