Horsepower VS Oil Change Interval (OCI)

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We come to this forum because we care about extending the life of engines and transmissions, and at the same time trying to save the earth (and money) by not throwing away good engine oil which can continue to be in service. With that out of the way, If a used oil of 3000 miles has similar wear metals, similar viscosity to the same 5000 miles oil, which I see it in a lot of UOAs, does it mean the same engine should output the same maximum power on both mileages? UOAs here showing people running their oil for more than 5000 miles. Although a lot of you have good results with it, does anyone here also did a dyno run, quarter mile run, in gear acceleration time... of different mileage on the same oil along with a UOA report? I’m trying to see if there’s any relationship between Engine Power vs Mileage/Time on the oil. So maybe we can all decide to change our oil based on quarter mile time, 0-60 time, in gear acceleration times, dyno run… without spending money to buy the kit from the oil analysis lab. But I believe new oil got to be more horsepower than 5000 mile oil, right?
 
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Not trying to be a smart-aleck, but I'd much rather do UOA's than try to make a calculation. A calculation would only tell you what your oil should be doing.
 
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Originally Posted By: jon_a_127
But I believe new oil got to be more horsepower than 5000 mile oil, right?
Why? Belief (religion aside) should be based on evidence, or at least a rationale. I can't see either for that belief. Any effects are likely to be so tiny as to be un-measurable, but if the used oil has sheared down the lower viscosity MIGHT allow the engine to develop more usable power.
 

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Originally Posted By: Ducked
Originally Posted By: jon_a_127
But I believe new oil got to be more horsepower than 5000 mile oil, right?
Why? Belief (religion aside) should be based on evidence, or at least a rationale. I can't see either for that belief.
Because new oil isn't dark in color, but 5000 mile oil is. Dark color engine oil holds dirty contaminants, combustion by-products. That can't be good for lubrication, right? hence resulting in less lubricity.
 
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The viscosity of new oil falls during use until the detergent additives have been used up, which in a normal OCI should not happen. That means for a typical 5K mile OCI that the max power figure should be a fraction higher if the engine is in good order.
 
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Originally Posted By: jon_a_127
But I believe new oil got to be more horsepower than 5000 mile oil, right?
I believe just the opposite is true. Oil typically thins out throughout the course of a typical OCI, and thoretically thinner oil should result in higher HP, albeit the difference would be very minimal.
 
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Originally Posted By: jon_a_127
But I believe new oil got to be more horsepower than 5000 mile oil, right?
There's absolutely no fundamental scientific reason for that to be true, so long as all the additive levels are still good and most oils have sufficient levels for FAR more than 5k mile OCIs. Furthermore, change in viscosity is going to have FAR more effect than any hypothetical change in the oil's ability to lubricate due to normal levels of additive depletion and contaminant loading, and viscosity tends to go DOWN (less power robbed) until oxidation thickening becomes dominant very, very late in the oil's useful life.
 
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OK, so multi's shear down with age (for a while) so you should see an infinitesimally small gain as the oil thins... Then they start to build oxidation by-products which thicken oil. So that gain will be going away. the trick is to get the old oil out before oxidation thickening can occur to any great degree... You pick the mileage when that will happen in any particular engine...
 
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I have run many engines in the 550 to 950 HP range on the engine dyno. The variations from run to run are enough to make it difficult to see very small variations in output. I dont think that new vs. used oil of the exact same type would show enough significance in a dyno run to be significant. In some break in runs on the dyno I have changed the oil before proceeding to the power runs. I didn't really notice anything, but I wasn't looking for changes due to oil, as well as the oil was only 2 hours old. Im sure it makes some difference, but probably not much and Im not even sure if it would be a gain or loss of power. I have learned that almost everything can make a change in output. But until you test it you dont actually know if it is a gain or loss and how much.
 
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Oil cannot produce horsepower. Too thick an oil will limit output by increasing frictional losses. And too thin of an oil can allow loss of pressure past the rings. But....With any suitable oil in the crankcase, for any reasonable OCI, the difference in actual engine output would not be more than a percentage point or two.
 
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One of the most useful engineering tools is signal to noise ratio. In the case of trying to determine the oil quality by looking at the engine horsepower output, compared to doing a used oil analysis you would be taking a giant step in the wrong direction with respect to signal to noise ratio. There are just too many things (noise) that can cause problems in what you are looking at, and the signal (the small amount of HP change) is too small for it to show the results you are looking for.
 
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