Old Oil Better

[Ironhorseman]

A base can be corrosive, just like an acid. As the oil's base additives are depleted, the PH is lowered. The closer to a PH of 7 you get, the less corrosive wear you see on metal.

This might not be the whole picture, but it's part of it.

 

[TooSlick]

My understanding is that the activation temp of ZDDP is about 75C or 167F. The previously formed, AW films on wearing surfaces are thus depleted during engine warmup. However cold oil is much thicker and so you tend to have full flow lubrication as soon as full oil pressure is reached.

As the oil thins out, the ZDDP also becomes more reactive and forms the sacrificial layer, so you transition from hydrodynamic lubrication to mixed mode lubrication, where you occasionally rupture the oil film in the high pressure zones of the engine.

Bruce,

I have this SAE paper in my files and have read it several times - the conclusions are pretty convincing.

 

[y_p_w]

quote:

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Originally posted by bruce381:
Also if oxidized ZDDP had any improvement over fresh there would be a product on the market and there are none I know of claming this.

Any suportive data published in known journals I would like to see maybe I can learn something new.
bruce

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Well - one well documented function of ZDDP is as an antioxidant. It would seem that "pre-oxidizing" the ZDDP would negate this function. I could also imagine that any pre-oxidized ZDDPs might plate out in the bottle, and it would be prefered that it be activated in the engine. Just a theory.

Here's some technical presentation, much of which goes over my head:

http://www.cse.clrc.ac.uk/events/Surfaces2004/Talks/Roberts.pdf

quote:

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ZDDP breaks down at high temperature

protective glass network film

possible structure

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[bruce381]

tooslick: I still find it hard to believe that the phospahte film wears off in cold start and heals at high temp but only if the ZDDP is oxidized. I would agree that changeing oil types and chemistry at each oil change could upset the film structure which is a good argument for NOT changes brands of oil.

I would love to read the SAE report if you would send a copy I will return favor with oil testing.

bruce fornesi
977 bransten road
san carlos, ca 94070

 

[y_p_w]

quote:

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Originally posted by Ironhorseman:
A base can be corrosive, just like an acid. As the oil's base additives are depleted, the PH is lowered. The closer to a PH of 7 you get, the less corrosive wear you see on metal.

This might not be the whole picture, but it's part of it.

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Possibly. However - I'd think the majority of the alkaline content in a motor oil is a weak base - i.e. a buffer. It wouldn't be like they'd mix a large amount of sodium hydroxide in there (although it might be possible that a tiny amount is used).

Also - I'm not sure if pH or pOH really applies to motor oil, at least not as we know it. From my HS chem, I seem to recall the terms are only meaningful in an "aqueous" solution. Absolutely pure water (even free of dissolved CO2) has an ionized H- concentration of 10^-7 molar and an ionized OH+ concentration of 10^-7 molar. This pH value for "neutral" would change depending on the solvent.

 

[JavaMan]

The older the violin the sweeter the music.

 

[GreeCguy]

Okay, so try this one on for size. If I drain the oil at 3,000 miles from my wife's car, (motor in good shape, clean and doesn't burn oil), and pour that in my old beater car that burns a quart every 700 miles, I am in fact doing the old beater car a service as the oil that I'm adding has been "broken in" so to speak.

 

[jorton]

quote:

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Originally posted by GreeCguy:
Okay, so try this one on for size. If I drain the oil at 3,000 miles from my wife's car, (motor in good shape, clean and doesn't burn oil), and pour that in my old beater car that burns a quart every 700 miles, I am in fact doing the old beater car a service as the oil that I'm adding has been "broken in" so to speak.

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And mix in some STP to replace the VI additive....

 

[Ramblin Fever]

So is this true for Dino oils as well?

Also, what do you do in the case of an engine that LIKES to have clean oil?

For instance, Isuzu's in particular like to be changed every 3K miles or their lifters start ticking louder.

 

[Ugly3]

quote:

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Originally posted by GreeCguy:
Okay, so try this one on for size. If I drain the oil at 3,000 miles from my wife's car, (motor in good shape, clean and doesn't burn oil), and pour that in my old beater car that burns a quart every 700 miles, I am in fact doing the old beater car a service as the oil that I'm adding has been "broken in" so to speak.

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Even if you are not giving the beater a benefit you are giving your wallet a definite benefit.

I did a 3 car rotation for years and years. New car ran the first 1500 miles on the oil, the next best car ran the second 1500 miles, and the beater burned all the oil coming out of the second best car. Never put new oil in the beater.

 

[Alex P.]

quote:

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Originally posted by Ugly3:
Even if you are not giving the beater a benefit you are giving your wallet a definite benefit.

I did a 3 car rotation for years and years. New car ran the first 1500 miles on the oil, the next best car ran the second 1500 miles, and the beater burned all the oil coming out of the second best car. Never put new oil in the beater.

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Ah, but if what they are saying is true, wouldn't breaking in the oil in the new car put extra wear on the engine?

 

[1sttruck]

hat was published about 6 years ago. Anyone seen any updates ? It was noted as almost being a new breakthrough, so an update seemed likely.

The paper seems to be confounded by the other statements that increased wear with new oil is due to disruption of the antiwear films on the engine internals, as the paper suggests that the reduced wear is due to a property of the used oil when added to an engine. Maybe the used oil is less disruptive to the antiwear films. It is contradicted by other studies that I've run across on diesel engines, where it was proposed to add abrasives to new oil in order to develop a standard used oil for testing. The Mobil 1 tests that were done using UOAs at short intervals suggested that Fe, and assumed wear, increased after 2k or 3k miles.

http://www.swri.edu/3pubs/IRD1999/03912699.htm

"Testing with partially stressed oil, which contained some wear debris, produced less wear than testing with clean oil. This finding was unexpected and initially confusing (further inquiry suggested that the result was not so surprising, as many oil chemistries require time and temperature to enhance their effectiveness). Although based on limited data, the finding could be significant, and verification should be pursued. If the finding is verified, the mechanisms should be determined, and ramifications with respect to oil change intervals, filter involvement, and additive packages should be considered. A similar finding for diesel engines could have even greater significance, since the topics of extended oil drain and, in some cases heavy exhaust gas recirculation are of major interest. Although the conditioning run altered the oil, it did not stress or render it unusable (as noted, there is indication that it was tribologically improved). As such, the impact of testing with significantly stressed oil was not measured and remains a future objective. "

 

[Gary Allan]

Not if he removes the oil before the 2-3k point at where the upramp occurs....or so one could reason by the UOA results. So far no one has done back to back 1500 miles UOAs to see if the even occurs anyway with new oil continuing where the old/new oil was removed.

So maybe we should all own a beater ..and treat it like a sacraficial lamb. A breeder reactor for "de-natured" oil.

 

[davefr]

Use the new oil for the beater car. Once it's broken in transfer it to the good car.

quote:

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Originally posted by GreeCguy:
Okay, so try this one on for size. If I drain the oil at 3,000 miles from my wife's car, (motor in good shape, clean and doesn't burn oil), and pour that in my old beater car that burns a quart every 700 miles, I am in fact doing the old beater car a service as the oil that I'm adding has been "broken in" so to speak.

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[Ramblin Fever]

quote:

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Originally posted by davefr:
Use the new oil for the beater car. Once it's broken in transfer it to the good car.

quote:

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.

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Yeah, but you don't know "what" all that beater car is transfering to the new car

 

[427Z06]

quote:

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Originally posted by y_p_w:
Nobody has really established that the wear rates are excessively high with new oil, only that it can be measured.

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Yep. Calculate how much metal is supposedly being removed during the first 1,000 miles of an OCI and I don't think we have anything to worry about. At least for the first 1,000 OCIs.