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Top Gear take on Engine Oil / OCI's
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A few things:
- as a piece of TV entertainment, it's not that bad. Sure, it is dumbed-down a bit but there's nothing really BAD about what they say
- this episode went out in October 2014, so a bit dated but not too old
- 10,000 miles is a common (and slightly old-fashioned) oil change interval in the UK.
- the presenter is an experienced race driver and instructor; I'd happily use her times as a yardstick
- kinematic viscosity at 100°C is one measure - the HTHS and MRV would give a better indication of drag to the engine; I'd wager these were higher than new
- I've driven that mile straight; maxed at 165 mph.
- as a piece of TV entertainment, it's not that bad. Sure, it is dumbed-down a bit but there's nothing really BAD about what they say
- this episode went out in October 2014, so a bit dated but not too old
- 10,000 miles is a common (and slightly old-fashioned) oil change interval in the UK.
- the presenter is an experienced race driver and instructor; I'd happily use her times as a yardstick
- kinematic viscosity at 100°C is one measure - the HTHS and MRV would give a better indication of drag to the engine; I'd wager these were higher than new
- I've driven that mile straight; maxed at 165 mph.
The consistency of the after change run (well inconsistency in times, the variablility in the post OCI runs is the same order of the claims of difference) makes at least the second series of runs questionable in terms of what's going on in addition to the oil change.
It's of the order of 3hp being claimed from an oil change...and average 3hp, obviously less at lower RPM, and more at the top end.
It's of the order of 3hp being claimed from an oil change...and average 3hp, obviously less at lower RPM, and more at the top end.
How much do you want to bet that in NASCAR, Indy car, NHRA etc.... All run new oil in each practice, qualifying, and each race?? I can just about say that it is all new oil before each race or run. And it is due in part to that helping those cars run faster than they would with old used oil.
Originally Posted By: bbhero
How much do you want to bet that in NASCAR, Indy car, NHRA etc.... All run new oil in each practice, qualifying, and each race?? I can just about say that it is all new oil before each race or run. And it is due in part to that helping those cars run faster than they would with old used oil.
Any evidence for that?
I'd think that, rather than a speed advantage, it might just be because they tear them down a lot, when the oil will naturally be changed, plus they run them at the screaming edge and put metal in their oil which might be damaging.
How much do you want to bet that in NASCAR, Indy car, NHRA etc.... All run new oil in each practice, qualifying, and each race?? I can just about say that it is all new oil before each race or run. And it is due in part to that helping those cars run faster than they would with old used oil.
Any evidence for that?
I'd think that, rather than a speed advantage, it might just be because they tear them down a lot, when the oil will naturally be changed, plus they run them at the screaming edge and put metal in their oil which might be damaging.
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Originally Posted By: Ducked
Originally Posted By: bbhero
How much do you want to bet that in NASCAR, Indy car, NHRA etc.... All run new oil in each practice, qualifying, and each race?? I can just about say that it is all new oil before each race or run. And it is due in part to that helping those cars run faster than they would with old used oil.
Any evidence for that?
I'd think that, rather than a speed advantage, it might just be because they tear them down a lot, when the oil will naturally be changed, plus they run them at the screaming edge and put metal in their oil which might be damaging.
Not only that, but it is my understanding that NASCAR will use a lighter oil for qualifying than for the main event where engine durability, dilution and the like become legitimate concerns.
Originally Posted By: bbhero
How much do you want to bet that in NASCAR, Indy car, NHRA etc.... All run new oil in each practice, qualifying, and each race?? I can just about say that it is all new oil before each race or run. And it is due in part to that helping those cars run faster than they would with old used oil.
Any evidence for that?
I'd think that, rather than a speed advantage, it might just be because they tear them down a lot, when the oil will naturally be changed, plus they run them at the screaming edge and put metal in their oil which might be damaging.
Not only that, but it is my understanding that NASCAR will use a lighter oil for qualifying than for the main event where engine durability, dilution and the like become legitimate concerns.
Here's some food for thought.
In API sequence VI test, there is actually a fuel economy measurement of new oil vs used oil, and the fuel economy always goes down on used oil. So there is a measurable difference between performance of new oil vs used oil - this is actually something that is discussed in the industry as new tests are developed and the argument of real-world correlation to the engine tests used to certify an oil.
Regarding thin oil making the car go slower it should actually be:
Oil diluted by fuel makes the car go slower. Which is true for a number of reasons - from heat transfer capacity, ineffective additives, inability to maintain MOFT etc etc.
A purpose built thin oil is not the same as one that is diluted down 15% by fuel.
In API sequence VI test, there is actually a fuel economy measurement of new oil vs used oil, and the fuel economy always goes down on used oil. So there is a measurable difference between performance of new oil vs used oil - this is actually something that is discussed in the industry as new tests are developed and the argument of real-world correlation to the engine tests used to certify an oil.
Regarding thin oil making the car go slower it should actually be:
Oil diluted by fuel makes the car go slower. Which is true for a number of reasons - from heat transfer capacity, ineffective additives, inability to maintain MOFT etc etc.
A purpose built thin oil is not the same as one that is diluted down 15% by fuel.
Originally Posted By: Solarent
Here's some food for thought.
In API sequence VI test, there is actually a fuel economy measurement of new oil vs used oil, and the fuel economy always goes down on used oil. So there is a measurable difference between performance of new oil vs used oil - this is actually something that is discussed in the industry as new tests are developed and the argument of real-world correlation to the engine tests used to certify an oil.
Relationship of that to viscosity is unclear without knowing more detail. It could be sheared, fuel diluted (if that isn't excluded by the test protocol) or oxidatively thickened.
Originally Posted By: Solarent
Regarding thin oil making the car go slower it should actually be:
Oil diluted by fuel makes the car go slower. Which is true for a number of reasons - from heat transfer capacity, ineffective additives, inability to maintain MOFT etc etc.
A purpose built thin oil is not the same as one that is diluted down 15% by fuel.
I had a Google and didn't find anything on this. A lot of what is readily available is for fuel dilution by biodiesel, which is quite likely to be different. Some papers looked at friction and/or wear, (mostly in bench tests) which does sometimes (though not always) go up with fuel dilution, so in those cases itd seem a fair bet that speed would go down.
Here's some food for thought.
In API sequence VI test, there is actually a fuel economy measurement of new oil vs used oil, and the fuel economy always goes down on used oil. So there is a measurable difference between performance of new oil vs used oil - this is actually something that is discussed in the industry as new tests are developed and the argument of real-world correlation to the engine tests used to certify an oil.
Relationship of that to viscosity is unclear without knowing more detail. It could be sheared, fuel diluted (if that isn't excluded by the test protocol) or oxidatively thickened.
Originally Posted By: Solarent
Regarding thin oil making the car go slower it should actually be:
Oil diluted by fuel makes the car go slower. Which is true for a number of reasons - from heat transfer capacity, ineffective additives, inability to maintain MOFT etc etc.
A purpose built thin oil is not the same as one that is diluted down 15% by fuel.
I had a Google and didn't find anything on this. A lot of what is readily available is for fuel dilution by biodiesel, which is quite likely to be different. Some papers looked at friction and/or wear, (mostly in bench tests) which does sometimes (though not always) go up with fuel dilution, so in those cases itd seem a fair bet that speed would go down.
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Originally Posted By: Ducked
Relationship of that to viscosity is unclear without knowing more detail. It could be sheared, fuel diluted (if that isn't excluded by the test protocol) or oxidatively thickened.
I wasn't making a comment about the viscosity, only that in a standardized test there is a clear difference between used oil and new oil. Most testing is performed on new oil only, and there is an argument to be made that some oils may protect well when new, but may lose effectiveness over the life of the drain. There are several additive chemistries that exhibit this behavior - MoDTC being one of them, LSPI inhibitors also seem to lose their effectiveness over the life of an oil drain.
Quote:
I had a Google and didn't find anything on this. A lot of what is readily available is for fuel dilution by biodiesel, which is quite likely to be different. Some papers looked at friction and/or wear, (mostly in bench tests) which does sometimes (though not always) go up with fuel dilution, so in those cases itd seem a fair bet that speed would go down.
I had another member ask me this question in a PM. I will post my response below.
Relationship of that to viscosity is unclear without knowing more detail. It could be sheared, fuel diluted (if that isn't excluded by the test protocol) or oxidatively thickened.
I wasn't making a comment about the viscosity, only that in a standardized test there is a clear difference between used oil and new oil. Most testing is performed on new oil only, and there is an argument to be made that some oils may protect well when new, but may lose effectiveness over the life of the drain. There are several additive chemistries that exhibit this behavior - MoDTC being one of them, LSPI inhibitors also seem to lose their effectiveness over the life of an oil drain.
Quote:
I had a Google and didn't find anything on this. A lot of what is readily available is for fuel dilution by biodiesel, which is quite likely to be different. Some papers looked at friction and/or wear, (mostly in bench tests) which does sometimes (though not always) go up with fuel dilution, so in those cases itd seem a fair bet that speed would go down.
I had another member ask me this question in a PM. I will post my response below.
From SAE 2015-01-0967:
"The unburned fuel entering the crankcase oil causes following impacts: (1) it dilutes concentrations of the oil additives such as wear, corrosion and oxidation inhibitors, dispersant, detergent, etc.; (2) it may react with some oil additives and reduce their functionalities; (3) it makes the oil become thinner and more volatile, causing degradation in engine lubrication due to dropping in oil viscosity, and deterioration in oil consumption due to more oil loading in the blowby as a result of increased volatility of the oil; (4) it shortens the oil change interval."
In addition to (2) and (3) above, its also clear that fuel can increase oxidation and deposit formation in engines as well, which puts more pressure on the additive package to disperse the varnish and soot particles, which in turn can use them up faster. TBN can also be drastically impacted as fuel mixing with oil can cause some acidic byproducts which are then neutralized by the higher base sulfonates and salicylates.
Most of the papers published on this topic in recent years either focus on dilution from TGDI (this is due to the increase flow of these engines in an effort to reduce LSPI) or the impact of biodiesel on fuel dilution and engine oil - which can result in polymerization and new deposit formation - part of the reason HDEO has a much higher concentration of dispersants compared to PCEO. An SAE search on Fuel Dilution will bring up some from as old as 1920 on the topic.
"The unburned fuel entering the crankcase oil causes following impacts: (1) it dilutes concentrations of the oil additives such as wear, corrosion and oxidation inhibitors, dispersant, detergent, etc.; (2) it may react with some oil additives and reduce their functionalities; (3) it makes the oil become thinner and more volatile, causing degradation in engine lubrication due to dropping in oil viscosity, and deterioration in oil consumption due to more oil loading in the blowby as a result of increased volatility of the oil; (4) it shortens the oil change interval."
In addition to (2) and (3) above, its also clear that fuel can increase oxidation and deposit formation in engines as well, which puts more pressure on the additive package to disperse the varnish and soot particles, which in turn can use them up faster. TBN can also be drastically impacted as fuel mixing with oil can cause some acidic byproducts which are then neutralized by the higher base sulfonates and salicylates.
Most of the papers published on this topic in recent years either focus on dilution from TGDI (this is due to the increase flow of these engines in an effort to reduce LSPI) or the impact of biodiesel on fuel dilution and engine oil - which can result in polymerization and new deposit formation - part of the reason HDEO has a much higher concentration of dispersants compared to PCEO. An SAE search on Fuel Dilution will bring up some from as old as 1920 on the topic.
Very nice. Thanks, Solarent.
Here's a question: How does fuel dilution ramp up with OCI length? I'd imagine it increases very quickly in the first several hundred/couple thousand miles, and then gradually starts to level off until it reaches some kind of equilibrium. Is that correct?
Here's a question: How does fuel dilution ramp up with OCI length? I'd imagine it increases very quickly in the first several hundred/couple thousand miles, and then gradually starts to level off until it reaches some kind of equilibrium. Is that correct?
Originally Posted By: Ducked
Nothing specific on speed there though.
You are right - My comment regarding to the oil diluted makes the car go slower was specific to the reference in the film, taking at face value the speed differential between the new oil and used oil.
Nothing specific on speed there though.
You are right - My comment regarding to the oil diluted makes the car go slower was specific to the reference in the film, taking at face value the speed differential between the new oil and used oil.
Originally Posted By: d00df00d
Very nice. Thanks, Solarent.
Here's a question: How does fuel dilution ramp up with OCI length? I'd imagine it increases very quickly in the first several hundred/couple thousand miles, and then gradually starts to level off until it reaches some kind of equilibrium. Is that correct?
There are several other SAE papers that examine the impact of driving pattern, speed, load, etc on fuel dilution. I honestly haven't spent enough time looking at the subject to make any kind of observation, but I'd guess that if anything the increased volatility of the oil makes it harder to measure the exact % of fuel in the oil as the oil ages (due to blowby).
Very nice. Thanks, Solarent.
Here's a question: How does fuel dilution ramp up with OCI length? I'd imagine it increases very quickly in the first several hundred/couple thousand miles, and then gradually starts to level off until it reaches some kind of equilibrium. Is that correct?
There are several other SAE papers that examine the impact of driving pattern, speed, load, etc on fuel dilution. I honestly haven't spent enough time looking at the subject to make any kind of observation, but I'd guess that if anything the increased volatility of the oil makes it harder to measure the exact % of fuel in the oil as the oil ages (due to blowby).
Originally Posted By: Solarent
Originally Posted By: Ducked
Nothing specific on speed there though.
You are right - My comment regarding to the oil diluted makes the car go slower was specific to the reference in the film, taking at face value the speed differential between the new oil and used oil.
OK, if you're saying its reasonably a possibility, fair enough. I thought you were stating it as a known fact, perhaps because you..er...did.
Originally Posted By: Ducked
Nothing specific on speed there though.
You are right - My comment regarding to the oil diluted makes the car go slower was specific to the reference in the film, taking at face value the speed differential between the new oil and used oil.
OK, if you're saying its reasonably a possibility, fair enough. I thought you were stating it as a known fact, perhaps because you..er...did.
Miles are far from dead over there.
We're an odd bunch. We use miles for distance and litres for volume, but still measure fuel economy in miles per gallon. It is illegal to sell goods in 'old' units, except for milk and beer, which can still be sold by the pint. We are the only country in Europe using miles, so our speedometers have to (by law) be capable of showing mph and km/h, even though most vehicles will never go anywhere where km/h is required. However the neighbouring European countries do not have to have mph available on their speedometers, even if they come here.
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