Oil Teperature v Engine wear graph?

[expat]

I once saw such a thing, the numbers generated by research done by Continental (I think). It basically showed very high wear rates at 0c dropping very rapidly upto bout 70c then trailing off to negligible amount at about 90c.
Anyone have a link please.
or something similar.

 

[Gary Allan]

If you read the works of Dr. Haas ..where he quotes the research of the now famous Schneider (spl?). The curve flattens out with the oil temp. That was in a non-exchanged engine, so we didn't know if it was oil temp or what also occurred with oil temp being the co-product/byproduct. The closer you got to normalized oil temps ..the lower the wear.

 

[expat]

I'll read Dr Haas's writings again, I'd really like to see/get a copy of a graph for a talk I have to give.

 

[Gary Allan]

You'll need to ante up for the SAE paper by the esteemed Schnider (spl?) I believe it's titled "cylinder and ring wear" or cylinder/ring wear" or "cylinder-ring wear". I think it was $12-$15+/-

 

[mechtech2]

Those temperatures cited in the original post seem to be accurate for coolant temperature and wear .

Oil temp? It's kinda related, but I can't see why there would be more wear at mid temps than high oil temps.

 

[steve20]

from my recollection the wear rate was parabolic



Steve

 

[Gary Allan]

Originally Posted By: mechtech2
Those temperatures cited in the original post seem to be accurate for coolant temperature and wear .

Oil temp? It's kinda related, but I can't see why there would be more wear at mid temps than high oil temps.



The paper basically found that the start up wear curve normalized over a 20 minute period. Coolant was normalized long before 20 minutes.

This wasn't an oil endurance/wear/temp test. It was to measure startup (full warm up) wear. The wear curve tracked the oil temp. Normalized oil temp ..no wear.

This led to 3 basic schools of thought.

Dr. Haas - viscosity - it too tracks the normalized oil temp. As oils warm - they converge in likeness of visc.

Additive activation - those who suggest a required temp for the chemical reactions of AW elements. It too would track oil temp.

My first thought of co-occurring events (this was cylinder:ring wear being measured) was piston expansion since it too would reach thermal equilibrium over that same curve.

One subset school of thought, one that I tend to reject for significance, is corrosive wear due to acid formations during the immediate warm up stage. While I'm not rejecting the notion of the process, I tend to give it little significance in the measured wear curve.

Unfortunately, there was no follow up or augmentation to the study to isolate various elements. One would warm the oil or coolant to isolate a couple. Then both. This would have left part expansion as the single element. Warming oil would have eliminated additive activation and left cool cylinders for the acid theory (a isolated dry sump could be employed) ..and one would merely compare the wear of a 40 weight to the wear curve of a 20 weight to determine if visc reduced the curve in amplitude.

I imagine that it's a combination of all of them.

 

[il_signore97]

Gary,

I think you've hit the nail on the head regarding the three schools of thought. I would also agree that it is a combination of those 3 elements that gives us our total "start-up wear".

I do remember reading a paper on start-up wear (I can't remember what I did with it though), and it listed chemical wear as high on the scale of significance with respect to all of the start-up wear mechanisms. I know that you prefer to reject it, but according to the paper, it may have more involvement than we think. Basically, the paper ranked mechanical wear (of any cause) to be lower on the scale of significance than chemical wear on a cold start-up.

I couldn't tell you either way, but it makes sense to me. Also, given that pretty much all start-up wear is isolated to cylinder walls / piston rings, it does make sense from that point of view.

Interesting stuff indeed...

 

[mechanicx]

Originally Posted By: mechtech2
Those temperatures cited in the original post seem to be accurate for coolant temperature and wear .

Oil temp? It's kinda related, but I can't see why there would be more wear at mid temps than high oil temps.


That is my understanding that there is a relationship between coolant temperature and wear, mostly cylinder wall and ring wear, but also some other splash lubricated parts. Oil temperature is related to coolant temperature anyway. If your oil is hot/cold your coolant is hot/cold.

 

[mechanicx]

Originally Posted By: il_signore97
Gary,

I think you've hit the nail on the head regarding the three schools of thought. I would also agree that it is a combination of those 3 elements that gives us our total "start-up wear".

I do remember reading a paper on start-up wear (I can't remember what I did with it though), and it listed chemical wear as high on the scale of significance with respect to all of the start-up wear mechanisms. I know that you prefer to reject it, but according to the paper, it may have more involvement than we think. Basically, the paper ranked mechanical wear (of any cause) to be lower on the scale of significance than chemical wear on a cold start-up.

I couldn't tell you either way, but it makes sense to me. Also, given that pretty much all start-up wear is isolated to cylinder walls / piston rings, it does make sense from that point of view.

Interesting stuff indeed...

I also think acid wear in cold start can be/is a factor. A big reason you are seeing higher cylinder wear is a lot to do with cold cylinder/coolant temperatures. Also there is fuel enrichment at play too.

 

[Gary Allan]

While I don't reject the acid/corrosive formations in cold starting, I have difficulty attributing the length of the curve to having that be the primary contributor to the measured result. Fuel enrichment, out of the 20 minute event, should be rather short. The cylinder walls may be cool/cold ..but they don't stay that way too long. The areas subject to the combustion process will always be at a very high temperature. I would expect the condensing blow-by to have more impact (as we currently recognize) on the oil in the crankcase.

Now don't get me wrong, you can and will find situations where an engine never gets warmed ..fuel enrichment is always the norm ..and the cooling system, let alone the oil ..will not get up to temp. There you will have all of the 4 horsemen of doom present and might still have a hard time tallying who got the most kills since all will be at their most severe and will all contribute their worst to the whole scenario.

 

[Eddie]

Mercedes Benz did a cylinder bore wear vs coolant temp or oil temp years ago and it was parabolic as Steve20 stated

 

[Gary Allan]

There's plenty of studies showing that running TOO COOL a coolant temp produced excessive wear.

This is totally different than the wear curve of the engine during the warm up process.

It assumes a defect ..assures it ..and sees the result.

It's like saying if you run your sump dry ..it will seize ..just not as severe.

There are ideal and practical operational coolant temps. I can't see how any study where they are deficient can offer validity here.

 

[expat]

Gary, I think you and I are seeing the same things, We see studies that show the Engine wear after a cold start, and a decrease in wear as the engine warms up.
Now an engine may reach full operational 'Coolant' temp after 8 minutes (thanks to a thermostat) but oil temp may take 20 minutes to reach optimal.
What I would 'like' to see is a Kink in the graph when the coolant has reached operational level, yet engine wear still decreases (at a slower rate) while the engine oil is still warming.
Or, show the two graphs, one monitoring coolant temp the other Oil temp, but also add a time scale!
Heck, Then do it all again with the addition of Upper cyl lube in the gas.

 

[JohnBrowning]

Another similar paper by Lubrizol and Toyota found that coolant temp and sulfur content of the fuel both tracked with ring wear. Some of the research in that paper Toyota used latter on to design their new XXZZ-FE line of engines. They did a lot of flow testing to determine just how much oil flow each part was getting versus what it actually needed. THey also used radio active isotopes so they could accurately track the wear FE to make sure they where just looking at FE from the rings and not the rest of the engine.

 

[JohnBrowning]

In fact the ideal sit. in racing would be to have really cold coolant and nicely warmed oil before the start of the race and to keep it stable. The enhanced cooling if it could be done would drasticly allow one to produce more power safely while the prewarmed oil would allow for more HP and better functioning from the start of the race all the way through tot he end.

 

[mechanicx]

Originally Posted By: expat
Gary, I think you and I are seeing the same things, We see studies that show the Engine wear after a cold start, and a decrease in wear as the engine warms up.
Now an engine may reach full operational 'Coolant' temp after 8 minutes (thanks to a thermostat) but oil temp may take 20 minutes to reach optimal.
What I would 'like' to see is a Kink in the graph when the coolant has reached operational level, yet engine wear still decreases (at a slower rate) while the engine oil is still warming.
Or, show the two graphs, one monitoring coolant temp the other Oil temp, but also add a time scale!
Heck, Then do it all again with the addition of Upper cyl lube in the gas.

It would seem to me that the oil would always be hotter and warm up faster than the coolant. the oil is the first level of coolant and has the most close contact to friction and heating parts. Why would the coolant heat up faster than the oil? Sure oil might be slightly less efficient heat conductor than water, but water also has a higher thermal mass and takes longer to rise in temperature. Add to that there's usually more coolant than oil and the coolant has less intimate contact with engine parts.

If cylinder wall wear is higher when a cooler thermostat is used, how is that any different than saying cooler coolant temperatures during start up also cause more wear? Hot running cngine clearances can't be met until the average coolant temperature and engine temperature are met. Coolant temps and oil temps are related. If your coolant is cooler or hotter, your oil oil is cooler or hotter too.

 

[expat]

[/quote]

It would seem to me that the oil would always be hotter and warm up faster than the coolant. the oil is the first level of coolant and has the most close contact to friction and heating parts. Why would the coolant heat up faster than the oil? Sure oil might be slightly less efficient heat conductor than water, but water also has a higher thermal mass and takes longer to rise in temperature. Add to that there's usually more coolant than oil and the coolant has less intimate contact with engine parts.

[/quote]

Oil is slower to warm than the coolant, partially because a coolant thermostat is used, and also because the coolant plays a bigger role in cooling the really hot parts of the engine (the combustion chamber, and particularly around the exhaust ports)
The hottest part the engine oil cools is the underside of the piston. Not too much of the total heat is actually generated by friction.
Seldom, on the average road car will the oil get hotter than the coolant.

 

[mechanicx]

Originally Posted By: mechanicx


It would seem to me that the oil would always be hotter and warm up faster than the coolant. the oil is the first level of coolant and has the most close contact to friction and heating parts. Why would the coolant heat up faster than the oil? Sure oil might be slightly less efficient heat conductor than water, but water also has a higher thermal mass and takes longer to rise in temperature. Add to that there's usually more coolant than oil and the coolant has less intimate contact with engine parts.



Quote:
Oil is slower to warm than the coolant, partially because a coolant thermostat is used, and also because the coolant plays a bigger role in cooling the really hot parts of the engine (the combustion chamber, and particularly around the exhaust ports)
The hottest part the engine oil cools is the underside of the piston. Not too much heat is actually generated by friction.


Well I'm not so sure about that. I don't see what the thermostat matters really it's closed but the water is still being circulate through the engine and heater core. The only thing you mention is the exhaust heating up the coolant faster, but plenty of oil runs over the top of the exhaust valve and right over the cylinder head. The back of pistons and rings is a quickly heating hot spot too.

 

[expat]

[/quote]
Well I'm not so sure about that.[/quote]

Ever fitted an oil temperature gauge?