greatest contribution to wear reduction
- Thread starter bonnie john
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Sorry, you're wrong.
Oh you might find exceptions, like in a race engine where the engine is running at it's design limits for it's entire life. But for the general vehicle population, run under normal use on public streets, cold startup wear is the dominating variable when it comes to engine life. And this isn't strictly thick/thin oil thing either.
I think the percentage contribution of cold startup wear to total wear depends entirely on the length of the duty cycle....
It would be more accurate to say that cold start wear contributes perhaps 50%-75% of total wear, depending on how many miles (and under what conditions), the engine is running after startup.
Needless to say, the 50%-75% is just a "WAG"....
TS
It would be more accurate to say that cold start wear contributes perhaps 50%-75% of total wear, depending on how many miles (and under what conditions), the engine is running after startup.
Needless to say, the 50%-75% is just a "WAG"....
TS
Sure TS, you can play with the numbers, pointing out exceptions for people who have long commutes. But that's always the case when you're dealing with such generalities. You debate the exceptions ad infinitum.
Better material and surface treatment,closer tolerances with less tollerance stacking, more precise ignition and fuel control, paper air and oil filters have all helped. Generaly when you look at UOA it is very safe to assume that those companies that consistently produce low wear metals in their engines are doing a better job at all of the above items. Some companies use much higher grade materials and finner surface finish's. Some companies engine plants are very clean and while others are very dirty.
What a lot of people may not see at times when looking at UOA is the difference in these factors from one company to another. You can have the best design in the world but if you use the cheapest alloys that will do and the bare minimum of heat treat and surface finish's then you end up with a sub standard end product.
You mentioned Toyota in your post. If you compare the aluminum used in their intake manifolds and blocks and compare it to GM's you will notice that the GM alloy is a lesser alloy and is very porus as compared Toyota's. You find that most of GM's rods are either cast or powder metal while Toyota's are forged. The same thing goes for the crankshaft and pistons. Most of GM's are cast while most of Toyota's newer engines are forged. This is not meant to be a rip on GM post so I am going to end it here.
Most engines being belt by OEM's today are all of suffcient design in terms of mechanical wear. The difference is in the material used and how well finished the parts are. Most of what we see in UOA is an indication of material quality rather then design.
What a lot of people may not see at times when looking at UOA is the difference in these factors from one company to another. You can have the best design in the world but if you use the cheapest alloys that will do and the bare minimum of heat treat and surface finish's then you end up with a sub standard end product.
You mentioned Toyota in your post. If you compare the aluminum used in their intake manifolds and blocks and compare it to GM's you will notice that the GM alloy is a lesser alloy and is very porus as compared Toyota's. You find that most of GM's rods are either cast or powder metal while Toyota's are forged. The same thing goes for the crankshaft and pistons. Most of GM's are cast while most of Toyota's newer engines are forged. This is not meant to be a rip on GM post so I am going to end it here.
Most engines being belt by OEM's today are all of suffcient design in terms of mechanical wear. The difference is in the material used and how well finished the parts are. Most of what we see in UOA is an indication of material quality rather then design.
The cold start wear discussion reminds me the infamous consumer report taxi study when it was determined that engine wear was minimal and did not vary with the OCI or type or brand of oils.
Of course, as those taxi engines always run.
So much for the CR expertise.
Of course, as those taxi engines always run.
So much for the CR expertise.
One more point: the wear in modern engines is so low, that you can decrease the oil viscosity and even decrease the AW additives in oils and still observe no decrease of service life (at least in light duty cars and trucks).
Some excerpts from one study I've read:
A cold start can cause between 200-1000 miles or wear (we normalized by the wear rate with fresh oil at highway speeds). Some of this is due to build up of unburnt hydrocarbons which aggregate while the oil is cold and are not boiled off. Some is due to acidic attack of the engine metal due to oxidation of the oil and hydrobromic acids which aren't boiled off until the engine is warmed above 140F...
...If you don't idle much, and warm fairly quickly, the start could be as little as 100 miles of wear, but if the initial temperature was low, you idled to warm, you take a very short trip, and your oil is average, wear can be 1000 miles/startup...
...if you subtract off the metal dissolution rates from the non-load mechanisms you still get 100-500 miles of wear from insufficient lube at start up...
...Driving a car with a warm engine, with clean, good oil on a flat highway at constant highway speeds causes extremely light wear. If you could do this without stopping your engine you could expect 2,000,000 miles out of your engine...
A cold start can cause between 200-1000 miles or wear (we normalized by the wear rate with fresh oil at highway speeds). Some of this is due to build up of unburnt hydrocarbons which aggregate while the oil is cold and are not boiled off. Some is due to acidic attack of the engine metal due to oxidation of the oil and hydrobromic acids which aren't boiled off until the engine is warmed above 140F...
...If you don't idle much, and warm fairly quickly, the start could be as little as 100 miles of wear, but if the initial temperature was low, you idled to warm, you take a very short trip, and your oil is average, wear can be 1000 miles/startup...
...if you subtract off the metal dissolution rates from the non-load mechanisms you still get 100-500 miles of wear from insufficient lube at start up...
...Driving a car with a warm engine, with clean, good oil on a flat highway at constant highway speeds causes extremely light wear. If you could do this without stopping your engine you could expect 2,000,000 miles out of your engine...
I remember several years ago Cummins did a test that had a engine running on a dyno constantly only shut down for oil changes and when they measured the wear compared to engines with the same amount of running time that was shut down and allowed to cool they determined that on the average truck with 600,000 miles on it 80 percent of the wear was from startup. Since then their has been advances made in engine design fuel/ oil/ and machining so those numbers probably no longer are true The new diesels are turbocharged and they have a much lower static compression ratio than the old naturally aspirated engines that means they don't have the pressure on the rod bearings at startup before they get oil pressure.
[ August 27, 2006, 08:31 PM: Message edited by: Black Bart ]
[ August 27, 2006, 08:31 PM: Message edited by: Black Bart ]
I would believe, just from common sense, that cold starts would contribute the significant amount of wear. Precise numbers, I could only guess at. But consider that when an engines starts it has to produce oil pressure to the main bearing, rod bearings, valve train and so on. It is the pressure that creates the "float" that keeps engine bearing surfaces from eroding. Ever put your finger and thumb underneath a small stream of fast flowing water? You can rub them back and forth and they feel so slick. That is because they are not touching each other (thumb and finger) You are feeling water. Same with oil and bearing parts. Once the engine is started and oil pressure is built, the rod bearings no longer make contact with the rods, but just float on oil. Part of the fact that synthetic oil contributes to lower heat is the uniformity of oil molecules and their ability for the "float" condition to be enhanced. When you first start an engine, there is pressure on the main and rod bearings. After that there is next to nil. So i have to agree with previous posts about cold starts contributing to wear.
2nd: Filtration reduces the size of particles that "polish" the mating parts. You can polish parts only for so long and even if the wear is in millionth, it's still wear. Better filtration and I believe those that use bypass filters, AND change the bypass filter elements religiously, will have some of the lowest wearing engines around. Case in point? http://www.gulfcoastfilters.com/1,000,000 MILES.htm
This Peterbuilt truck had over 1,000,000 miles on it and still has most of the original engine parts and running toward 1.5 million miles. 2 things are noted. It is a truck. They run long hauls, and so the engine is more often than not constantly running. Even when they park for a few hours truckers have the tendency to just leave the truck run ESPECIALLY in cold weather, like winters in Cheyenne WY. They did this with Shell Rotella 15-40 oil. But, again as mentioned earlier, cold starts are eliminated a lot in truck engines, and since they were removing the contaminants most related to wear, they have documented proof of longer wear due to less containments. There was another Peterbuilt with similar engine, but did not have the same bypass filters setup and it did last a long time but it's wear pattern was more "normal" for trucks of that mileage and age.
Good food for thought in all these discussions!
2nd: Filtration reduces the size of particles that "polish" the mating parts. You can polish parts only for so long and even if the wear is in millionth, it's still wear. Better filtration and I believe those that use bypass filters, AND change the bypass filter elements religiously, will have some of the lowest wearing engines around. Case in point? http://www.gulfcoastfilters.com/1,000,000 MILES.htm
This Peterbuilt truck had over 1,000,000 miles on it and still has most of the original engine parts and running toward 1.5 million miles. 2 things are noted. It is a truck. They run long hauls, and so the engine is more often than not constantly running. Even when they park for a few hours truckers have the tendency to just leave the truck run ESPECIALLY in cold weather, like winters in Cheyenne WY. They did this with Shell Rotella 15-40 oil. But, again as mentioned earlier, cold starts are eliminated a lot in truck engines, and since they were removing the contaminants most related to wear, they have documented proof of longer wear due to less containments. There was another Peterbuilt with similar engine, but did not have the same bypass filters setup and it did last a long time but it's wear pattern was more "normal" for trucks of that mileage and age.
Good food for thought in all these discussions!
Startup wear makes a lot of common sense. If you assume the ideal viscosity of oil is 10 (just to pick a round number), then there is obviously a problem when the viscosity of a straight 50 oil at 40 deg. C (a warm temperature) is 240, or 24 times that ideal. Even a 5w50 synthetic is 105 at 40 C, or 10 times ideal. Imagine what is going on by the time you hit moderately cool temperatures like 10C, which is still well above freezing.
Even if you are in the molasses camp, a 0w40 is still only 15 or so at running temp. Why on earth would you want 5 to 15 times that viscosity on each startup? I would suggest you done, and the price is startup wear.
Even if you are in the molasses camp, a 0w40 is still only 15 or so at running temp. Why on earth would you want 5 to 15 times that viscosity on each startup? I would suggest you done, and the price is startup wear.
My car showed the same amount of lead wear, in 5600 miles of winter driving with lots of cold starts, as with 7500 miles of summer highway driving with very few cold starts. But the iron and aluminium wear was much worse over winter. It looks like pressure buildup to the bearings isn't an issue for me. It's probably fuel washout in the cylinder bores that's the big problem. If I could warm up the engine on propane, it might last forever.
How does one solve the fuel washing problem -- 10w30, so it leaves a thicker film when cold, or 0w30, so it gets splashed around sooner?
How does one solve the fuel washing problem -- 10w30, so it leaves a thicker film when cold, or 0w30, so it gets splashed around sooner?
I can tell you one thing not to do. These people are probably dying off now, but it was quite fashionable at one time to accelerate your engine when shutting it down. i.e. rev it up and then turn the key off. With fuel injection I suspect most engines are smart enough to stop the gas immediately, but with carburators you sucked a bunch of fuel in as the engine coasted down. Yes it started better that way in cold weather, but you also washed all the oil off the cylinder walls!
On a more practical basis, I would think anything to make the engine start quicker would help - keep it tuned up, use thin oil, and keep it plugged in if necessary.
What is the class of aftermarket device called that pressurizes the oil before you start the engine?
They are designed to prevent "dry starts".
They are designed to prevent "dry starts".
It has been postulated that diesel engines last much longer than gas engines [in general] because their fuel has a natural lubricity, and helps with piston - ring - bore wear.
Adding some Lucas UCL or marvel Mystery oil to the gas should help this area.
Adding some Lucas UCL or marvel Mystery oil to the gas should help this area.
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I think this perceverating on "startup" is totally misaligned with what wear we see in engines. That is, the wear has little to do with lubrication. It has mostly to do with ill fitting parts that have higher wear until they are warmed up. No oil is going to change that pattern of wear. We don't see much bearing wear in UOA from short run/short trip engines ..but according to the impressions that you seem to have ..a short trip car should be heavily laden with Pb in the UOA. In most that I've seen ..it's way down on the list compared to others.
Every reciprocating engine in existance eventually has oval cylinders. That's the wear that you cannot avoid and most of it occurs during startup (warm up). No oil is going to alter that wear much one way or another.
Every reciprocating engine in existance eventually has oval cylinders. That's the wear that you cannot avoid and most of it occurs during startup (warm up). No oil is going to alter that wear much one way or another.
Even Maxlife 10w-40?
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Every member is allowed to have one silver bullet ..one holy grail that assures them that their engine will live forever.
It's the law of BITOG
It's the law of BITOG
Thus, per Gary Allan's argument, we don't need an engine pre-luber.
What we need, ladies and gentlemen, is a heater under our hoods that keeps the engine at a constant 210 degrees!
I sure couldn't afford the energy, but maybe if I was the kind of guy who towed his Ferrari out of the garage when he had to get his Maybach out from behind it so it didn't have startup wear, I would spring for that device and associated power bills.
Might not be too ridiculous, depending, to have a device like that which KNEW I was going to start the car between 0830 and 0835 every morning. Hmmmm.
Oooh! And if I did that, I could run SAE 30 year round!
What we need, ladies and gentlemen, is a heater under our hoods that keeps the engine at a constant 210 degrees!
I sure couldn't afford the energy, but maybe if I was the kind of guy who towed his Ferrari out of the garage when he had to get his Maybach out from behind it so it didn't have startup wear, I would spring for that device and associated power bills.
Might not be too ridiculous, depending, to have a device like that which KNEW I was going to start the car between 0830 and 0835 every morning. Hmmmm.
Oooh! And if I did that, I could run SAE 30 year round!
I still remember when you had to remove a ridge before removing pistons from the block. When common cylinder taper was between 5 and 10 thousands of an inch. Replacement rings were designed with forgiveness for such tolarences. An engine block with as little as 50,000 miles on it needed to be rebored when rebuilding it, and minimum oversize was 20 thousands of an inch.
What has changed? Certainly the materials are better. The oils are much better. But still to me the biggest improvement is that the oil isn't getting near the load of fuel dilution from the long outdated fuel control system, carbs. If we still had such heavy fuel dilution, even with all the rest of the improvements would not being doing much good. Compared with 30 or 40 years ago, we don't even know what sludge is. Sludge that was largly agrivated from fuel dilution.
What has changed? Certainly the materials are better. The oils are much better. But still to me the biggest improvement is that the oil isn't getting near the load of fuel dilution from the long outdated fuel control system, carbs. If we still had such heavy fuel dilution, even with all the rest of the improvements would not being doing much good. Compared with 30 or 40 years ago, we don't even know what sludge is. Sludge that was largly agrivated from fuel dilution.
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