How much wear comes from engine start up? I know it is a vague question, but on an average car, are there any figures or tests on this?? I know in very cold weather the #s would be greater, but say for a moderate climate....
Engine start up wear question.......
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Most wear occurs in the first 15-20 minutes while the oil is to thick and not up to temperature. The easiest mode for an engine is staedy highway cruising. The worst thing you do to your engine is start it after it has sat and reached ambient temperature.
Most cylinder wear is from start up (up to 80% according to some sources); but would that be the same as saying most "engine" wear is due to start up? Engines still last 200-300k miles and your headgasket will likely blow before your piston rings. So don't worry.
Is a 5w-20 at say 20 degrees the same as a 30w at 95 degrees start up flow wise. A 5w-20 at 95 degrees is like water.
Hi,
This is a common question. Very few concise details really exist to prove the point but it is an enduring fact and has been stated as such for around 80 years or so! Most wear occure at cold startup all things being equal! It has always come from engine design Engineers and Oil Company Engineers
Some SAE Papers do allude to this too when the tests relate to wear rate tests/ viscosity comparisons and the like – in these cases lubricants are typically stabilised at around >80C prior to measurements being commenced – this ensures an even playing ground
Whilst some lubricant “issues” (additive behaviour etc) may be present and contribute to wear rates at cold start it is generally accepted that it is a factor of the various and disparate metallurgies being used in engines and their varying times to achieve their designed operating state of equilibrium
The retention (“plating”) requirement in lubricant quality ratings is known, as is the fact that boundary lubrication may play a role in certain engine families more than others at cold start up
This can be partially demonstrated by allowing an engine to run too cold (low crack point thermostat installed or none at all) against an engine operating in a similar application/situation with the best compromise thermostat installed. Wear will typically be more rapid in the engine that never reaches its correct operating temperature
Lubricants that are brought up quickly to a “balanced” temperature by using a coolant intercooler will most certainly perform better in wear rates and in maintaining lubricant condition. Some engines take up to 30 minutes or more to reach their operating equilibrium where the disparate metallurgies are operating harmoniously. In my Detroit Series 60 engines (38litres of oil/38 litres of coolant) this certainly takes a long time even though all of the fluid’s volume is not heated fully in most cases. Lubricants that flow better cold (eg 5W against 15W) and FF filters that are not in differential by-pass too long certainly help
I live in the Tropics and I have lived in Scandinavia. I was always intrigued as to why engines “living” in a hot climate do not last longer (in a direct comparison) than those with common sub-zero starts. Of course it is all to do with the cooling system/lubrication systems and metallurgical mix!
We do know however that engines that are maintained in their “ideal” operating temperature range are likely to outlast some of the components that may fail first - before the engine “wears” out !
So – IMHO the cold start wear rate is a factor of the engine’s design and the need to use a suitable quality lubricant of the correct viscosity! And there is a need to maintain the cooling and lubrication systems in the condition conceived by the engine’s designer and manufacturer. Excessive load and revs in a cold engine do not promote longevity either.
I hope this ramble adds something to the Thread without going in to too much detail
This is a common question. Very few concise details really exist to prove the point but it is an enduring fact and has been stated as such for around 80 years or so! Most wear occure at cold startup all things being equal! It has always come from engine design Engineers and Oil Company Engineers
Some SAE Papers do allude to this too when the tests relate to wear rate tests/ viscosity comparisons and the like – in these cases lubricants are typically stabilised at around >80C prior to measurements being commenced – this ensures an even playing ground
Whilst some lubricant “issues” (additive behaviour etc) may be present and contribute to wear rates at cold start it is generally accepted that it is a factor of the various and disparate metallurgies being used in engines and their varying times to achieve their designed operating state of equilibrium
The retention (“plating”) requirement in lubricant quality ratings is known, as is the fact that boundary lubrication may play a role in certain engine families more than others at cold start up
This can be partially demonstrated by allowing an engine to run too cold (low crack point thermostat installed or none at all) against an engine operating in a similar application/situation with the best compromise thermostat installed. Wear will typically be more rapid in the engine that never reaches its correct operating temperature
Lubricants that are brought up quickly to a “balanced” temperature by using a coolant intercooler will most certainly perform better in wear rates and in maintaining lubricant condition. Some engines take up to 30 minutes or more to reach their operating equilibrium where the disparate metallurgies are operating harmoniously. In my Detroit Series 60 engines (38litres of oil/38 litres of coolant) this certainly takes a long time even though all of the fluid’s volume is not heated fully in most cases. Lubricants that flow better cold (eg 5W against 15W) and FF filters that are not in differential by-pass too long certainly help
I live in the Tropics and I have lived in Scandinavia. I was always intrigued as to why engines “living” in a hot climate do not last longer (in a direct comparison) than those with common sub-zero starts. Of course it is all to do with the cooling system/lubrication systems and metallurgical mix!
We do know however that engines that are maintained in their “ideal” operating temperature range are likely to outlast some of the components that may fail first - before the engine “wears” out !
So – IMHO the cold start wear rate is a factor of the engine’s design and the need to use a suitable quality lubricant of the correct viscosity! And there is a need to maintain the cooling and lubrication systems in the condition conceived by the engine’s designer and manufacturer. Excessive load and revs in a cold engine do not promote longevity either.
I hope this ramble adds something to the Thread without going in to too much detail
Originally Posted By: Mamala Bay
Is a 5w-20 at say 20 degrees the same as a 30w at 95 degrees start up flow wise. A 5w-20 at 95 degrees is like water.
If the manual states a 5w-20 being in cold or ideal temp it is what I would use. Being serious a 5w-20 at 95 degree would be instant start up with no problems on start up wear. I wouldn't even worry about it.
Is a 5w-20 at say 20 degrees the same as a 30w at 95 degrees start up flow wise. A 5w-20 at 95 degrees is like water.
If the manual states a 5w-20 being in cold or ideal temp it is what I would use. Being serious a 5w-20 at 95 degree would be instant start up with no problems on start up wear. I wouldn't even worry about it.
Back in the early 80s I worked in a automotive engine shop for a couple years. A few things I noticed having to do with engine wear and start up. The most forward cylinder(s) closest to the radiator always had the most cylinder bore wear and bore taper by far, going by the readings I would get with a Sunnen bore gage.
Engines ran with no thermostat always had lots of cylinder wear. Engines ran with 160 degree thermostats were almost as bad. To this day I cringe when someone talks about running an engine with no thermostat. Engines that were used often for very short commutes back and forth to work to store with little highway use, always had lots of wear.
Right or wrong I came to the conclusion after awhile thermo dynamics play a huge roll on engine life expediency. As does changing your oil often enough for the conditions you drive.
Back than straight 30 weight 10w30 and 10w-40 and 20w-50 oils were commonly used.
Engines ran with no thermostat always had lots of cylinder wear. Engines ran with 160 degree thermostats were almost as bad. To this day I cringe when someone talks about running an engine with no thermostat. Engines that were used often for very short commutes back and forth to work to store with little highway use, always had lots of wear.
Right or wrong I came to the conclusion after awhile thermo dynamics play a huge roll on engine life expediency. As does changing your oil often enough for the conditions you drive.
Back than straight 30 weight 10w30 and 10w-40 and 20w-50 oils were commonly used.
Two issues here, and an addition that I've never pulled apart a dry engine.
When the oil is cold, it's viscosity is high...very high compared to running temperature, and parts are quite physically separated. When the oil is hot, the additives provide much of the wear protection (bearings are still predominantly hydrodynamic).
It's the bit in the middle, as the oil thins, and before the additives kick in that really wears things out.
As per Doug's post, if you pull apart a Holden 6 cyl, the wear ridge will be the greatest on #1 cylinder, as that's where the cold coolant from the radiator impinges. Once bought a V-8 where the previous owner had thrown out the thermostat (in a town that gets to -7C regularly), and the ridge was unbelievable at only 160,000km. Inlet valve guides were all oval (0.060" play transverse the head, exhaust guides not too bad)
When the oil is cold, it's viscosity is high...very high compared to running temperature, and parts are quite physically separated. When the oil is hot, the additives provide much of the wear protection (bearings are still predominantly hydrodynamic).
It's the bit in the middle, as the oil thins, and before the additives kick in that really wears things out.
As per Doug's post, if you pull apart a Holden 6 cyl, the wear ridge will be the greatest on #1 cylinder, as that's where the cold coolant from the radiator impinges. Once bought a V-8 where the previous owner had thrown out the thermostat (in a town that gets to -7C regularly), and the ridge was unbelievable at only 160,000km. Inlet valve guides were all oval (0.060" play transverse the head, exhaust guides not too bad)
And yet the 7 brg Holden most often had failure of No5 piston,more so on the dreaded 179.
Its fascinating to think that a person who drives 10-20 miles each way to work is going to wear out his engine because it never sees full operating temperature for very long. I've driven that way my whole life and every car I owned was always disposed of for something other than needing an engine or engine work. Either I got tired of them, or they fell apart.
I recall doing valve jobs and cam and lifter replacements on cars when I was in high school, the the cylinders still had hone marks and no ridges. Only 1 car I remember that needed rings and was badly worn was a Rambler American flat head 6, but that car was neglected.
I think that whole start up wear thing might just be a little over rated. Reading about it would almost lead a person to believe that starting up a car and driving it 20 minutes is like running it w/o oil for 20 minutes, and we all know what happens when you run a car w/o oil.
JMO,
Frank D
I recall doing valve jobs and cam and lifter replacements on cars when I was in high school, the the cylinders still had hone marks and no ridges. Only 1 car I remember that needed rings and was badly worn was a Rambler American flat head 6, but that car was neglected.
I think that whole start up wear thing might just be a little over rated. Reading about it would almost lead a person to believe that starting up a car and driving it 20 minutes is like running it w/o oil for 20 minutes, and we all know what happens when you run a car w/o oil.
JMO,
Frank D
Originally Posted By: Silk
And yet the 7 brg Holden most often had failure of No5 piston,more so on the dreaded 179.
2 and 5 (same phase), but personally had 2 number 5s fall apart as I pulled them apart, and my brother had a #2 exit stage right.
And yet the 7 brg Holden most often had failure of No5 piston,more so on the dreaded 179.
2 and 5 (same phase), but personally had 2 number 5s fall apart as I pulled them apart, and my brother had a #2 exit stage right.
Originally Posted By: rg200amp
I use redline 5w20, so i guess i am coverd all around, anyway at start up the oil is not at 20wt or 30wt, its at the smaller number. i use 5w20, so the 5 will flow very quickily.
What do you think your oil thickens to a 20wt as it warms up?
I use redline 5w20, so i guess i am coverd all around, anyway at start up the oil is not at 20wt or 30wt, its at the smaller number. i use 5w20, so the 5 will flow very quickily.
What do you think your oil thickens to a 20wt as it warms up?
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I remember when I had my 1st 3000GT,when I would start it on a very cold day (when the temp was near/or below freezing) after it either sat for awhile or the very first start up of the day it always sounded like a dry start for a few seconds when I was using a 10w30 wt oil. That was one scary noise! When I changed it out to a slightly thicker oil,10w40,the dry start noise NEVER happened again.
That made me think of what GN said and what I`ve read on a few other car forums (3si and tt.net) that the thicker oils coat the engine internals better after shutdown than thinner oils and remain in the valvetrain areas better as well. I`m sure there are a ton of variables as well (different cars,different engine designs,etc.). My 3000GT`s owners manual (1996 model) spec`d/recommended a thicker oil (10w40-20w50) for racing,extended high speed driving,and warm climates and didnt even mention anything thinner than 10w30.
That made me think of what GN said and what I`ve read on a few other car forums (3si and tt.net) that the thicker oils coat the engine internals better after shutdown than thinner oils and remain in the valvetrain areas better as well. I`m sure there are a ton of variables as well (different cars,different engine designs,etc.). My 3000GT`s owners manual (1996 model) spec`d/recommended a thicker oil (10w40-20w50) for racing,extended high speed driving,and warm climates and didnt even mention anything thinner than 10w30.
Good past thread: https://bobistheoilguy.com/forums/posts/1103628/
Originally Posted By: rg200amp
I use redline 5w20, so i guess i am coverd all around, anyway at start up the oil is not at 20wt or 30wt, its at the smaller number. i use 5w20, so the 5 will flow very quickily.
This statement reflects one of the greatest misconceptions about the SAE grading scheme. The W part of the rating is NOT a viscosity range like the "hot" part of the rating is. It simply reflects whether the oil has passed certain tests that generally assess the oil's performance in cold situations. You could say it has some relation to viscosity, but it's not a vis rating at all. It is quite possible, for example to have a 0w rated oil that's actually thicker at a given "cold" temp than certain 5w oils are. GC, for example is one oil that's thicker than many 5w oils, but because of its ability to remain liquid and pumpable at very low temps, it qualifies for the 0w rating, while many 5w oils, especially dinos are thinner in vis, but solidify and become unpumpable at higher temps, and therefore don't qualify for the 0w rating. Clear as mud?
I use redline 5w20, so i guess i am coverd all around, anyway at start up the oil is not at 20wt or 30wt, its at the smaller number. i use 5w20, so the 5 will flow very quickily.
This statement reflects one of the greatest misconceptions about the SAE grading scheme. The W part of the rating is NOT a viscosity range like the "hot" part of the rating is. It simply reflects whether the oil has passed certain tests that generally assess the oil's performance in cold situations. You could say it has some relation to viscosity, but it's not a vis rating at all. It is quite possible, for example to have a 0w rated oil that's actually thicker at a given "cold" temp than certain 5w oils are. GC, for example is one oil that's thicker than many 5w oils, but because of its ability to remain liquid and pumpable at very low temps, it qualifies for the 0w rating, while many 5w oils, especially dinos are thinner in vis, but solidify and become unpumpable at higher temps, and therefore don't qualify for the 0w rating. Clear as mud?
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