Anybody Use Straight WT Oil - Page 3 - PeachParts Mercedes-Benz Forum

mannys9130 · #31 02-28-2016, 04:04 PM

The 40 is less viscous when hot. 20w-50 is less viscous than straight 40 until warmed up where it doesn't thin as much as 40 grade. So yes, the 20w-50 will flow better than the 40 grade when cold and lead to less oil starvation.

The "band aid" comments aren't derogetory, they're simply reality. I explained in the PM how easy it is to change lifters, so I just don't know why you want to do what you're doing.

As long as you're happy...

leathermang · #32 02-28-2016, 05:44 PM

Quote:

Originally Posted by mannys9130

..... less oil starvation. .....

Where do you get the idea there is ANY oil starvation going on ?

mannys9130 · #33 02-28-2016, 10:27 PM

Whenever any engine is shut down, oil drains down and thickens as it cools. At startup, the engine runs for a short time when there is no pressurized lubrication, and metal on metal contact occurs. This is when engines experience the most wear. When the engine is driven when it's cold, the parts may demand a flow rate that is not possible due to the viscosity of the oil. In that case, the oil film is weak and metal contact occurs again causing wear. Once the oil is warmed up all the way, no starvation occurs. At the moment of starting and during the time when the engine is heating up are where the most wear occurs and when oil viscosity is the most "wrong" for the engine. There is no difference between 5w-40, 15w-40, and 40 grade oil when they are all at operating temp. The 5w thickens the least when cooling from its proper viscosity. The 15w thickens a lot and the straight 40 grade thickens considerably. That's the reason why it causes starvation. Even a straight 5 grade oil is too thick when cold, but it's too thin at operating temp. So you mix up an oil that flows like a 5 grade when cold, but doesn't thin more than a straight 40 grade does. It's ideal, and the cold start does less damage to the engine since oil flows much more quickly, and since cold start wear is greatly reduced the overall wear of the engine is reduced over its lifetime.

babymog · #34 02-29-2016, 09:56 AM

I don't think that you even came close to answering leathermang's question, nor anyone else's and gave no new information.

Also, there certainly is a difference between 5W-40 a 15W-40, and an SAE-40 at operating temperatures, this is because of how multi-viscosity oils are produced and due to the different basestocks necessary for a 5W vs a 15W vs a straight SAE-40. You need to do more research to understand how engine oils are formulated, which will eventually lead to a molecular level, bonding, polymer chains and shear sensitivity (to prevent viscosity breakdown), additive packages to increase the tenacity of the oil and to provide lubrication/protection for startup, base numbers, the ability to prevent acidity and electro-galvanic corrosion, solid lubricant additives, moisture suspension, flocculants to improve filtration efficiency, etc., etc. Your recommendation of oil is IMO based on very little real knowledge or understanding of how lubricants are designed, manufactured, specified, ... and no knowledge of actual test results of these oils in a Mercedes-Benz engine.

Unless you have actual data showing that one engine had more wear or a failure than another, in identical conditions, with two different oils (called "facts"), you are only speculating and your posts are all opinion. We all realize that different oils have different properties, but you also continue to ignore the fact that previous contributors to this thread have posted that the SAE-30 and SAE-40 are recommended for use in this engine, which is a pretty good indicator that it is suitable. This is likely based on extensive research and testing, not speculation and opinion.

If you have new facts, testing, and data that specifically proves why the Mercedes-Benz recommended lubricants for this engine are not suitable for this engine feel free to post. Until then you are IMO just like the Lucas Oil display with the two plastic gears in oil to show that Lucas is obviously better for an automotive engine because it clings to two slow-moving plastic gears better.

leathermang · #35 02-29-2016, 10:47 AM

Quote:

Originally Posted by mannys9130

Whenever any engine is shut down, oil drains down and thickens as it cools. At startup, the engine runs for a short time when there is no pressurized lubrication, and metal on metal contact occurs. This is when engines experience the most wear. When the engine is driven when it's cold, the parts may demand a flow rate that is not possible due to the viscosity of the oil. In that case, the oil film is weak and metal contact occurs again causing wear. Once the oil is warmed up all the way, no starvation occurs. At the moment of starting and during the time when the engine is heating up are where the most wear occurs and when oil viscosity is the most "wrong" for the engine. There is no difference between 5w-40, 15w-40, and 40 grade oil when they are all at operating temp. The 5w thickens the least when cooling from its proper viscosity. The 15w thickens a lot and the straight 40 grade thickens considerably. That's the reason why it causes starvation. Even a straight 5 grade oil is too thick when cold, but it's too thin at operating temp. So you mix up an oil that flows like a 5 grade when cold, but doesn't thin more than a straight 40 grade does. It's ideal, and the cold start does less damage to the engine since oil flows much more quickly, and since cold start wear is greatly reduced the overall wear of the engine is reduced over its lifetime.

The oil drains down... but not all of it... there is typically a film of oil remaining on working surfaces to help until the pressurized oil gets back to the part.
The increased wear upon startup includes all the time until the inside of the engine comes to working temperature.. stuff does not fit at the designed specs until then... that is why good pistons are not round... but ovoid ... when they expand due to heat they are more restricted in one direction by the piston pin structure.... but not 90 degrees to that... so they expand to fit the bore properly after warming up. So to blame the initial lack of full pressure ( minus a pre oiler ) is not fair to the overall picture.
Our oil pumps are way over designed.... On a system with an overly robust oil pump using a pressure relief valve this notion of ' parts requiring more flow rate than available' is dramatic visualization rather than day to day reality. Same with ' flows much more quickly'. The ' much' I do not think you have evidence for.... and we might be talking a quarter of a second... I don't know... but these engines last SO LONG I think some of the wording in your descriptions using the word' starvation ' are misleading.
Particularly since we are discussing three or four oils which are listed IN THE SAME temperature box in the FSM for this engine...

mannys9130 · #36 02-29-2016, 07:20 PM

Quote:

Originally Posted by babymog

I don't think that you even came close to answering leathermang's question, nor anyone else's and gave no new information.

Also, there certainly is a difference between 5W-40 a 15W-40, and an SAE-40 at operating temperatures, this is because of how multi-viscosity oils are produced and due to the different basestocks necessary for a 5W vs a 15W vs a straight SAE-40. You need to do more research to understand how engine oils are formulated, which will eventually lead to a molecular level, bonding, polymer chains and shear sensitivity (to prevent viscosity breakdown), additive packages to increase the tenacity of the oil and to provide lubrication/protection for startup, base numbers, the ability to prevent acidity and electro-galvanic corrosion, solid lubricant additives, moisture suspension, flocculants to improve filtration efficiency, etc., etc. Your recommendation of oil is IMO based on very little real knowledge or understanding of how lubricants are designed, manufactured, specified, ... and no knowledge of actual test results of these oils in a Mercedes-Benz engine.

Unless you have actual data showing that one engine had more wear or a failure than another, in identical conditions, with two different oils (called "facts"), you are only speculating and your posts are all opinion. We all realize that different oils have different properties, but you also continue to ignore the fact that previous contributors to this thread have posted that the SAE-30 and SAE-40 are recommended for use in this engine, which is a pretty good indicator that it is suitable. This is likely based on extensive research and testing, not speculation and opinion.

If you have new facts, testing, and data that specifically proves why the Mercedes-Benz recommended lubricants for this engine are not suitable for this engine feel free to post. Until then you are IMO just like the Lucas Oil display with the two plastic gears in oil to show that Lucas is obviously better for an automotive engine because it clings to two slow-moving plastic gears better.

Since you think I'm a troll, I'm perplexed by your continuing to respond. I'm glad you add that your thoughts are your opinion. My research is extensive, and simply because I list it in laymen's isn't a reason to assume that it isn't so. My recommendation is based on a culmination of all things.

I have answered Greg's question very thoroughly and I won't be continuing to go back and forth on this. My information and points have been presented. You know why I assert what I do, and so does Greg. I encourage both of you to do further reading on the topic.

MTUpower · #37 02-29-2016, 07:33 PM

Quote:

Originally Posted by mannys9130

No... Straight grades have been obsolete for decades.

5W-40 diesel oil is the best. I run it year round in Tucson. My lifters used to tap and tick all the time, so I replaced them. Now they're always silent and it's wonderful. Replace yours and run the 5w-40 synthetic.

Some diesel engine should not be run for any length of time on non straight weights. Detroit Diesel 92 series for example are required to be run on straight 40 CF-2 rated oils in normal ambient operating temps.

Blanket statements are very hard to defend my friend.

babymog · #38 02-29-2016, 08:59 PM

So your response is rhetoric again Manny? Not even an attempt to find a single real fact or test result to support yur rants. Classic, and completely predictable. My point as well as several others' who have called you out in this thread is simply to expose that you have no expertise and that your advice is nothing more than opinion followed by stubbornness. Thank you for makinv it easy.