Amsoil SS vs Z-ROD

[garageman402]

OK, so the Signature Series has the best wear protection, so why would I need higher ZDDP for flat tappet engines? Also isn't the timing chain another source of shearing, so would higher ZDDP levels extend the chain life as well? AFAIK, the reason ZDDP was reduced is to keep phosphorus out of cat converters, so if I have a non-cat vehicle, would I be better off using Z-ROD instead of SS?
Z-ROD is only available in 10w-30, 10w-40, & 20w-50, but (I forget his name) the guy from FL with the Lamborghinis says you want the lowest possible cold viscosity so it gets to the specified working viscosity faster on cold starts. The Z-ROD 10w-30 has a viscosity of 74.9 cSt @ 40C (104F), & the manufacturer's specified oil (30) has a vis of about 10cSt at 100C (212F). The engine likes to have 10cSt oil circulating through it & on a hot Florida day it is 74.9cSt. Therefore, a 0w-30 (57.1 cSt @ 40C) would protect better than a 5w-30 or 10w-30 on cold starts. I am running SS 0w-30 for that reason, also it's the same price as 5w-30. Would the Z-ROD have a better film, so start-up wear would be reduced?

 

[twX]

The engine likes to have 10cSt oil circulating through it & on a hot Florida day it is 74.9cSt. Therefore, a 0w-30 (57.1 cSt @ 40C) would protect better than a 5w-30 or 10w-30 on cold starts.

Any grade of oil will protect an engine just fine when the oil is at 40 C. It's when the oil is extremely cold at >3,000 cP, or extremely hot at
A 0W-30 will effectively be thinner at operating temperature than a 10W-30 and will provide less protection, even though they might have similar viscosity at 100 C. The reason has to do with how much the viscosity drops when the oil experiences high shear rates. The Amsoil Z-ROD 10W-30 is better than the SS in this regard, with an HTHS of 3.6 cP vs 3.11 cP. The HTHS of Amsoil SS 0W-30 is similar to the SS 10W-30, at 3.07 cP, but at higher shear rates it will thin out much more than the 10W-30. The 10W-30 oils also have much lower NOACK.

 

[OVERKILL]

Depending on how wild the cam is, will determine whether you can get away with the API-neutered levels of phosphorous or not. If it's just a stock bumpstick, you'll probably be fine.

 

[ka9mnx]

 

[kschachn]

OK, so the Signature Series has the best wear protection, so why would I need higher ZDDP for flat tappet engines? Also isn't the timing chain another source of shearing, so would higher ZDDP levels extend the chain life as well? AFAIK, the reason ZDDP was reduced is to keep phosphorus out of cat converters, so if I have a non-cat vehicle, would I be better off using Z-ROD instead of SS?
Z-ROD is only available in 10w-30, 10w-40, & 20w-50, but (I forget his name) the guy from FL with the Lamborghinis says you want the lowest possible cold viscosity so it gets to the specified working viscosity faster on cold starts. The Z-ROD 10w-30 has a viscosity of 74.9 cSt @ 40C (104F), & the manufacturer's specified oil (30) has a vis of about 10cSt at 100C (212F). The engine likes to have 10cSt oil circulating through it & on a hot Florida day it is 74.9cSt. Therefore, a 0w-30 (57.1 cSt @ 40C) would protect better than a 5w-30 or 10w-30 on cold starts. I am running SS 0w-30 for that reason, also it's the same price as 5w-30. Would the Z-ROD have a better film, so start-up wear would be reduced?

Where are you seeing wear tests that show it to be the best?

And you don’t understand “cold start” wear protection.

 

[garageman402]

Where are you seeing wear tests that show it to be the best?

Here's the wear test from Amsoil, ya it's advertising, but is it legit?

https://www.amsoil.com/p/signature-series-0w-30-synthetic-motor-oil-azo/

Here's the Z-ROD

https://amsoilcontent.com/ams/lit/databulletins/g2883.pdf

And you don’t understand “cold start” wear protection.

The faster you can get oil circulating, the faster it can start protecting, although a thin oil may drain away leaving a truly dry start. What am I missing?

 

[facility1]

just a curious question on flow rates,does, the anti-wear package moly,boron,titanium, zinc etc play a part in startup wear reduction along with base stock capabilities in a PCMO of a given compairable viscosity ?

 

[garageman402]

just a curious question on flow rates,does, the anti-wear package moly,boron,titanium, zinc etc play a part in startup wear reduction along with base stock capabilities in a PCMO of a given compairable viscosity ?

I think that it would in some places, such as bearings where a good amount of oil is trapped, but places that get squirt or splash maybe not so much. Under the piston is very hot, & when shut off the extremely hot, thin oil runs away, how long until that area (rings, wrist pins) gets lube on a cold start? How much moly or zinc or phosphorous is left to protect it until fresh lube arrives? Would a 10w-30 hold up better in the under piston area than a 0w-30 or even a 5w-30?

One thing I have noticed using the 0w-30 is after prolonged parking (1-2 months), even after 10 seconds of "flood clear" cranking, the lifters are noisy. In fact one engine barely ran because the lifters weren't pumped up yet. Took about 20-30 seconds for it to start running smooth. That is making me re-think the 0w theory of quick cold flow.

 

[350Rocket]

I think that it would in some places, such as bearings where a good amount of oil is trapped, but places that get squirt or splash maybe not so much. Under the piston is very hot, & when shut off the extremely hot, thin oil runs away, how long until that area (rings, wrist pins) gets lube on a cold start? How much moly or zinc or phosphorous is left to protect it until fresh lube arrives? Would a 10w-30 hold up better in the under piston area than a 0w-30 or even a 5w-30?

One thing I have noticed using the 0w-30 is after prolonged parking (1-2 months), even after 10 seconds of "flood clear" cranking, the lifters are noisy. In fact one engine barely ran because the lifters weren't pumped up yet. Took about 20-30 seconds for it to start running smooth. That is making me re-think the 0w theory of quick cold flow.

I have not experienced this with 0w40 m1 in my 84 Oldsmobile parked from November to April and I just crank until it fires, usually about 4-5 seconds.

 

[OVERKILL]

The faster you can get oil circulating, the faster it can start protecting, although a thin oil may drain away leaving a truly dry start. What am I missing?

Oil pumps on most engines are positive displacement, so if the oil can get up the pick-up, how quickly the pump moves it out doesn't change. The only caveat here is if the pump is on the relief, some of that oil is being bypassed back to the feed side to keep oil pressure under control.

So, if you've got 20W-50 in your standard clearanced SBC that you decided to put an HV/HP pump into, and the pump has a 55psi relief and you are hitting 75psi once it fires, you are on the bypass. That means that:
The pump picked up the oil, fully enveloped the engine, the back-pressure that was produced once this occurred exceeded the relief pressure on the pump, so the pump started to bypass some of the oil back to the feed side of the pump to keep the pressure down, however, the bypass is too small to handle the required volume to get it down to the relief pressure, so total system pressure remains elevated.

At this point, you are just thrashing the oil with the pump, sending some of it through the bypass because you've chosen an oil that's too thick for the application and probably have way too much pump on top of that.

 

[garageman402]

Oil pumps on most engines are positive displacement, so if the oil can get up the pick-up, how quickly the pump moves it out doesn't change. The only caveat here is if the pump is on the relief, some of that oil is being bypassed back to the feed side to keep oil pressure under control.

So, if you've got 20W-50 in your standard clearanced SBC that you decided to put an HV/HP pump into, and the pump has a 55psi relief and you are hitting 75psi once it fires, you are on the bypass. That means that:
The pump picked up the oil, fully enveloped the engine, the back-pressure that was produced once this occurred exceeded the relief pressure on the pump, so the pump started to bypass some of the oil back to the feed side of the pump to keep the pressure down, however, the bypass is too small to handle the required volume to get it down to the relief pressure, so total system pressure remains elevated.

At this point, you are just thrashing the oil with the pump, sending some of it through the bypass because you've chosen an oil that's too thick for the application and probably have way too much pump on top of that.

I think you're backing up my statement about thinner oils working better?

I disagree that the engine is "fully enveloped" in oil when first started. The larger galleys are full, but the back pressure had built up before the thick oil can get through the smaller passages, such as splash/jet oiling of piston bottoms, valve train, etc. It will be "thrashing the oil with the pump" until it warms up enough to thin out (which may be by sheer oil friction), depriving the engine of much needed lubrication on start-up.

An engine designed for 30 oil is designed for 10cSt viscosity. In a perfect world, oil would be at 10cSt at all temps, but, alas, it's not. The 0w-30 I have mentioned has a 40C vis of 57.1cSt, so it doesn't have far to go to get to the desired 10cSt. So if it's 104F outside, the 0w-30 is at 57.1cSt.

Depending on how wild the cam is, will determine whether you can get away with the API-neutered levels of phosphorous or not. If it's just a stock bumpstick, you'll probably be fine.

The BBC has an "RV" cam with power range of 1500-4400 RPM, so not too radical. My thought is the Higher ZDDP would be beneficial even if it's not so stressed. Timing chains also stress oil, so I'm wondering if there'd be a benefit there, as well as leaving a protective coating to protect during start-up before the cold thick oil can reach it. Even with a roller cam, would there be benefits to extra ZDDP levels? I'm not too keen on a 10w-30, but that's the thinnest they offer. Both of these vehicles are in Texas now in a non-emission county, so cat protection is a non-issue. Yes, I know I should be more concerned with high temp operation, but as I stated, even at 104F, 0w-30 is still 57.1 cSt.

Adding too much ZDDP has been found to have the opposite effect on wear. I read of a test where aftermarket ZDDP additive was added to cheap oil, & it actually showed an improvement. But when it was added to a high quality oil it actually showed a decrease in wear protection. I would presume (hope) Amsoil formulates the Z-ROD correctly, not just boosting levels as a selling point. They do state that it meets SL specs, so I would assume it's formulated correctly. (Edit)

 

[garageman402]

Any grade of oil will protect an engine just fine when the oil is at 40 C. It's when the oil is extremely cold at >3,000 cP, or extremely hot at
A 0W-30 will effectively be thinner at operating temperature than a 10W-30 and will provide less protection, even though they might have similar viscosity at 100 C. The reason has to do with how much the viscosity drops when the oil experiences high shear rates. The Amsoil Z-ROD 10W-30 is better than the SS in this regard, with an HTHS of 3.6 cP vs 3.11 cP. The HTHS of Amsoil SS 0W-30 is similar to the SS 10W-30, at 3.07 cP, but at higher shear rates it will thin out much more than the 10W-30. The 10W-30 oils also have much lower NOACK.

The 0w-30 does have the highest NOACK of all. I was attracted to the SS 0w-30 due to the similarities with the SS 5w-30 & SS 10w-30, with the added benefit of lower 40C cSt. So would the higher AW property of the Z-ROD make up for the slower flow at cold start in terms of wear (74.9cSt compared to 57.1cSt)?

 

[garageman402]

I have not experienced this with 0w40 m1 in my 84 Oldsmobile parked from November to April and I just crank until it fires, usually about 4-5 seconds.

Maybe the higher HTHS vis played a part? The one that took 20-30 sec was put away very hot. When I first turned it on the A/C was cranked up to max (I was not the one who parked it).

 

[OVERKILL]

I think you're backing up my statement about thinner oils working better?

No, I'm explaining a necessary caveat that needs to be understood when talking about "flow" at start-up.

I disagree that the engine is "fully enveloped" in oil when first started.

I didn't say that. Re-read the statement. You won't engage the relief unless the system pressure hits what's required, and that won't happen until the engine is full enveloped, if it happens at all.

The larger galleys are full, but the back pressure had built up before the thick oil can get through the smaller passages, such as splash/jet oiling of piston bottoms, valve train, etc. It will be "thrashing the oil with the pump" until it warms up enough to thin out (which may be by sheer oil friction), depriving the engine of much needed lubrication on start-up.

You are missing it.

The pump will only be thrashing the oil by sending it back through the relief, if the system pressure is high enough to do so. This happens only after the engine is fully enveloped, if it happens at all. That's why I provided an "extreme case" example, which you don't appear to have properly processed.

An engine designed for 30 oil is designed for 10cSt viscosity. In a perfect world, oil would be at 10cSt at all temps, but, alas, it's not. The 0w-30 I have mentioned has a 40C vis of 57.1cSt, so it doesn't have far to go to get to the desired 10cSt. So if it's 104F outside, the 0w-30 is at 57.1cSt.

No engine is designed around a single grade of oil. They are designed to be tolerant of a wide range of oils, with the thinnest safe grade typically recommended, for fuel economy. The important part is to not go below the safe range for that piece of equipment. As the years have progressed, and more effort has been put into chasing fuel economy, that tolerance for thinner and thinner oils has been pushed further and further, and changes to engine design, including special coatings, and wider bearings, have been necessitated to facilitate that.

My 6.4L and my 5.7L have the same bearing clearances, one specs 0W-20, the other specs 0W-40. The difference? The 392 rev's higher, is expected to be tracked, and makes 74HP/L, vs 69HP/L for the 5.7. Ford famously spec'd 5W-20 and 5W-50 for the SAME ENGINE, depending on whether the car was sold with the "track pack" option or not. The track pack got an oil cooler and a highly modified or completed omitted oil temperature neutering system (this was never clarified) which would significantly reduce the power output on the 5W-20 spec cars once oil temp got sufficiently high.

While I appreciate efforts to simplify things by trying to put them in these tidy little boxes, it's never that easy unfortunately.

The BBC has an "RV" cam with power range of 1500-4400 RPM, so not too radical. My thought is the Higher ZDDP would be beneficial even if it's not so stressed.

What are the spec's on it though? Does it have aggressive ramp rates and high lift or is it just generally pretty mild overall?

Timing chains also stress oil,

That is primarily brought up when we are discussing SOHC and DOHC engines with 6 miles of timing chains, not a pushrod engine.

so I'm wondering if there'd be a benefit there, as well as leaving a protective coating to protect during start-up before the cold thick oil can reach it. Even with a roller cam, would there be benefits to extra ZDDP levels?

All oils are going to leave a protective coating. I generally lean toward the full-SAPS phosphorous levels of 900-1100ppm. There's no mandated compromise in this area, so these levels are chosen because they are optimal, not because they are mandated.

I'm not too keen on a 10w-30, but that's the thinnest they offer. Both of these vehicles are in Texas now in a non-emission county, so cat protection is a non-issue. Yes, I know I should be more concerned with high temp operation, but as I stated, even at 104F, 0w-30 is still 57.1 cSt.

That visc figure doesn't matter unless you are on the relief, as I noted. What pump do you have in the engine? What's the relief setting? Are you hitting that pressure?

Adding too much ZDDP has been found to have the opposite effect on wear. I read of a test where aftermarket ZDDP additive was added to cheap oil, & it actually showed an improvement. But when it was added to a high quality oil it actually showed a decrease in wear protection. I would presume (hope) Amsoil formulates the Z-ROD correctly, not just boosting levels as a selling point.

That's a problem with adding anything to a fully formulated oil, the odds of making it better are always approaching zero.

Without having any real data on the build details, I'm hard pressed to recommend anything. I'd probably be inclined toward a 5W-40 personally, because it's old American iron. I typically run 0W-40 in my Windsors, but I am running 5W-40 D1 in the 351W in our boat, but it spins higher than your BBC does (though not often).

 

[Rat407]

Also, ZRod is made for those vehicles that sit and not started for months at a time. So the additive package is built with that in mind to help with moisture and acids that build up from infrequent use if that makes sense.

 

[OVERKILL]

Also, ZRod is made for those vehicles that sit and not started for months at a time. So the additive package is built with that in mind to help with moisture and acids that build up from infrequent use if that makes sense.

Yep, it's specifically engineered with extra effort placed on corrosion inhibition for garage queens that go out to car shows a few times during the summer. That was considered as part of the oil's development. A thoughtful inclusion by AMSOIL, but may not be a necessary feature depending on your usage case.

 

[twX]

The faster you can get oil circulating, the faster it can start protecting, although a thin oil may drain away leaving a truly dry start. What am I missing?

You're not wrong about the oil pressure building up faster with thinner oil on a cold start (at least when the oil is thick enough for the oil pump to be bypassing). The question is, how much does this actually matter in terms of overall engine wear when the oil is not extremely cold?

In the California climate, any difference in startup wear between grades is probably going to be insignificant in terms of total engine wear. Engines still last hundreds of thousands of miles here in Canada, despite routinely starting with very thick oil in the winter.

Here's a chart from a study that measured oil pressure at the cam bearings (the last part of the system to become pressurized) with 10W-40 oil. With the oil at 20 C (around 300 cST), there is positive pressure at the cams within 2 seconds of when the engine starts cranking, and probably within a fraction of a second of the engine achieving idle speed.

Compare this to the test at -30 C, where the engine cranks for 15 seconds before firing up, takes another 17 seconds of idling to see any oil pressure at the cams, and then another 50 seconds of idling to see full oil pressure. Oil grade really matters in these extreme cold conditions, but there are diminishing returns as the oil gets thinner.

 

[kschachn]

You're not wrong about the oil pressure building up faster with thinner oil on a cold start (at least when the oil is thick enough for the oil pump to be bypassing). The question is, how much does this actually matter in terms of overall engine wear when the oil is not extremely cold?

In the California climate, any difference in startup wear between grades is probably going to be insignificant in terms of total engine wear. Engines still last hundreds of thousands of miles here in Canada, despite routinely starting with very thick oil in the winter.

Here's a chart from a study that measured oil pressure at the cam bearings (the last part of the system to become pressurized) with 10W-40 oil. With the oil at 20 C (around 300 cST), there is positive pressure at the cams within 2 seconds of when the engine starts cranking, and probably within a fraction of a second of the engine achieving idle speed.

View attachment 184065
Compare this to the test at -30 C, where the engine cranks for 15 seconds before firing up, takes another 17 seconds of idling to see any oil pressure at the cams, and then another 50 seconds of idling to see full oil pressure. Oil grade really matters in these extreme cold conditions, but there are diminishing returns as the oil gets thinner.

On the other hand you have a high and persistent MOFT which mitigates the need for replenishment, unless you rev the engine excessively high. On a reasonable start “cold start wear” is not the issue that it is often imagined to be.

 

[OVERKILL]

You're not wrong about the oil pressure building up faster with thinner oil on a cold start (at least when the oil is thick enough for the oil pump to be bypassing). The question is, how much does this actually matter in terms of overall engine wear when the oil is not extremely cold?

In the California climate, any difference in startup wear between grades is probably going to be insignificant in terms of total engine wear. Engines still last hundreds of thousands of miles here in Canada, despite routinely starting with very thick oil in the winter.

Here's a chart from a study that measured oil pressure at the cam bearings (the last part of the system to become pressurized) with 10W-40 oil. With the oil at 20 C (around 300 cST), there is positive pressure at the cams within 2 seconds of when the engine starts cranking, and probably within a fraction of a second of the engine achieving idle speed.

View attachment 184065
Compare this to the test at -30 C, where the engine cranks for 15 seconds before firing up, takes another 17 seconds of idling to see any oil pressure at the cams, and then another 50 seconds of idling to see full oil pressure. Oil grade really matters in these extreme cold conditions, but there are diminishing returns as the oil gets thinner.

One caveat I would note with respect to this chart is that a 10W-40 is not within its CCS Winter range at -30C. It's Cold Cranking rating is only until -25C, it's the wrong oil choice at those temperatures.

But, this is where the age of that study presents some unique issues.

The current CCS test (ASTM D5293) was not in use at the time of the paper. The method in use at the time was ASTM D2602, which was withdrawn in 1993 and replaced by D5293.

I know the paper is from '89, but does it give a date for when the testing was performed? Because J300 also transitioned from D3829 for MRV to D4684 at the end of the 80's.

Here's why I bring this up. This is current J300:

So, 10W-40 wouldn't be suitable below -25C due to cranking restrictions, but should still pump down to -30C, so the test is appropriate, right?

Well.... No.

Because here's J300 in 1989 (there's no cranking column if we go back to 1987...):

It wasn't until 1999 that the modern revisions were made. So, in 1989, it wasn't appropriate to use a 10W-40 below -20C, and it wasn't expected to pump below -25C. So, depending on the base oils and PPD's used, that oil could have been INSANELY thick, and not representative of a modern 10W-40, even ignoring that the application isn't appropriate anyways.

And, ultimately, this test is a very good demonstration as to why the MRV test exists. Will it pump? If the answer is no, you have problems. The oil needed to get sufficient heat in it to start moving up the pick-up and through the engine, so there was a good period there where no oil was flowing because the pump couldn't draw it in. A positive displacement pump can't move any oil if it isn't receiving any through the pick-up, lol.

 

[twX]

One caveat I would note with respect to this chart is that a 10W-40 is not within its CCS Winter range at -30C. It's Cold Cranking rating is only until -25C, it's the wrong oil choice at those temperatures.

I realize that the test at -30 C is extreme for this oil, but I chose to discuss it since it's the only one of the four tests that the authors provided a cranking time for. It's unclear when the engine actually fired up during the -20 and -25 C tests, which makes them more difficult to interpret.

It wasn't until 1999 that the modern revisions were made. So, in 1989, it wasn't appropriate to use a 10W-40 below -20C, and it wasn't expected to pump below -25C. So, depending on the base oils and PPD's used, that oil could have been INSANELY thick, and not representative of a modern 10W-40, even ignoring that the application isn't appropriate anyways.

There's a table showing the CCS measurements, but I'm not sure what difference the older test methods would have on these figures. The top two rows are 15W oils. The thickest 10W oils seem to be just above the limits for a modern 10W. The oil used in the Figure 4 test is referred to as a "typical" 10W-40, so I assumed it may be the one that's 4,000 cP at -25 C, but it's unclear. MRV was not provided, but the test oil was said to a "borderline pumping temperature of -29 C, which leads me to believe that it wasn't especially thick compared to a modern 10W.

There's some more detailed data on one of the cranking tests with a 10W at -25 C that shows the pre-filter oil pressure rising quickly, indicating that the oil is pumpable. It does take just over 10 seconds, but the engine speed was slowly ramped up to normal cranking speed over the first 10 seconds.