You can have the same effect without a tune or plugin hardware by driving in M5. That's what I do.
M1 AFE 0W-30 7,418 miles 2014 GMC Sierra 5.3
- Thread starter gonefishing
- Start date
- Status
dnewton3
Staff member
I did some investigation and here's what I found:
Code:
GM Vortec Gen IV engines
oil mi veh mi Al Cr Fe Cu Pb
4.8L
avg 5705 101216 2.9 .9 15.4 26.4 7.4
stdev 3240 50075 .9 .6 7.8 24.1 11.3
5.3L
avg 5721 90919 4.0 1.0 22.1 30.8 3.1
stdev 2926 53484 2.0 .6 16.0 29.8 3.7
6.0L
avg 5588 94469 3.8 .8 21.4 33.5 5.2
stdev 2522 59898 3.3 .6 12.7 28.3 6.5
6.2L
avg 5915 79385 5.6 1.4 31.1 34.6 8.5
stdev 3421 53866 2.7 .8 22.8 32.7 13.3
I am left with the conclusion that using the DoD/AFM (displacement on demand - active fuel management; or whatever GM wants to call it) seems to affect the Fe wear. I say this because the 4.8L engine is the only one that does not use the fuel savings technology, AFAIK. The three other engines (5.3L, 6.0L, 6.2L) use this technology. The DoD system selectively shuts off certain cylinders by shutting down the fuel injection, and also manipulating the lifters so that they don't raise the rockers to activate the intake and exhaust valves. (See the post I had one page back that has a copy/paste of the details).
Whereas one can argue that a single UOA or series from one vehicle may skew this concept, there are nearly 4400 UOAs (four thousand four hundred) in my database now for the Vortec engine series. That's a LOT of data. And I used the ones that I can confirm by vehicle year to assure they are Gen IV engines; probably close to 500 UOAs in this study alone. All manner of variation is already accounted for. Don't complain or object because you think someone's bed load or driving style will alter the data, because I use MACRO data analysis and therefore all the variation of real world inputs are taken into account.
Looking closely at the data, the Al, Cr, Cu and Pb are all reasonably consistent across all four engine displacements. However, note that Fe is significantly higher with the three larger engines. The 5.3L and 6.0L are nearly identical in terms of all metals, in fact. The Fe in the 5.3/6.0 has a mean shift great enough that it's aligned with a stdev contrasted to the 4.8L. The 6.2L engine is two stdev outside of the 4.8L in Fe. But the other wear metals (Al, Cr, Cu, Pb) are all within a fairly tight group across all four engines. The Fe in the 4.8L engine averages around 2.7ppm/1k miles. The three larger engines with Dod/AFM are all much higher. Hence the fuel management system definitely increases the Fe wear. Folks, while we cannot conclude that the DoD/AFM is the sole contributor to higher Fe wear, we can say with confidence it is probably the main contributor to the rise in Fe wear!
Now, again, I want to emphasize that this does not mean the GM fuel economy feature is bad, or that the GM engines have a flaw. DO NOT PUT YOUR INTERPRETATION INTO MY DATA; DON'T USE YOUR WORDS TO FILL MY MOUTH. What I'm stating here is that there is clear evidence to conclude that the DoD/AFM technology is the most likely contributor to escalated Fe readings. That escalation in wear rates is not indicative of any mode of mechanical failure; it only serves to understand the phenomenon so that UOA data can be better understood.
Code:
GM Vortec Gen IV engines
oil mi veh mi Al Cr Fe Cu Pb
4.8L
avg 5705 101216 2.9 .9 15.4 26.4 7.4
stdev 3240 50075 .9 .6 7.8 24.1 11.3
5.3L
avg 5721 90919 4.0 1.0 22.1 30.8 3.1
stdev 2926 53484 2.0 .6 16.0 29.8 3.7
6.0L
avg 5588 94469 3.8 .8 21.4 33.5 5.2
stdev 2522 59898 3.3 .6 12.7 28.3 6.5
6.2L
avg 5915 79385 5.6 1.4 31.1 34.6 8.5
stdev 3421 53866 2.7 .8 22.8 32.7 13.3
I am left with the conclusion that using the DoD/AFM (displacement on demand - active fuel management; or whatever GM wants to call it) seems to affect the Fe wear. I say this because the 4.8L engine is the only one that does not use the fuel savings technology, AFAIK. The three other engines (5.3L, 6.0L, 6.2L) use this technology. The DoD system selectively shuts off certain cylinders by shutting down the fuel injection, and also manipulating the lifters so that they don't raise the rockers to activate the intake and exhaust valves. (See the post I had one page back that has a copy/paste of the details).
Whereas one can argue that a single UOA or series from one vehicle may skew this concept, there are nearly 4400 UOAs (four thousand four hundred) in my database now for the Vortec engine series. That's a LOT of data. And I used the ones that I can confirm by vehicle year to assure they are Gen IV engines; probably close to 500 UOAs in this study alone. All manner of variation is already accounted for. Don't complain or object because you think someone's bed load or driving style will alter the data, because I use MACRO data analysis and therefore all the variation of real world inputs are taken into account.
Looking closely at the data, the Al, Cr, Cu and Pb are all reasonably consistent across all four engine displacements. However, note that Fe is significantly higher with the three larger engines. The 5.3L and 6.0L are nearly identical in terms of all metals, in fact. The Fe in the 5.3/6.0 has a mean shift great enough that it's aligned with a stdev contrasted to the 4.8L. The 6.2L engine is two stdev outside of the 4.8L in Fe. But the other wear metals (Al, Cr, Cu, Pb) are all within a fairly tight group across all four engines. The Fe in the 4.8L engine averages around 2.7ppm/1k miles. The three larger engines with Dod/AFM are all much higher. Hence the fuel management system definitely increases the Fe wear. Folks, while we cannot conclude that the DoD/AFM is the sole contributor to higher Fe wear, we can say with confidence it is probably the main contributor to the rise in Fe wear!
Now, again, I want to emphasize that this does not mean the GM fuel economy feature is bad, or that the GM engines have a flaw. DO NOT PUT YOUR INTERPRETATION INTO MY DATA; DON'T USE YOUR WORDS TO FILL MY MOUTH. What I'm stating here is that there is clear evidence to conclude that the DoD/AFM technology is the most likely contributor to escalated Fe readings. That escalation in wear rates is not indicative of any mode of mechanical failure; it only serves to understand the phenomenon so that UOA data can be better understood.
Last edited:
dnewton3
Staff member
By the way, I forgot to add in the Fe wear rate info. Here it is, from almost 530 UOAs over a huge variety of applications, for the GM Vortec 5.3L engine:
3k mile OCI: 4.1ppm / 1k miles
5k mile OCI: 3.9ppm / 1k miles
7.5k mile OCI: 2.4ppm / 1k miles
10k mile OCI: 2.4ppm / 1k miles
15k mile OCI: 2.3ppm / 1k miles
As you can see, there's a substantial drop in Fe wear going from 5k to 7k miles, and it stays very low even after that, even out to 15k miles! If you double your OCI, from 7.5k miles to 15k miles, you don't really reduce wear rates, but they also are not going up! Hence, running the lube longer neither helps or hurt the engine past 7.5k miles, but if you double your OCI you are cutting your costs in half! And yet still getting the EXACT SAME wear protection!
This specific UOA shows Fe wear a tick above average, but not overtly out of control. Probably due to his 85% highway running; makes the DoD system come on, and as I've shown, it likely causes slightly elevated Fe wear.
Severe use or not, short trips or not, towing or not, it does not matter.
Longer OCIs make for lower wear rates.
Data does not lie, despite all the fear mongering in the owner's manual and at your local BITOG keyboard.
3k mile OCI: 4.1ppm / 1k miles
5k mile OCI: 3.9ppm / 1k miles
7.5k mile OCI: 2.4ppm / 1k miles
10k mile OCI: 2.4ppm / 1k miles
15k mile OCI: 2.3ppm / 1k miles
As you can see, there's a substantial drop in Fe wear going from 5k to 7k miles, and it stays very low even after that, even out to 15k miles! If you double your OCI, from 7.5k miles to 15k miles, you don't really reduce wear rates, but they also are not going up! Hence, running the lube longer neither helps or hurt the engine past 7.5k miles, but if you double your OCI you are cutting your costs in half! And yet still getting the EXACT SAME wear protection!
This specific UOA shows Fe wear a tick above average, but not overtly out of control. Probably due to his 85% highway running; makes the DoD system come on, and as I've shown, it likely causes slightly elevated Fe wear.
Severe use or not, short trips or not, towing or not, it does not matter.
Longer OCIs make for lower wear rates.
Data does not lie, despite all the fear mongering in the owner's manual and at your local BITOG keyboard.
Last edited:
4WD
$50 site donor 2024
Interesting - real interesting. This is a mix of Vortex V8's in various uses, regions, conventional and other lubricants?
Hey there! Just FYI the only engines that are AFM in 2014 to current are the 4.3L 5.3L and 6.2L
The 6.0 in the 2500 trucks is not AFM
The 6.0 in the 2500 trucks is not AFM
Originally Posted By: dnewton3
I did some investigation and here's what I found:
Code:
GM Vortec Gen IV engines
oil mi veh mi Al Cr Fe Cu Pb
4.8L
avg 5705 101216 2.9 .9 15.4 26.4 7.4
stdev 3240 50075 .9 .6 7.8 24.1 11.3
5.3L
avg 5721 90919 4.0 1.0 22.1 30.8 3.1
stdev 2926 53484 2.0 .6 16.0 29.8 3.7
6.0L
avg 5588 94469 3.8 .8 21.4 33.5 5.2
stdev 2522 59898 3.3 .6 12.7 28.3 6.5
6.2L
avg 5915 79385 5.6 1.4 31.1 34.6 8.5
stdev 3421 53866 2.7 .8 22.8 32.7 13.3
I am left with the conclusion that using the DoD/AFM (displacement on demand - active fuel management; or whatever GM wants to call it) seems to affect the Fe wear. I say this because the 4.8L engine is the only one that does not use the fuel savings technology, AFAIK. The three other engines (5.3L, 6.0L, 6.2L) use this technology. The DoD system selectively shuts off certain cylinders by shutting down the fuel injection, and also manipulating the lifters so that they don't raise the rockers to activate the intake and exhaust valves. (See the post I had one page back that has a copy/paste of the details).
Whereas one can argue that a single UOA or series from one vehicle may skew this concept, there are nearly 4400 UOAs (four thousand four hundred) in my database now for the Vortec engine series. That's a LOT of data. And I used the ones that I can confirm by vehicle year to assure they are Gen IV engines; probably close to 500 UOAs in this study alone. All manner of variation is already accounted for. Don't complain or object because you think someone's bed load or driving style will alter the data, because I use MACRO data analysis and therefore all the variation of real world inputs are taken into account.
Looking closely at the data, the Al, Cr, Cu and Pb are all reasonably consistent across all four engine displacements. However, note that Fe is significantly higher with the three larger engines. The 5.3L and 6.0L are nearly identical in terms of all metals, in fact. The Fe in the 5.3/6.0 has a mean shift great enough that it's aligned with a stdev contrasted to the 4.8L. The 6.2L engine is two stdev outside of the 4.8L in Fe. But the other wear metals (Al, Cr, Cu, Pb) are all within a fairly tight group across all four engines. The Fe in the 4.8L engine averages around 2.7ppm/1k miles. The three larger engines with Dod/AFM are all much higher. Hence the fuel management system definitely increases the Fe wear. Folks, while we cannot conclude that the DoD/AFM is the sole contributor to higher Fe wear, we can say with confidence it is probably the main contributor to the rise in Fe wear!
Now, again, I want to emphasize that this does not mean the GM fuel economy feature is bad, or that the GM engines have a flaw. DO NOT PUT YOUR INTERPRETATION INTO MY DATA; DON'T USE YOUR WORDS TO FILL MY MOUTH. What I'm stating here is that there is clear evidence to conclude that the DoD/AFM technology is the most likely contributor to escalated Fe readings. That escalation in wear rates is not indicative of any mode of mechanical failure; it only serves to understand the phenomenon so that UOA data can be better understood.
I wonder if the Hemi engine that cuts 4 cylinders is impacted in the same way?
I did some investigation and here's what I found:
Code:
GM Vortec Gen IV engines
oil mi veh mi Al Cr Fe Cu Pb
4.8L
avg 5705 101216 2.9 .9 15.4 26.4 7.4
stdev 3240 50075 .9 .6 7.8 24.1 11.3
5.3L
avg 5721 90919 4.0 1.0 22.1 30.8 3.1
stdev 2926 53484 2.0 .6 16.0 29.8 3.7
6.0L
avg 5588 94469 3.8 .8 21.4 33.5 5.2
stdev 2522 59898 3.3 .6 12.7 28.3 6.5
6.2L
avg 5915 79385 5.6 1.4 31.1 34.6 8.5
stdev 3421 53866 2.7 .8 22.8 32.7 13.3
I am left with the conclusion that using the DoD/AFM (displacement on demand - active fuel management; or whatever GM wants to call it) seems to affect the Fe wear. I say this because the 4.8L engine is the only one that does not use the fuel savings technology, AFAIK. The three other engines (5.3L, 6.0L, 6.2L) use this technology. The DoD system selectively shuts off certain cylinders by shutting down the fuel injection, and also manipulating the lifters so that they don't raise the rockers to activate the intake and exhaust valves. (See the post I had one page back that has a copy/paste of the details).
Whereas one can argue that a single UOA or series from one vehicle may skew this concept, there are nearly 4400 UOAs (four thousand four hundred) in my database now for the Vortec engine series. That's a LOT of data. And I used the ones that I can confirm by vehicle year to assure they are Gen IV engines; probably close to 500 UOAs in this study alone. All manner of variation is already accounted for. Don't complain or object because you think someone's bed load or driving style will alter the data, because I use MACRO data analysis and therefore all the variation of real world inputs are taken into account.
Looking closely at the data, the Al, Cr, Cu and Pb are all reasonably consistent across all four engine displacements. However, note that Fe is significantly higher with the three larger engines. The 5.3L and 6.0L are nearly identical in terms of all metals, in fact. The Fe in the 5.3/6.0 has a mean shift great enough that it's aligned with a stdev contrasted to the 4.8L. The 6.2L engine is two stdev outside of the 4.8L in Fe. But the other wear metals (Al, Cr, Cu, Pb) are all within a fairly tight group across all four engines. The Fe in the 4.8L engine averages around 2.7ppm/1k miles. The three larger engines with Dod/AFM are all much higher. Hence the fuel management system definitely increases the Fe wear. Folks, while we cannot conclude that the DoD/AFM is the sole contributor to higher Fe wear, we can say with confidence it is probably the main contributor to the rise in Fe wear!
Now, again, I want to emphasize that this does not mean the GM fuel economy feature is bad, or that the GM engines have a flaw. DO NOT PUT YOUR INTERPRETATION INTO MY DATA; DON'T USE YOUR WORDS TO FILL MY MOUTH. What I'm stating here is that there is clear evidence to conclude that the DoD/AFM technology is the most likely contributor to escalated Fe readings. That escalation in wear rates is not indicative of any mode of mechanical failure; it only serves to understand the phenomenon so that UOA data can be better understood.
I wonder if the Hemi engine that cuts 4 cylinders is impacted in the same way?
dnewton3
Staff member
Originally Posted By: Realtech214
Hey there! Just FYI the only engines that are AFM in 2014 to current are the 4.3L 5.3L and 6.2L
The 6.0 in the 2500 trucks is not AFM
I've heard that, too. I am not saying you're wrong, but I've found more than one reference that says your info is incorrect.
Looking at this, it shows the LY6 having been DoD (or AFM, or whatever we want to call it) since 2007 ... Would that not include all of GM's light duty trucks?
Read down into the Gen IV data ...
https://en.wikipedia.org/wiki/LS_based_GM_small-block_engine
LY6
The LY6 is a Generation IV small block V8 truck engine with a cast iron block. It shares the same bore and stroke as its LQ4 predecessor. Like other Gen IV engines, it features variable valve timing and displacement on demand. It generated 361 horsepower at 5,600 rpm and 385 lb-ft of torque at 4,400 rpm using "regular" gas, or ~87 octane. Redline is 6,000 rpm and compression ratio is 9.6:1. This engine uses L92 / LS3 style rectangle port cylinder heads, though without the sodium filled exhaust valves of the LS3.
Applications:
2007–present Chevrolet Silverado HD
2007–present GMC Sierra HD
2007–2013 Chevrolet Suburban 3/4 ton
2007–2013 GMC Yukon XL 3/4 ton
There are a slew of references at the bottom of the Wiki link; there are clear indications that other sources believe that the 6.0L in the HD trucks does (or at least did) have some form of AFM. They may or may not get the VVT, however ...
In the chart towards the end, it shows the 6.0L LY6 getting VVT, but not AFM; that's in direct contradiction to the quote in red above. However it also shows the 6.0L L77 as having AFM, but not VVT. Certainly at least some of the 6.0L engines got AFM, and some of them ended up in HD trucks. AFM may not be in all 2500HD 6.0L engines, but it's at least in some of them.
I'm not a GM engine expert; I don't know the genealogy that well. (I know the Dmax well, but that's about it).
However, what's readily apparent from my data is that the 4.8L engine has lower wear overall, and sources indicate it never had AFM.
Your point may or may not be true; but what is known for sure is that the 5.3L and 6.0L have higher wear, and most of them do get AFM. Essentially, the Gen IV engine was designed as an outgrowth of the Gen III, for the purpose of adding fuel management features, and Gen IV came out in 2005 or 2006 depending upon what source you want to credit.
Perhaps GM used AFM in the 6.0L HD trucks for a while, but then quit? I have no idea.
I'm not convinced you're right or wrong. Just noting that other sources contradict your info.
Hey there! Just FYI the only engines that are AFM in 2014 to current are the 4.3L 5.3L and 6.2L
The 6.0 in the 2500 trucks is not AFM
I've heard that, too. I am not saying you're wrong, but I've found more than one reference that says your info is incorrect.
Looking at this, it shows the LY6 having been DoD (or AFM, or whatever we want to call it) since 2007 ... Would that not include all of GM's light duty trucks?
Read down into the Gen IV data ...
https://en.wikipedia.org/wiki/LS_based_GM_small-block_engine
LY6
The LY6 is a Generation IV small block V8 truck engine with a cast iron block. It shares the same bore and stroke as its LQ4 predecessor. Like other Gen IV engines, it features variable valve timing and displacement on demand. It generated 361 horsepower at 5,600 rpm and 385 lb-ft of torque at 4,400 rpm using "regular" gas, or ~87 octane. Redline is 6,000 rpm and compression ratio is 9.6:1. This engine uses L92 / LS3 style rectangle port cylinder heads, though without the sodium filled exhaust valves of the LS3.
Applications:
2007–present Chevrolet Silverado HD
2007–present GMC Sierra HD
2007–2013 Chevrolet Suburban 3/4 ton
2007–2013 GMC Yukon XL 3/4 ton
There are a slew of references at the bottom of the Wiki link; there are clear indications that other sources believe that the 6.0L in the HD trucks does (or at least did) have some form of AFM. They may or may not get the VVT, however ...
In the chart towards the end, it shows the 6.0L LY6 getting VVT, but not AFM; that's in direct contradiction to the quote in red above. However it also shows the 6.0L L77 as having AFM, but not VVT. Certainly at least some of the 6.0L engines got AFM, and some of them ended up in HD trucks. AFM may not be in all 2500HD 6.0L engines, but it's at least in some of them.
I'm not a GM engine expert; I don't know the genealogy that well. (I know the Dmax well, but that's about it).
However, what's readily apparent from my data is that the 4.8L engine has lower wear overall, and sources indicate it never had AFM.
Your point may or may not be true; but what is known for sure is that the 5.3L and 6.0L have higher wear, and most of them do get AFM. Essentially, the Gen IV engine was designed as an outgrowth of the Gen III, for the purpose of adding fuel management features, and Gen IV came out in 2005 or 2006 depending upon what source you want to credit.
Perhaps GM used AFM in the 6.0L HD trucks for a while, but then quit? I have no idea.
I'm not convinced you're right or wrong. Just noting that other sources contradict your info.
Last edited:
Originally Posted By: dnewton3
Originally Posted By: Realtech214
Hey there! Just FYI the only engines that are AFM in 2014 to current are the 4.3L 5.3L and 6.2L
The 6.0 in the 2500 trucks is not AFM
I've heard that, too. I am not saying you're wrong, but I've found more than one reference that says your info is incorrect.
Looking at this, it shows the LY6 having been DoD (or AFM, or whatever we want to call it) since 2007 ... Would that not include all of GM's light duty trucks?
Read down into the Gen IV data ...
https://en.wikipedia.org/wiki/LS_based_GM_small-block_engine
LY6
The LY6 is a Generation IV small block V8 truck engine with a cast iron block. It shares the same bore and stroke as its LQ4 predecessor. Like other Gen IV engines, it features variable valve timing and displacement on demand. It generated 361 horsepower at 5,600 rpm and 385 lb-ft of torque at 4,400 rpm using "regular" gas, or ~87 octane. Redline is 6,000 rpm and compression ratio is 9.6:1. This engine uses L92 / LS3 style rectangle port cylinder heads, though without the sodium filled exhaust valves of the LS3.
Applications:
2007–present Chevrolet Silverado HD
2007–present GMC Sierra HD
2007–2013 Chevrolet Suburban 3/4 ton
2007–2013 GMC Yukon XL 3/4 ton
There are a slew of references at the bottom of the Wiki link; there are clear indications that other sources believe that the 6.0L in the HD trucks does (or at least did) have some form of AFM. They may or may not get the VVT, however ...
In the chart towards the end, it shows the 6.0L LY6 getting VVT, but not AFM; that's in direct contradiction to the quote in red above. However it also shows the 6.0L L77 as having AFM, but not VVT. Certainly at least some of the 6.0L engines got AFM, and some of them ended up in HD trucks. AFM may not be in all 2500HD 6.0L engines, but it's at least in some of them.
I'm not a GM engine expert; I don't know the genealogy that well. (I know the Dmax well, but that's about it).
However, what's readily apparent from my data is that the 4.8L engine has lower wear overall, and sources indicate it never had AFM.
Your point may or may not be true; but what is known for sure is that the 5.3L and 6.0L have higher wear, and most of them do get AFM. Essentially, the Gen IV engine was designed as an outgrowth of the Gen III, for the purpose of adding fuel management features, and Gen IV came out in 2005 or 2006 depending upon what source you want to credit.
Perhaps GM used AFM in the 6.0L HD trucks for a while, but then quit? I have no idea.
I'm not convinced you're right or wrong. Just noting that other sources contradict your info.
I can't comment about the 6.0 without some research, but I can most decidedly concur that the 2007 mid-year body changeover included the change to ALL 5.3s including AFM. Our 2009 5.3 was an unfortunate one to develop massive oil consumption due to the design infancy of the AFM lifters & PCV valve system.
Originally Posted By: Realtech214
Hey there! Just FYI the only engines that are AFM in 2014 to current are the 4.3L 5.3L and 6.2L
The 6.0 in the 2500 trucks is not AFM
I've heard that, too. I am not saying you're wrong, but I've found more than one reference that says your info is incorrect.
Looking at this, it shows the LY6 having been DoD (or AFM, or whatever we want to call it) since 2007 ... Would that not include all of GM's light duty trucks?
Read down into the Gen IV data ...
https://en.wikipedia.org/wiki/LS_based_GM_small-block_engine
LY6
The LY6 is a Generation IV small block V8 truck engine with a cast iron block. It shares the same bore and stroke as its LQ4 predecessor. Like other Gen IV engines, it features variable valve timing and displacement on demand. It generated 361 horsepower at 5,600 rpm and 385 lb-ft of torque at 4,400 rpm using "regular" gas, or ~87 octane. Redline is 6,000 rpm and compression ratio is 9.6:1. This engine uses L92 / LS3 style rectangle port cylinder heads, though without the sodium filled exhaust valves of the LS3.
Applications:
2007–present Chevrolet Silverado HD
2007–present GMC Sierra HD
2007–2013 Chevrolet Suburban 3/4 ton
2007–2013 GMC Yukon XL 3/4 ton
There are a slew of references at the bottom of the Wiki link; there are clear indications that other sources believe that the 6.0L in the HD trucks does (or at least did) have some form of AFM. They may or may not get the VVT, however ...
In the chart towards the end, it shows the 6.0L LY6 getting VVT, but not AFM; that's in direct contradiction to the quote in red above. However it also shows the 6.0L L77 as having AFM, but not VVT. Certainly at least some of the 6.0L engines got AFM, and some of them ended up in HD trucks. AFM may not be in all 2500HD 6.0L engines, but it's at least in some of them.
I'm not a GM engine expert; I don't know the genealogy that well. (I know the Dmax well, but that's about it).
However, what's readily apparent from my data is that the 4.8L engine has lower wear overall, and sources indicate it never had AFM.
Your point may or may not be true; but what is known for sure is that the 5.3L and 6.0L have higher wear, and most of them do get AFM. Essentially, the Gen IV engine was designed as an outgrowth of the Gen III, for the purpose of adding fuel management features, and Gen IV came out in 2005 or 2006 depending upon what source you want to credit.
Perhaps GM used AFM in the 6.0L HD trucks for a while, but then quit? I have no idea.
I'm not convinced you're right or wrong. Just noting that other sources contradict your info.
I can't comment about the 6.0 without some research, but I can most decidedly concur that the 2007 mid-year body changeover included the change to ALL 5.3s including AFM. Our 2009 5.3 was an unfortunate one to develop massive oil consumption due to the design infancy of the AFM lifters & PCV valve system.
- Status