Ok, as a 4L60E owner, who has serviced his own transmission at 135k miles, and had it live to tell the tale 60 miles later, here goes:
1. There is absolutely, positively nothing wrong with using Maxlife in these trannies. I give a rat's ace what anybody has to say about it. It's in there, and it works, and we'll.
2. Do the pan drop, and then flush the entire capacity. Flushing this Trans is 10 times easier than dropping the pan, so if you're already in for the penny, go for the pound.
3. Any automatic Trans is going to experience higher levels of contaminants immediately following a fluid change. Add a Magnefine, and don't worry about it.
From the mind of a transmission specialist, and 4L60E owner:
Quote:
Cliff Notes:
1. The 4L60E uses detergents in the fluid to collect dirt. The pore sizes of the filter are too big to collect the fine stuff.
2. Flush the fluid regularly (every other oil change) to keep the trans clean. It takes about 10 quarts.
3. Repeat the flush as soon as the fluid looks dark again (could be 500 miles, could be 10000 miles). VERY IMPORTANT TO WATCH THE FLUID CONDITION.
4. Change the filter once, then just flush it after that.
This question has been asked countless times: "I have a high mileage car where the transmission fluid has probably never been changed. Should I change it?"
There seems to be no consensus on this answer, and the people that say you shouldn't will cite numerous anecdotal cases of transmission failure within a short time following a flush. They usually cite reasoning along the lines of this article where the new fluid is "too slick and causes slippage whereas the old fluid held everything together." This answer never satisfied me as it didn't seem to properly explain what was happening on a molecular or chemical level. Furthermore, transmission fluid detergents are intentionally designed NOT to remove the friction material from clutches (actually, it's antifreeze that does that job quite well, FYI!). To top that off, the actual "friction" within an automatic transmission is not abrasive friction of clutch against steel but molecular friction along with a very thin fluid film between the parts that has been carefully engineered to provide grip with a minimum of wear. Heat usually causes more damage to transmission clutches and steels than abrasive friction, so the idea of "slick new fluid" hurting an old trans never made sense to me.
Gregg Nader of Sonnax has been doing research on this with the help of fluid contamination analysis equipment and recently I had a conversation with him about it. He has given me permission to share this information with you. Please feel free to read and consider. I am quoting and paraphrasing as we had several conversations about it. Gregg, if I misstate anything, please correct me.
FILTRATION IN THE 4L60E
Filtration is accomplished via two methods: the filter, and the fluid.
The Pan Filter
The 4L60E uses a filter on the suction (intake) side of the pump. This means that the pump relies on ambient atmospheric pressure (14.7psi at sea level) to push down on the fluid which then can flow up through the filter and into the pump. As you know, the finer a filter is, the more pressure drop it causes for a given flow rate. A suction side filter is limited to a pressure far below 14.7psi in order to flow enough to supply the pump. Since the fluid is thicker when cold, this is the worst-case scenario for the transmission filter - it must flow enough so that it doesn't starve the pump during cold starts. This means that the filter cannot be as fine as one might like. In fact, the pan filter's main job is to keep large debris from getting into the pump where it can do a lot of damage (and even this is sometimes in question based on some of the gouged pumps Dustman and I have seen). This, coincidentally, is why the EPC solenoid filter in the spacer plate often gets completely clogged and collapses shut: it is the most stringent filter in the whole transmission and will catch things the pan filter passes.
Detergent Fluids
To compensate for this, the transmission fluid contains a high level of detergents (similar in operation to dish detergent). The detergents collect any dirt or grit and hold it suspended in the fluid. This grit then circulates around in the transmission. When the detergents begin to chemically break down, they can no longer hold the dirt in suspension and it then falls out of the fluid, onto the pan, and into the countless nooks and crannies inside the transmission. The fluid itself actually remains fairly free of grit (verified by Gregg's equipment) albeit dark in color (due to oxidation (chemical breakdown) of the chemical additives such as detergents) unless the resting grit is physically disturbed by fluid flow or spray. The problem is that this grit can accumulate around shift valves, inside piston cavities, etc. and cause sluggish shifting or abrasive wear of those bores.
REGARDING THE FLUSH
1. A "fluid flush" at a service center is really more of an "exchange." It is not a flush in the way that you might clean out a cooling system with some sort of special chemical or heavy detergent. There is no special process with these machines that the vehicle owner could not accomplish himself.
2. Gregg: "I discourage fluid exchanges at service centers, mainly due to concerns of cross contamination from the vehicle that was previously flushed, poorly maintained equipment or mistakes by tech. A hose from a cooler line to drain pan while pouring in new fluid is my preferred method."
So what happens if I replace the fluid with new fluid?
Gregg: "When fresh oil is introduced during a service or repair, a fresh load of detergents will pick older settled/compacted particles up and circulate them throughout the system. I have tested and verified this effect in my shop. In a normal working transmission that has never seen a failure with 100K miles, The old/original oil tested relatively clean, the new oil tested clean, 90% of the old oil was changed via drain and fill without pulling the pan. Follow up tests after 10 miles, 80 miles, and 200 miles showed the particulate matter in the oil steadily rising confirming the old concern of servicing older transmissions. In this case the transmission is now running with a greater amount of particulate circulating with the new oil than it was with the old oil.
Gregg continues: "Based on my experiences here, my recommendations for servicing older transmissions that have not had regular maintenance is as follows. Assuming a ‘normal’ service interval of once a year for a vehicle that has never or rarely had a transmission service:
1. Change the fluid and/or filter by any method. (Joel: A step-by-step process for GM B-bodies is here. Add a drain plug if you like.)
2. Relatively soon afterwards, drain the fluid and replace with new fluid. Leave the filter alone.
3. Thereafter, adopt an accelerated service interval by performing drain and fill of transmission fluid whenever changing engine oil (or every other depending on frequency).
4. After a few drain and fill services, return to the ‘normal’ service interval of once a year.
Gregg notes: "Obviously this is not practical for many customers and difficult to manage in the real world. The main point here is not the specific time, or intervals, rather if you truly want clean fluid you will need to also change out the “new” fluid added to older transmissions as it will quickly pick up the old grit that was laying around inside and the only way to get rid of this is to swap the fluid out."
Joel: One other note: If you are looking at a used 4L60E from a junkyard, remove the pan and see how much grit is laying on the bottom of the pan, on the magnet, and on the top of the filter (remove the filter and look at it). If it's clean (and wet, not dry like if someone cleaned it and then reassembled it to try to misrepresent it!), then it's likely that it was maintained.
Final note: Old transmission fluid can be recycled at any place that also accepts used motor oil.
The flush procedure:
Quote:
Cliff Notes:
1. The 4L60E uses detergents in the fluid to collect dirt. The pore sizes of the filter are too big to collect the fine stuff.
2. Flush the fluid regularly (every other oil change) to keep the trans clean. It takes about 10 quarts.
3. Repeat the flush as soon as the fluid looks dark again (could be 500 miles, could be 10000 miles). VERY IMPORTANT TO WATCH THE FLUID CONDITION.
4. Change the filter once, then just flush it after that.
This question has been asked countless times: "I have a high mileage car where the transmission fluid has probably never been changed. Should I change it?"
There seems to be no consensus on this answer, and the people that say you shouldn't will cite numerous anecdotal cases of transmission failure within a short time following a flush. They usually cite reasoning along the lines of this article where the new fluid is "too slick and causes slippage whereas the old fluid held everything together." This answer never satisfied me as it didn't seem to properly explain what was happening on a molecular or chemical level. Furthermore, transmission fluid detergents are intentionally designed NOT to remove the friction material from clutches (actually, it's antifreeze that does that job quite well, FYI!). To top that off, the actual "friction" within an automatic transmission is not abrasive friction of clutch against steel but molecular friction along with a very thin fluid film between the parts that has been carefully engineered to provide grip with a minimum of wear. Heat usually causes more damage to transmission clutches and steels than abrasive friction, so the idea of "slick new fluid" hurting an old trans never made sense to me.
Gregg Nader of Sonnax has been doing research on this with the help of fluid contamination analysis equipment and recently I had a conversation with him about it. He has given me permission to share this information with you. Please feel free to read and consider. I am quoting and paraphrasing as we had several conversations about it. Gregg, if I misstate anything, please correct me.
FILTRATION IN THE 4L60E
Filtration is accomplished via two methods: the filter, and the fluid.
The Pan Filter
The 4L60E uses a filter on the suction (intake) side of the pump. This means that the pump relies on ambient atmospheric pressure (14.7psi at sea level) to push down on the fluid which then can flow up through the filter and into the pump. As you know, the finer a filter is, the more pressure drop it causes for a given flow rate. A suction side filter is limited to a pressure far below 14.7psi in order to flow enough to supply the pump. Since the fluid is thicker when cold, this is the worst-case scenario for the transmission filter - it must flow enough so that it doesn't starve the pump during cold starts. This means that the filter cannot be as fine as one might like. In fact, the pan filter's main job is to keep large debris from getting into the pump where it can do a lot of damage (and even this is sometimes in question based on some of the gouged pumps Dustman and I have seen). This, coincidentally, is why the EPC solenoid filter in the spacer plate often gets completely clogged and collapses shut: it is the most stringent filter in the whole transmission and will catch things the pan filter passes.
Detergent Fluids
To compensate for this, the transmission fluid contains a high level of detergents (similar in operation to dish detergent). The detergents collect any dirt or grit and hold it suspended in the fluid. This grit then circulates around in the transmission. When the detergents begin to chemically break down, they can no longer hold the dirt in suspension and it then falls out of the fluid, onto the pan, and into the countless nooks and crannies inside the transmission. The fluid itself actually remains fairly free of grit (verified by Gregg's equipment) albeit dark in color (due to oxidation (chemical breakdown) of the chemical additives such as detergents) unless the resting grit is physically disturbed by fluid flow or spray. The problem is that this grit can accumulate around shift valves, inside piston cavities, etc. and cause sluggish shifting or abrasive wear of those bores.
REGARDING THE FLUSH
1. A "fluid flush" at a service center is really more of an "exchange." It is not a flush in the way that you might clean out a cooling system with some sort of special chemical or heavy detergent. There is no special process with these machines that the vehicle owner could not accomplish himself.
2. Gregg: "I discourage fluid exchanges at service centers, mainly due to concerns of cross contamination from the vehicle that was previously flushed, poorly maintained equipment or mistakes by tech. A hose from a cooler line to drain pan while pouring in new fluid is my preferred method."
So what happens if I replace the fluid with new fluid?
Gregg: "When fresh oil is introduced during a service or repair, a fresh load of detergents will pick older settled/compacted particles up and circulate them throughout the system. I have tested and verified this effect in my shop. In a normal working transmission that has never seen a failure with 100K miles, The old/original oil tested relatively clean, the new oil tested clean, 90% of the old oil was changed via drain and fill without pulling the pan. Follow up tests after 10 miles, 80 miles, and 200 miles showed the particulate matter in the oil steadily rising confirming the old concern of servicing older transmissions. In this case the transmission is now running with a greater amount of particulate circulating with the new oil than it was with the old oil.
Gregg continues: "Based on my experiences here, my recommendations for servicing older transmissions that have not had regular maintenance is as follows. Assuming a ‘normal’ service interval of once a year for a vehicle that has never or rarely had a transmission service:
1. Change the fluid and/or filter by any method. (Joel: A step-by-step process for GM B-bodies is here. Add a drain plug if you like.)
2. Relatively soon afterwards, drain the fluid and replace with new fluid. Leave the filter alone.
3. Thereafter, adopt an accelerated service interval by performing drain and fill of transmission fluid whenever changing engine oil (or every other depending on frequency).
4. After a few drain and fill services, return to the ‘normal’ service interval of once a year.
Gregg notes: "Obviously this is not practical for many customers and difficult to manage in the real world. The main point here is not the specific time, or intervals, rather if you truly want clean fluid you will need to also change out the “new” fluid added to older transmissions as it will quickly pick up the old grit that was laying around inside and the only way to get rid of this is to swap the fluid out."
Joel: One other note: If you are looking at a used 4L60E from a junkyard, remove the pan and see how much grit is laying on the bottom of the pan, on the magnet, and on the top of the filter (remove the filter and look at it). If it's clean (and wet, not dry like if someone cleaned it and then reassembled it to try to misrepresent it!), then it's likely that it was maintained.
Final note: Old transmission fluid can be recycled at any place that also accepts used motor oil.
