engine RPM @ 70mph
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From: Grand Rapids, Mi
Originally Posted by BoneZ
Alot of people get overdrive and lockup confused and i was just trying to set the record striaght. No hard feelings Archon and certainly no offense. 
Some have reported shifting problems, shuddering, and other issues when using synthetic fluid. Considering this part of the transmission'* operation...
All vehicles equipped with a 4T65-E transmission have an electronically controlled capacity clutch (ECCC) system. In the ECCC system' the pressure plate does not fully lock to the torque converter cover. It is instead, precisely controlled to maintain a small amount of slippage between the engine and the turbine, reducing driveline torsional disturbances.
may be having your transmission work in ways other than designed.
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From: South Bend, IN
Originally Posted by agrazela
Originally Posted by imidazol
As for adding synthetic oil to the motor that is not going to have any effect on the transmission shift points.
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From: Sacramento, CA WCBF '06, '07 survivor
Originally Posted by agrazela
Switch to a good synthetic engine oil (if you haven't already) and watch your cruising RPM'* drop another 100 or 200, reducing wear and saving fuel .
.at a given (70 mph) speed. but i wholeheartily agree about synthetic oil getting
better gas mileage. i've ran nothing but M1 5/30 for 135,000 miles.
ROD
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From: Grand Rapids, Mi
Originally Posted by BoneZ
I'm not seeing how a different oil can lower engine RPM'*. You would have to have a strain on the engine, or just drive slower to have lower RPM'*.
I agree. Whether you use synthetic, or dino oil, it won't have any affect on the engine rpms for a given speed.
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From: south central PA
Testy, testy, c'mon! LOL . Looks like everybody agrees that the torque converter lockup doesn't happen until the transmission oil temperature is up And it sounds like overdrive is another word for 4th gear, which it will grab even cold. What is torque converter lockup though, and how does that have the effect of another higher gear??
And it sounds like overdrive is another word for 4th gear, which it will grab even cold. What is torque converter lockup though, and how does that have the effect of another higher gear??
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From: Glendale, AZ
Here'* how I understand it:
Torque converter (TC) lockup is when the two halves of the TC are locked together to create a direct connection between the engine and transmission. During acceleration the TC is a fluid clutch between the engine and transmission, but when the car settles at cruising speed the PCM will electronically lock the torque converter. This means that instead of the impeller (input side) spinning at engine speed and transmitting torque through the transmission fluid to the turbine (output side), a clutch actually locks the components of the torque converter together at a 1:1 ratio (though as Archon pointed out, there is actually a calculated amount of slip during lockup). This greatly reduces heat in the TC and transmission fluid, because there is no longer the friction of the impeller spinning at a higher speed than the turbine. The 1:1 ratio also reduces the RPM that the engine must turn in order to move the tires at the desired rate of speed. Thus, when the torque converter clutch locks up, it may seem as if you're going into another gear because your RPMs drop by a few hundred. The net effect is a cooler transmission that will last longer, and better gas mileage because of reduced engine RPM at cruising speed.
Torque converter (TC) lockup is when the two halves of the TC are locked together to create a direct connection between the engine and transmission. During acceleration the TC is a fluid clutch between the engine and transmission, but when the car settles at cruising speed the PCM will electronically lock the torque converter. This means that instead of the impeller (input side) spinning at engine speed and transmitting torque through the transmission fluid to the turbine (output side), a clutch actually locks the components of the torque converter together at a 1:1 ratio (though as Archon pointed out, there is actually a calculated amount of slip during lockup). This greatly reduces heat in the TC and transmission fluid, because there is no longer the friction of the impeller spinning at a higher speed than the turbine. The 1:1 ratio also reduces the RPM that the engine must turn in order to move the tires at the desired rate of speed. Thus, when the torque converter clutch locks up, it may seem as if you're going into another gear because your RPMs drop by a few hundred. The net effect is a cooler transmission that will last longer, and better gas mileage because of reduced engine RPM at cruising speed.
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From: south central PA
Great explanation Ben, thanks! Lockup sounded like a mechanical connection of some type, but now I understand its a very efficient hydrodynamic transmission mode.
Always good to learn something is going to make the transmissions last longer and run cooler instead of being problematic
Do our 00-05'* also have a transmission cooler?
Always good to learn something is going to make the transmissions last longer and run cooler instead of being problematic
Do our 00-05'* also have a transmission cooler?
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From: Brampton, Ontario
Originally Posted by agrazela
Switch to a good synthetic engine oil (if you haven't already) and watch your cruising RPM'* drop another 100 or 200, reducing wear and saving fuel .
.Can someone correct me on that?
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From: Fitchburg Ma _ToastedRice_
Originally Posted by Maymybonneliveforever
Originally Posted by agrazela
Switch to a good synthetic engine oil (if you haven't already) and watch your cruising RPM'* drop another 100 or 200, reducing wear and saving fuel .
.Can someone correct me on that?