Mobius, what benefits are expected with the fluid switch?
7 Speed Manual Transmission Fluid Change
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Yes, I'm sure that's true in many cases.
I change out manual transmission fluid at 25,000 mile intervals and I've never had a transmission wear out. Example - I'm the original owner of a 5-speed 2005 Civic that has over 473,000 miles (Amsoil Synthetic Synchromesh Transmission fluid every 25k) and still gets 45 MPG highway (synthetic motor oil since 500 miles, changed at 5k intervals).
That's the power of synthetic oil.
I also routinely red line my C7 engine, and I think the transmission deserves some fresh oil for all of her good service, and her ability to tolerate my demands.
UPDATE: The 2005 Civic went 626,000 miles before retirement, with ZERO transmission issues.
Mobius, I will follow your research into whether our C7's will benefit from synthetic transmission oil...Yes, I'm sure that's true in many cases.
I change out manual transmission fluid at 25,000 mile intervals and I've never had a transmission wear out. Example - I'm the original owner of a 5-speed 2005 Civic that has over 473,000 miles (Amsoil Synthetic Synchromesh Transmission fluid every 25k) and still gets 45 MPG highway (synthetic motor oil since 500 miles, changed at 5k intervals).
That's the power of synthetic oil.
I also routinely red line my C7 engine, and I think the transmission deserves some fresh oil for all of her good service, and her ability to tolerate my demands.
I changed out my engine oil, 7-speed transmission fluid and the differential (non-Z51) fluid on Friday the 29th. Changing the tranny and diff fluid is easy. This work was done on my 4-post lift, which I checked for level before beginning.
For the tranny, I used Amsoil Torque Drive synthetic Dexron III. The Tremec has a published capacity of 3.7 qt, but after draining the oil and replacing the drain plug with a new magnetic drain plug* I was only able to pump in 3.25 qt before flow out from the fill hole occurred. So, I assume that about 0.45 qt is captured in the tranny and unable to drain.
For the diff, I was pleased to see that there is a magnetic factory drain plug. In fact, both the fill and drain plug on the diff are identical and both are magnetic. Since there have been issues with low diff fluid from the factory on some cars, I carefully captured the fluid for measurement. After complete draining (about an hour of slow drips) the total volume of diff fluid was 71 oz. The diff is spec'd to hold 91 oz (from Amsoil website), which is exactly how much I was able to install.
I've never had any problems with the diff over 4800 miles. The diff fluid was quite dirty, lots of fine metal, and the magnetic drain plug had a good coating of fine metal particles. This isn't unusual for the diff, given that a limited slip diff is a wet multiplate clutch system, and sheds metal from the friction plates into the oil. I replaced the factory magnetic drain plug with a new aftermarket magnetic plug* that has a much larger exposed magnet surface area and about twice the magnetic strength of the factory unit (tested by using the drain plugs to lift various weight box wrenches). I filled with the factory GM gear oil (GM P/N 88862624), which is synthetic and contains the necessary friction modifier.
I then took the car out for a quick drive to get a feel for the shifting performance. Cold shifts are smoother, but as the transmission warmed things seem about the same. Shifting quality for my car has always been good.
After getting the car to full temp, I drove roughly 30 miles, lots of shifting 1st through 5th, with light and hard acceleration. I then headed home and put the car back on the lift. I let the car cool for two hours and then checked the fluid levels. Both the tranny and diff were still warm, and after removing the fill plugs I saw a few drops of fluid emerge from both, indicating both were filled. As a double-check, and because the tranny only accepted 3.25 qt (versus the 3.7 qt spec), I tried to add another oz of fluid. The tranny wouldn't accept any more fluid, and was truly full.
I've put over 100 miles on the car since the fluid change. The car is running and shifting well. There is a subtle improvement in shift quality, mostly when cold, but the car has always shifted well. More importantly, I've got the magnetic drain plugs in place to scavenge metal particles. I placed it on the lift about an hour ago to double-check for leaks - all is good.
I'll replace the tranny fluid and diff fluid again at 25,000 miles (motor oil every 5,000 miles).
*Plugs were purchased from Custom Corvette Accessories. The plugs are listed as C6 items, but fit the C7. The diff plug is longer than stock, but has no clearance issues - I carefully checked clearance before installation. Torque specs for the tranny fill and drain lugs are 20 ft-lbs. The diff fill and drain plugs have a torque spec of 20 ft-lbs.
Images from the Shop Manual:
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For the tranny, I used Amsoil Torque Drive synthetic Dexron III. The Tremec has a published capacity of 3.7 qt, but after draining the oil and replacing the drain plug with a new magnetic drain plug* I was only able to pump in 3.25 qt before flow out from the fill hole occurred. So, I assume that about 0.45 qt is captured in the tranny and unable to drain.
For the diff, I was pleased to see that there is a magnetic factory drain plug. In fact, both the fill and drain plug on the diff are identical and both are magnetic. Since there have been issues with low diff fluid from the factory on some cars, I carefully captured the fluid for measurement. After complete draining (about an hour of slow drips) the total volume of diff fluid was 71 oz. The diff is spec'd to hold 91 oz (from Amsoil website), which is exactly how much I was able to install.
I've never had any problems with the diff over 4800 miles. The diff fluid was quite dirty, lots of fine metal, and the magnetic drain plug had a good coating of fine metal particles. This isn't unusual for the diff, given that a limited slip diff is a wet multiplate clutch system, and sheds metal from the friction plates into the oil. I replaced the factory magnetic drain plug with a new aftermarket magnetic plug* that has a much larger exposed magnet surface area and about twice the magnetic strength of the factory unit (tested by using the drain plugs to lift various weight box wrenches). I filled with the factory GM gear oil (GM P/N 88862624), which is synthetic and contains the necessary friction modifier.
I then took the car out for a quick drive to get a feel for the shifting performance. Cold shifts are smoother, but as the transmission warmed things seem about the same. Shifting quality for my car has always been good.
After getting the car to full temp, I drove roughly 30 miles, lots of shifting 1st through 5th, with light and hard acceleration. I then headed home and put the car back on the lift. I let the car cool for two hours and then checked the fluid levels. Both the tranny and diff were still warm, and after removing the fill plugs I saw a few drops of fluid emerge from both, indicating both were filled. As a double-check, and because the tranny only accepted 3.25 qt (versus the 3.7 qt spec), I tried to add another oz of fluid. The tranny wouldn't accept any more fluid, and was truly full.
I've put over 100 miles on the car since the fluid change. The car is running and shifting well. There is a subtle improvement in shift quality, mostly when cold, but the car has always shifted well. More importantly, I've got the magnetic drain plugs in place to scavenge metal particles. I placed it on the lift about an hour ago to double-check for leaks - all is good.
I'll replace the tranny fluid and diff fluid again at 25,000 miles (motor oil every 5,000 miles).
*Plugs were purchased from Custom Corvette Accessories. The plugs are listed as C6 items, but fit the C7. The diff plug is longer than stock, but has no clearance issues - I carefully checked clearance before installation. Torque specs for the tranny fill and drain lugs are 20 ft-lbs. The diff fill and drain plugs have a torque spec of 20 ft-lbs.
Images from the Shop Manual:
Here's the current mileage (as of August 31, 2014). The car still get 45MPG highway (no kidding).
.
UPDATE: The Civic hit reached the 600,000 mile mark today, January 3, 2017.
Here are the diff drain and fill plugs.
Here's the tranny drain plug (passenger side of tranny). The fill plug looks identical (no photo) and is up on the driver side of the tranny. The words FILL and DRAIN are cast into the tranny housing next to each plug, as I recall.
FYI - I used the Amsoil "pump" that screws on to the gallon jug of tranny fluid - it makes the refill easier.
My experience with synthetic transmission fluids is that on these transmissions, the factory fluid works the best.
I have friends that have put in a synthetic fluid, and the transmission did not shift as smoothly...They changed back to the GM fluid.
Also, a tip for easy fluid replacement is use air pressure to put the new fluid in... I had a plastic hand pump that fit the bottle but it broke before I could get the fluid back in the transmission, so I improvised by running the fill tube through a hole in the cap to the bottom of the bottle. Then, I ran a small air line from my compressor through hand nozzle to the top of the bottle... I could squeeze the air nozzle to control air to the bottle, being careful not to over pressure it, and still transfer a bottle in less than a minute. No fluid leaks from the bottle because the air is pushing down on the top of the fluid and forcing it up the fill tube... (Run the compressor on low pressure, 10 psi or less)
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I have friends that have put in a synthetic fluid, and the transmission did not shift as smoothly...They changed back to the GM fluid.
Also, a tip for easy fluid replacement is use air pressure to put the new fluid in... I had a plastic hand pump that fit the bottle but it broke before I could get the fluid back in the transmission, so I improvised by running the fill tube through a hole in the cap to the bottom of the bottle. Then, I ran a small air line from my compressor through hand nozzle to the top of the bottle... I could squeeze the air nozzle to control air to the bottle, being careful not to over pressure it, and still transfer a bottle in less than a minute. No fluid leaks from the bottle because the air is pushing down on the top of the fluid and forcing it up the fill tube... (Run the compressor on low pressure, 10 psi or less)
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