Trans fluid flush vs drain and filter

[Logan Lanfear]

Ive read that flushing the fluid out of a 4L60e can damage it.  Others say just to drop the pan and change the filter and refill the trans.  What are the pros and cons of each? What would you reccomend for fluid for a 1998 4L60e with 185k?

[onecrazyfoo4u]

I'll be doing a pan drop and filter change soon.  I've always heard the same, avoid the flush method...

[OZRY83]

If you've ever dropped a pan on transmission and seen all the stuff at bottom, think of that getting pushed around your transmission by the flushing methods.

   I prefer dropping pans and changing filters myself. But I would also recommend replacing pan with one that has a drain plug. Ones that don't can be messy trying to get drained.

[OZRY83]

Flushing does get the fluid out of torque converter that draining cant do

 

[OZRY83]

also flushing can do the cooler in radiator and the lines.

   I just did my transfer case and transmission, but an 88 700R4 and 241C, used Valvoline high mileage (red Bottle) synthetic Dexron/Mercon, was on sale at Advance Auto.

[Grumpy Bear]

I did the math for this in a similar thread but bottom line is it takes multiple dump and flush to change 93.75% of the fluid. On the 6L80E about three, six quart changes or 18 quarts. Drive a few hundred miles between each dump. Change the filter on the first dump.  A power flush would take about a 48 gallon drum to dilute to the same end point. Power flushes rarely use more than a case of fluid. If this is hard to get your head around try this;

 

Put a full glass of milk in the sink and slowly let the faucet run into it overflowing and observe how many gallons of water it takes to get the milk out of the glass. 

 

I would need to know the trans capacity and the service fill volume to get a number of services for your box. 

[NSSANE02]

Drain and filter is more than enough. You don't need to get every last drop out, even swapping 50% would make a big difference in wear/longevity.

[dna9656]

This is how I do it, it costs a little more but what price peace of mind?

I get a 5-gallon bucket (like paint comes in) all the tools you'll need, rags, and enough trans fluid to replace all the fluid in the trans and converter. Remove the pressure line from the transmission oil cooler and aim it to the 5-gallon bucket, get a helper ready with transmission funnel and have all the new bottles of fluid open and ready to go, suggest you keep the new bottles on a stand and not on the vibrating vehicle, the bottles are sure to spill if left on the vehicle. Start the engine, trans fluid will start to come out of the pressure line immediately. Pour new fluid into the trans. using the trans funnel. keep up with the fluid pumping out of the pressure line. When fresh fluid exists the pressure line shut off the engine, reconnect the pressure line, drain the tranny pan, remove the old filter, clean the pan, make sure the gasket surface of the tranny pan is flat, clean the pan again, install new filter, clean the pan again, then install the gasket and pan in accordance with GM/Goodwrench service instructions and carefully torque the bolts down. Put fresh fluid in the tranny until it shows(to avoid over-filling) on the dipstick. Start it up, give it a few seconds to draw the new fluid up and check the fluid level. Check for leaks. Add fluid as necessary. Now so far as I know you just changed ALL the fluid. If you don't get it all using this method you sure get most of it.

[CKNSLS]

At a dealer the rule of thumb is a flush for transmission service.  They do not-unless requested drop the pan and change the filter.  

 

 

[HammerHead0313]

I drop the pan every 25k on every auto tranny I've owner and I never had a transmission problem. Drop the pan, replace filter, bolt the pan up, top off fluid;  Pease of mind. 

[lryfer]

I am at 95K miles on the 07 Classic Silverado and starting to change fluids that I know I can do.  Completing the diffs and t-case this weekend. 

Tranny service dealer told me today they only flush and don’t change the filter as their machine cleans the filter during the flush.  Told them I have heard horror stories after flush and was told that was years ago.  Now new machine no issues and it cleans the filter as well without removing pan.  Also, they told me dropping pan and change filter costs more than the 250.00 flush.  So, looked at tranny but don't know if I can do it or not.  Just got truck in my garage and will need to put on jack stands.  What is the process or troubles dropping the pan and getting it back on?  I see the exhaust may need to be disconnected from manifolds.

[txab]

22 hours ago, lryfer said:

I am at 95K miles on the 07 Classic Silverado and starting to change fluids that I know I can do.  Completing the diffs and t-case this weekend. 

Tranny service dealer told me today they only flush and don’t change the filter as their machine cleans the filter during the flush.  Told them I have heard horror stories after flush and was told that was years ago.  Now new machine no issues and it cleans the filter as well without removing pan.  Also, they told me dropping pan and change filter costs more than the 250.00 flush.  So, looked at tranny but don't know if I can do it or not.  Just got truck in my garage and will need to put on jack stands.  What is the process or troubles dropping the pan and getting it back on?  I see the exhaust may need to be disconnected from manifolds.

Plenty of videos on Youtube. Just search.

 

Here's one search for you

 

https://www.youtube.com/results?search_query=2007+silverado+classic+transmission+fluid