GM transmission maintenance - this or that?

[trinacriabob]

I've got the GM 4T65-E transaxle in my LaCrosse.

Whether on this car or my last car (4T60 transaxle), I've never had a transmission flush, where they leave the pan/gasket/filter alone.  I've always had them drain and refill the transmission, and have them change the filter and check the pan and gasket in the process. 

I am aware that that leaves some old fluid in the torque converter.  However, an old school GM advisor told me that doing "drain and fill" with the pan and gasket dropped every couple of years - 25,000 or 30,000 miles - is as good as doing the full flush with the machine less often.  He said the "drain and fill" is easier on the transmission.

I've had coolant, brake fluid, and power steering fluid flushed and that's done by a machine that they hook up to the car.  I haven't had problems from those flushes.  At least not yet.  The transmission flush also uses a machine.  Because transmissions are real complicated (from seeing the cutaways), I am concerned that the flush could be harmful to seals, servos, and whatnot.  But, then again, the machine should run at a speed and pressure that is correctly calibrated and does the job since they've offered this service for years.  I've actually heard that the flush is harmful when an automatic transmission has been neglected, the fluid is in bad shape, and, finally, someone gets around the flushing it when the car is older.  My car is "older," I guess, but has low miles and the fluid has been changed a few times.

Which method do you use and do you have opinions about either method?  Have you tried both, or switched? 

If you've done the flush, how has that worked out? 

Thanks.

 

[G. David Felt]

Kirkland Transmission who I use for all my tranny work pulls the gasket and filter and breaks it open to see the condition of the trans, they still also flush it to get all old fluid out of torque converter. 

For me, having it all replaced and flushed seems to give me solid long life.

[trinacriabob]

8 hours ago, dfelt said:

Kirkland Transmission who I use for all my tranny work pulls the gasket and filter and breaks it open to see the condition of the trans, they still also flush it to get all old fluid out of torque converter. 

For me, having it all replaced and flushed seems to give me solid long life.

Seems like a hybrid job (flush and drain/fill).  They sound like one of those stalwart shops.

So, then, I guess you've had these flushes which also involved a machine and you've motored along some 20,000 or 30,000 miles after the fact without any hassles !?  That's great.

[G. David Felt]

1 hour ago, trinacriabob said:

Seems like a hybrid job (flush and drain/fill).  They sound like one of those stalwart shops.

So, then, I guess you've had these flushes which also involved a machine and you've motored along some 20,000 or 30,000 miles after the fact without any hassles !?  That's great.

Yup, They have done all my autos and my kids.

Daughters 1999 Durango has 265,000 miles and still going strong

My 1993 GMC SLE Suburban over 300,000 miles and still going strong

My 2006 Escalade SVA Platinum 140,000 miles and still strong

So yes, the machine are fine and I have not had any shortness of life from using them to flush the entire system of a tranny.

[trinacriabob]

12 hours ago, dfelt said:

So yes, the machine are fine and I have not had any shortness of life from using them to flush the entire system of a tranny.

Ok. so I'll try this approach the next time and then might return to "drop pan, drain, change filter, and refill" as the car gets older.  I think I'll try this.  It's been an available service for a long time.  Thanks.