oil additive and trans oil change

[coxfmly]

Hello,
Couple of things....
any thoughts on using oil additives such as Z-max?

Also, I'm looking into having my trans serviced.
one shop said they will connect lines to my trans and flush the torque converter while another shop said that's not a good thing?

My sub has 220 K....

Thanks

[DmaxMaverick]

Either tranny flush is fine, as long as the machine, or the engine, pumps out the old fluid. If you're a DIY'er, it's an easy process you can do in your driveway, no machine.

If you use an oil additive (which isn't necessary, IMO), use STP, RED bottle, about 1/2 the recommended dose. You only want the added ZDP (the rest is snake oil), and you'll get enough with that.

[coxfmly]

Hi Dmax,
Is their a way of completely changing all of the the trans oil at home? Ive never had the system flushed at a shop, usually drop the pan in the backyard. Haven't had the desire to dive under the rig but the price might force me to.

Would you recommend any special fluids or additives for the trans? Anything other than fluid, pan seal and filter for a backyard service?

planning a trip up the 99 to Tahoe, trying to cover all bases....

Thanks again....

[DmaxMaverick]

You can do the entire process in your driveway/yard. It's best to do it with help, but it can be done solo (I do, most of the time).

I recommend using a quality synthetic ATF (Amsoil, Mobil 1, etc.). The age/mileage on the tranny shouldn't be considered, if it works, it works. NO additives. If you MUST, and INSIST on an additive (some folks do, for some reason), use ATF. It's a great additive for other automotive uses, so it should work well in the tranny, too.

Perform a "normal" service, pan/filter, etc.

Remove the "from radiator/cooler" line at the tranny. Install a length of clear flexible tubing (vinyl is OK, and it should fit snug on the flare, or clamp it) to the line from the radiator (leave the bung on the tranny open). If you are solo, use a length long enough so you can see the end of it, routed into a large container (5 gallon bucket, oil drain pan, etc.), from the driver's seat. Secure the end of the line to the container, so it won't flip off when fluid flows from it. If you have a helper, he/she can hold the line and watch the line for bubbles.

Fill the tranny with the normal fill amount for the pan, plus 1-2 qts, with the new fluid.

Sit in driver's seat, start the engine, allow to idle until you see bubbles in the line. Shut off engine. Fill again, same as before. Repeat until the system capacity has ran through (plus 2-4 qts. overrun), MINUS the last fill, which should be about the amount of the pan capacity (poor in the LAST fill after the next step).

Reinstall the cooler line to the tranny, and complete the service as you normally would (picking up like you'd just installed the pan). Fill with the initial fill and idle the engine, checking for leaks. Cycle through the gear range (P-N-D, D-N-P) slowly several times to purge initial air bubbles. Remaining air will purge once you put it back into service, but shouldn't be much at all. Once the fluid is warm, check the level and add as necessary. Check again once a day, for a few days, to account for any remaining air that's purged. Most often, it won't be noticed on the dipstick.

Done.

Also note, you can do this with any common automatic transmission.