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ATF change vs flush

Eureka

Eureka

Diamond Member
I've got a 2004 Camry with 70k that's started to feel a bit lunky during acceleration/decceleration (during the shifts). I figure it might be time for a ATF change.

Should I just do a simple drain and fill? I've read somewhere that if you do 3 drain and fills in a row, with appropriate mixing (60% new fluid with the 40% trapped old fluid) you'll essentially have replaced most of the old fluid. Alternatively, just do a single drain and fill.

I've also read elsewhere to remove the trans return line and have it drain as you're adding more fluid.

What's the better way to approach this?
 
LTC8K6 said:
Maybe you broke a mount?
Click to expand...

Thanks for reminding me about those... I'll do a general check. However, it's my mom's car and its usage consists about a weekly or twice a week grocery run, so I don't think the mounts are out.
 
oldsmoboat said:
They generally say flush under 100k and drain and fill over 100k.
Click to expand...

Only real reason for that is for inspection of the debris caught on the magnet inside the pan.

But if you're having a non-transmission shop do it, there's no point.

A transmission man can give you an idea of the transmission's internal health by looking inside the pan.

If you're not going to have a tranny specialist drop the pan, then do the flush...it's the superior method for actually cleaning the inside of the tranny.
 
Some auto manufacturers, including Honda, contraindicate flushing, but all approve of drain and refill.
 
I wouldn't flush my tranny unless the manufacturer says it's OK. They're increasingly complex and need specific things and pumping a cleaning agent through it might not be smart in all cases.
 
I personally have a local trans shop do a drain and fill. This includes a new filter, which you can not change unless the trans pan is removed. When they do a flush, the old filter is not removed or replaced. But a flush, will also clean out the tranny to tran cooler lines and the cooler as well.
 
I prefer a drain/fill with a pan drop if there is a filter or to see what is in the pan every 30k myself.
 
Not all modern transmissions can be flushed. I know modern toyota ones have no external fluid lines, so there is nothing to attach a flush machine to.

The fluid cooler is internal, and coolant lines run to the transmission instead.
 
The most important thing here is to ensure that whoever is doing the fluid change (whichever method you use) is using the correctly rated fluid. It is common for shops to use a cheaper fluid they get in bulk, and then using something like an ATP additive to "bring it up" to manufacturers specs. This is not advantageous to the life and function of your transmission. Ensure if someone else does this they are going to use a fluid that is nativelly certified for your spec. Transmissions are so complex now, almost the only thing I feel comfortable using is the own manufacturers fluid or something that has been actually certified to meet that spec. While I get what Amsoil says about their Multi Vehicle ATF or whatever it's called, I still don't feel comfortable using it.

And even if you bring it do a stealership, make sure they're going to use the correct fluid. They are not completely trustable either.

Chuck
 
Do what the manual says and use the fluid recommended by the manufacturer. I know it sounds obvious, but seriously, do it right. If you google your car, you'll find the instructions somewhere.

For my Accord, the procedure is to drain and fill, cleaning the magnetic drain plug, drive it until hot, then repeat 2 more times using new fluid each time. The only acceptable fluid is Honda's own ATF-Z1 or new ATF-DW1. No power flushing.
 
I flush it then drive it for about a week or so, then drop the pan an do the filter and refill. I've had flushes plug the filter up and and reduce the pressure enough that the tranny acted up worse than before the flush.
 
Drain and refill. Some people like to do the drain and refill... drive it for a few days. Drain it again and refill.

If your ATF isn't looking horrid then I wouldn't bother with the second drain/fill.
 
Most flush machines I've had anything to do with use the transmission's own pump to move the fluid through. So it's not like there's some extraordinarily high pressure that will damage your trans.

All this "drain and refill, drive, drain and refill again", is a waste of time. Do a proper flush and be done with it. Your trans will be cleaner inside than draining and refilling will ever get it.

Again, the only advantage the drain and refill has is if an experience transmission mechanic is checking the pan and magnet. And it's not terrible to change the filter occasionally, but a flush cleans that, too.

It's just ridiculous how clean a properly-done flush gets the inside of the tranny.
 
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