Auto trans fluid change/flush (Boxster content)

Auto trans flush

OK, I find myself in the odd position of owning an automatic. The couple I’ve owned before were both boring family haulers. One I sold before 50K miles and the other I had lifetime free oil changes at the dealer so I just paid the money when the time came to do the trans while it was in.

Now I own the Boxster. While the engine is only 20K miles old the auto trans has 78K miles on it and I can’t find a record of the fluid being changed. The 101 projects book only talked about changing the filter and the oil you can drain out. That means you are only changing 50% of the fluid at best. If do it again in say another 10 or 20K miles I’ll still only have changed 75% of the oil. Is this one time when it’s worth paying a shop who can actually flush the fluid and change 100% of it in one go?

BTW, yes I know Porsche trans have to use a certain type of overpriced oil with Porsche on the bottle or more reasonably priced Esso LT 71141 or Pentosin ATF-1. Would it be worth even taking it to shock, horror, the dealer!!

Another way to do it, and get much more of the oil out, is via the coolant line.

Disconnect the coolant line going to the cooler and aim it down into a large catch basin. Start the car, and let it pump atf fluid into the catch can. When it gets down near empty, the flow will reduce to a trickle. Add more fluid through the filler and let that pump through the unit and out. You can even learn to balance the flow of what you're pouring in to what is being pumped out.

Do this with a few gallons of fluid, until the stuff coming out looks very similar to the stuff you are pouring in.

Stop. Put the hose back on. Fill the transmission.

You now have a transmission with nearly 100% new fluid.

Some are indeed terrified of this technique, and are convinced all kinds of transmission horrors will ensue. I have not found that to be the case. I am smart enough to not drive while doing this. The few seconds the unit may spend with fluid low in the box never has caused me troubles.

It's messy, takes a fair bit of fluid, but has served me well over the years.

Dont ever do a power flush at a shop. Do the method mentioned above letting the trans pump its own fluid. i have never heard of someone who had one done an the trans didnt randomly go out a few thousand miles later. And they werent going bad in the first place they were like you thinking "oh i should change the fluid". Myself included, when i was 15 dad took my first car in for an oil change and they talked him into a flush, two weeks later it was toast

There's an even wussier method I have employed. Pump a quart out, put a quart in. Repeat until you feel good about the stuff coming out. But that was with a Chrysler, using regular priced ATF, where the stuff in the box was visibly unclean.

The German secret sauce is a different price tier (but I see you have an alternative you're comfortable with, so I'm brining it up). Sounds like you have enough miles on the current fluid that it will be visibly nastly.

In reply to foxtrapper:

In relation to this, does anyone know if it will suck from the return line? Can I stick the return in a gallon of fluid and have it go back to the trans at the same time its getting pumped out from the into the cooler line?

As someone who does these evil transmission flushes for a living most modern machines are called fluid exchangers and just maintain the same pressure that there receiving from the transmission itself.

The issue you run into with the porsche requiring the fluid it does is someone whos actually willing too flush there machine and lines before adding your fluid too it. Otherwise you will likely end up with a quart of whatever universal fluid they use mixed in with yours.

Every vehicle i own including my 78 zephyr has been flushed with our machine with no negative impacts. Some people are really stuck in the 70s about transmission flushes.

You can opt to have it done with a chemical cleaner included or just fluid run through. We pump 16 quarts total in an 8qt system flush.

In reply to dropstep:

That's an excellent point, so for once if I paid to have it done, do it at the dealer where there machine is already full of the correct spec fluid.

Leaning towards DIY right now though

java230 wrote: In reply to foxtrapper: In relation to this, does anyone know if it will suck from the return line? Can I stick the return in a gallon of fluid and have it go back to the trans at the same time its getting pumped out from the into the cooler line?

Don't know. I have my doubts, but I don't know with any certainty.

Typically I have a funnel and hose up top, and just pour in after the drain flow starts to sputter. ATF of any type isn't a thick fluid, so it pours in quickly.

foxtrapper wrote:

java230 wrote: In reply to foxtrapper: In relation to this, does anyone know if it will suck from the return line? Can I stick the return in a gallon of fluid and have it go back to the trans at the same time its getting pumped out from the into the cooler line?

Don't know. I have my doubts, but I don't know with any certainty. Typically I have a funnel and hose up top, and just pour in after the drain flow starts to sputter. ATF of any type isn't a thick fluid, so it pours in quickly.

But with the boxster you have to fill from the bottom not the top. The fill plug is in the pan same as the drain. You fill through this little tower and wait for it to spill out.

I'll check with the guys tomarrow, but i don't think we "flush" these.

In reply to dropstep:

I can only ASS-u-me you were talking about me being stuck in the 70's. My car was a 92 and this happened in 08. Other than you, I haven't heard of a good report on a trans flush.

Watch the wheeler dealer episode on the auto boxster they did.

If the fluid in there now looks good there's nothing wrong with just pan dropping it. Does Porsche tell you do anything more than that?

Adrian_Thompson wrote: But with the boxster you have to fill from the bottom not the top. The fill plug is in the pan same as the drain. You fill through this little tower and wait for it to spill out.

Well that looks like a messy pain in the butt.

I'd say you could still do it though. Either from below with a pump, or from the top with gravity.

I'd probably like the idea of buying a $5 Harbor Freight electric drill pump to add oil. So I'd buy one.

Suspect I'd be turning the engine off once the transmission flow sputtered, filling until overflow, turning the engine back on until flow sputtered, repeat.

I think amesoil makes a European trans fluid you could use.

Sorry for the delay. We just drop the pan, change filter and refill.

In reply to Gearheadotaku:

Sweet, then I'll do the same.......Once I get the car back

Adrian_Thompson wrote: In reply to Gearheadotaku: Sweet, then I'll do the same.......Once I get the car back

Just understand, that's about a 50% fluid change. All the old fluid in the torque converter stays there, to contaminate the new fluid.

It's not inherently bad. It's just not a complete fluid change, and is not a flush.