Transmission Drain/Refill questions

[The Critic]

In a recent post, Molakule stated that it'd be beneficial to do two drain/refills on a transmission that was not serviced regularly. The interesting part of his suggestion was to wait 5000 miles before draining and refilling for the second time, after the initial pan drain, pan & magnet cleaning, filter change, and refill.

He said that if one used synthetic fluid, he wanted to give the new fluid an opportunity to doing some "cleaning."

However, if one used dino ATF, would the ATF still do some "cleaning?" I'm thinking that if the transmission fluid was run for the OEM drain interval or less, couldn't one do the 2nd drain/refill within 200-300 miles, and not wait 5K before the next drain/refill? Or perhaps, could they just start the car, shift through all the gears, and let it idle for 5-10 mins?

Thanks in advance for answers to my dilemma.

Mike

 

[Gary Allan]

In your scenario ..you're merely mixing the fluid and draining ...remixing. You're giving no time to disolve/dislodge any accumulations that may be forth coming from the initial change out. If you had waited ..then any byproducts of the new fluid being introduced would be "half dumped" when you do the sencond drain/fill in 5000miles. Under your method you have new fluid that will still have the entire boatload (or whatever) of new debris ..until you swap it out again ..or it drops out in the pan ..recoaks/varnishes on the interior.

 

[Winston]

I seem to hear a lot of anecdotal evidence about putting all new fluid leading to transmission failure shortly there after. However, that is always with a neglected transmission. I think it also really depends on the type of transmission.

1. If you are within the recommended service interval (approx. 30k) then your idea of changing, waiting a 100 miles then changing again is OK.

2. If it is a neglected transmission, I would only do a partial fluid change, then wait 5k miles to do another partial change.

.02c

 

[Donald]

I think a flush is the better way to go. They push all the old fluid out and its replaced with new fluid. In addition they add a cleaner as the first thing to go through and that cleans things as its being pushed along.

You can flush your own transmission but will need 2 or 3 people.

In my case I had it refilled with Amsoil synthetic ATF and that will go for the rest of the life of my 94 Camry,

 

[The Critic]

quote:

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If you are within the recommended service interval (approx. 30k)

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Well, most OEMs now spec at least a 60K drain interval with the factory ATF. So, theoretically, any car made within the last 5 years wouldn't fall under the "neglect" category if it didn't have its first ATF service until 100K.

So, if I understood you folks correctly, it'd be normal procedure to simply drop the pan, clean pan/magnet/filter, and refill, then drive the car for several hundred miles and do another refill if the ATF was being changed at the OEM recommended interval or less? If the car was from the early 90s and the ATF was run for WAY over its recommended interval, only then should I wait 5K before doing the 2nd drain/refill?

Thanks.

 

[Gary Allan]

I was just explaining the difference between your method and the way Mola advised. The impact of one method over the other is going to vary from none to some depending on the individual unit condition.

Personally, in a sound transmission, I'd just drain via cooler line, drop pan ..change filter ...refill ...exchange via cooler lines ...add magnefine (or other auxillary filtering - magnefine being the easiest and most likely to be widely adopted by consumers) and be happy.

 

[9296D21B14]

Recent experience with this scenario. 98 Mazda Pro with 198k. Had auto transmission serviced. First time in a very long time. Don't ask how long. No excuse other than it was in my preBITOG life. Fluid black. Changed out with filter service and ARX treatment. 1200 miles later cooler line fluid replacement again yields very dark fluid. 6k later I notice the fluid darkening noticeably again. Another cooler line replacement gets it back to red. Only performance issue was a slight slipping from first to second gear briefly after the first service prior to ARX. Shifts fine now although I know it suffered from the original neglect. Fluid was either plain Walmart SuperTech or Castrol D/M3. Fingers crossed it lasts a while longer and I can now exchange transmission fluid in less than 20 minutes.

 

[Donald]

I assume that the factory fill on most new cars is synthetic ATF, thats why it can go so long? So if one wants to wait another 60K to change the ATF fluid, they better use synthetic ATF fluid also.

 

[thrace]

quote:

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I assume that the factory fill on most new cars is synthetic ATF, thats why it can go so long? So if one wants to wait another 60K to change the ATF fluid, they better use synthetic ATF fluid also.

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At least with my Honda 5spd auto in an Odyssey, the ATF is not synthetic. The last bottle of ATF Z1 I used said "petroleum oil", which is not synthetic. Unfortunately, my ATF gets quite dark after 15,000 miles even thought the recommended service is at 30K or 45K miles for the first drain and fill. I had better start saving for a transmission repair.

 

[ex_MGB]

On that Ody, check Ody Club Forum under Periodic Maintenance and look at the sticky at the top regarding the reclusive, top secret, nobody but the factory is supposed to know about, Honda ATF filter.