Transmission flush on older cars

I believe the reason for not flushing a transmission that hasn’t been flushed within the last 50,000 miles is that it can dislodge sediment that can then clog a fluid passage and cause the transmission to malfunction and require an overhaul. Vacuuming out the fluid may be different.

Have you considered dropping the pan every 60k miles and then adding your own drain plug so that you can just drain and refill the fluid ever 20k miles or so? I recommend removing the pan at least every 60k so that you can clean out the pand and the last bit of ATF where all the sediment resides.

Transmission fluid change horror stories may be partially be due to modern ATF being thinner than the the previous version ATF, yet the bottle still claims to be compatible with the older version. It may meet the lubrication requirements of Dexron 3 but it is still too thin! Putting thinner ATF in your transmission can cause a lot of problems in a worn out transmission even though you can get away with it if it’s in good condition. A bottle of ATF is ONLY the newest specification listed on the bottle. Dexron 4 is only Dexron 4 and not Dexron 3. If you need Dexron 3 buy only Dexron 3 and make sure it does not say Dexron 4 on the bottle. Anyway that’s where these don’t change your transmission fluid stories probably come from. I’ve done it and the transmission would no longer shift smoothly with Dexron 4.

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Thank you.

That’s entirely possible, but if the transmission is in that state, imo it’s better to face the music now rather than waiting for the transmission to fail while on the road. And you know when it fails it’s going to be dark, cold, and raining.

Or just wipe out the pan every 20k miles and change the fluid every 10k. Then it won’t wear out as fast and the sediment build up will be too slow to worry about. Transmissions have failed at 120k from flushing that would have otherwise gone on to 250k and started to wear out normally if it had just been left alone with no fluid change at all.

If often takes a few days or weeks to fail after flushing too.


We know who the transmissions experts are now!


Nonsense , those transmissions were going to fail anyway.


Agreed with Volvo-V70.

Even 100 MIcron particles are irrelevant as that size is less than the thickness of a sheet of printer paper.

yeah, listen to tester. I’d drop the fluid, drop the pan, clean it out completely (the pan) and put a new filter in. You can get one from the dealer (and pay more but it’s OEM) or go rock auto/autozone/advanced auto. Then close it up, add fluid (assuming you have a dip stick), drive it a day and then drop the fluid only and do that a total of 3X after the filter change. That will get about 92% of the old fluid out (will waste new fluid but…). I change my trans fluid extremely often to avoid doing it 3 to 4X at a time. Never had a trans in my toyotas go out on me.

look at your manual and it will tell you fluid for a drop (assumes filter change I believe). then look online to see total volume of trans. Say if it’s 7 qts total and 3.5 qts drop, you need 3 or 4. (1 does 50%, 2 does 75%, 3 does 87% and 4 does 94%). Hope this helps.

I got scammed by a Mr. Transmission on a 1989 grand am. A $3 part which was replaced by a reputable local transmission place solved the problem. I went to a Mr. Trans place 1st due to an ad in the yellow pages. They took the trans out, showed me metal shavings and charged me 1500 bucks (this was in 1992 or so). Then they put it back together and it still wasn’t fixed (lockup gear wouldn’t go into overdrive due to a 3 buck switch). The independent trans shop said sue in small claims court. There were like dozens of cases pending on this Mr. Trans shop. I left the city and gave up. Never again.

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does a 2014 toyota avalon hybrid have a filter inside the tranny, and a way to drop the pan
to get to it?

I doubt it. It doesn’t have an automatic transmission, exactly. It has a planetary gear set used as a ‘power split device’. There is fluid to be changed, but make sure it’s exactly what’s specified for that hybrid.

at 87k, the fluid has been changed twice.
no solvents, no inside access.

does this type of “transmission” have a filter to change?
should it also be treated with cleaners/solvents?

I doubt it has a filter, and I don’t use any chemicals on mine. No need.