transmission drain and refill

"badgolferman" wrote in news: snipped-for-privacy@uni-berlin.de:

You do understand that a drain & refill only replaces about 25% of the tranny fluid at most. The recommendation using drain & refill is doing it about 4 times a year should pretty much replace all of the fluid.

You should do the differential each time, it is a seperate cavity in the 4 cylinder models and lots of fun to drain and refill! I would clean the pan and filter every other change. I think every 30,000 miles is when service is needed. If you just opened the drain plug you only got out 2-3 quarts max it holds a lot more than that. I have mine flushed out completely no cleaners are added. My mechanic removes a hose to the trans and puts it in a big bucket and while the motor is running adds new fluid as it is pumping the old out.Someone in this group did that a while back himself, maybe you can google for how he did it. My 97 has 190,000 miles shifts flawlessly. Rob

If you never had the filter changed I would change it. Also in the pan there are some magnets to collect small metal particles,these need to be cleaned also. I have a 94 with 180,000 mi. and I drain and refill the transmission at every oil change. Its only 2 qts. If your going to change the differential oil you need gear oil not ATF, a funnel and about 2 ft. of 1/2" tubing to put the oil in from the top.

The manual says the differential is transmission oil. So does the Haynes manual. Why do you say gear oil?

WHOA! wrong answer. it uses Dexron ATF, never gear oil!

The filter is important. It's only one gasket and a few more bolts but it's your car.

97

has

hard

ATF

In my opinion, this is one of those cases where 4 x 25% does not equal 100%. The remaing 75% contaminates the new 25% and so on. If the Op really wants to do his vehicles good he will spend the $70 or so and have it professionaly flushed and changed. Many of the quick lube places now have the equipment to do it, but a trans shop is the best bet.

The quick lube places disconnect one cooler line and connect there machine in series in the line. As the old fluid is being pumped out (engine running) the new fluid is being injected. Probably gets about 90% or better of the fluid. The trans shops remove the pan and install their equipment in place of the trans pickup screen. Engine is run and only new fluid is picked up and old fluid is being dumped out as it returns to the trans (pan is off while this is done). Probably gets near 100% of the fluid and actually flushes some debris in the process. Pan gets cleaned while off and new filter installed.

In my opinion, draining what fluid you can, even removing the pan and changing the filter, is a waste of time and money. Steve G.

There is no "filter" as one ordinarily considers filter media. There is a metal screen which, according to Toyota does not require replacement.

I do believe it is helpful to clean the inside of the pan though. There can be kind of slimy darkened residue clinging to it. Believe recommendation for fluid changes is 30,000 miles, so sounds like the OP is overdue. In that case, exchaning all the fluid with a machine, is a good idea, then afterward, you can keep up by simply removing the drain plug, and re filling. BTW there are three magnets stuck to the pan, so if you remove the pan you can clean those also.

Here's another idea: Just drain the fluid every time you change the oil for a while. If you change every 5,000 miles, you're changing transmission fluid six times in 30,000 miles which is equivalent to changing it all with a machine. If is helpful to clean the inside of the pan though. Just tighten the little bolts evenly and do not over tighten. It's only one gasket not really very difficult. If you look up the torque spec for the trans. pan bolts, it is given in inch pounds - divide by 12 to get foot pounds, comes out to something like 5+ ft. lbs., so you don't want to crank on them, just pull gently until you feel resistance increased. Last time I replaced the gasket, I found two bolts stripped by prior mechanic. Fortunately, those locations threaded through the case, so longer bolts solved the problem. Looks like the transmission case is aluminum alloy, so exercise caution. As previously mentioned, there is no filter. If you really wanted to go one step further you could remove the screen and clean it in solvent, but imho, if you're draining the fluid regularly, wouldn't be necessary.

Do it right, pull pan , new filter. I used Mobil Synthetic in engine , trans , differential and power steering. Mileage went up 7 MPG

Simply not true. You're assuming that mixing new with old hopelessly contaminates the new as to render it useless, whereas the truth is that by draining 42% (2.5 out of 5.9 qts.) repeatedly, all the fluid is gradually exhanged for new - fresh additives, contaminants removed, clean appearance, etc.

I agree. My math shows that after 2 drain and refills 67% is new fluid, after 3 changes 81%, and after 4 changes 89% new. Diminishing returns after that... Definitely not as good as a flush, but easier and cheaper. However, I do flush at 30k intervals, drain and refill at 15k intervals. A round of Dexron for all!

Precisely because the old oil does mix with the new - it works. Each time you're draining more of the old oil (and some of that recently added.) I do understand your point that you're never completely removing all the old particulate contaminants, and I've often heard it said that changing engine oil without changing the engine oil filter is a waste of time because the one quart (with older American cars) contaminates the other four - but in that case the particles are concentrated in the filter housing, whereas in the automatic transmission, if you drain with hot fluid, the particles are evenly distributed throughout, so you're getting more out each time and the overall mix is progressively cleaner. Three or four times, theoretically, you've gotten it all, six times even more so. Perhaps in theory there's a small percentage remaining, but not much.

Actually, I've been working on cars since 1966, including building engines, but not professionally, and have taken apart standard transmissions, but not automatic, and I'm not an argumentative guy. I agree with you that it is better to change the fluid all at once. In fact that is what I did with my own vehicle. Then decided to change to Mobil 1 ATF, and didn't want to pay $5 a quart to replace all the new fluid ('cause when they used the machine, I needed to bring 17 quarts), so I did it progressively, and that's why I calculated percent changed on refill. Actually I do both. Had the fluid exchanged (with Toyota transmission fluid I supplied), and subsequently keep it clean by regularly draining. However the official Toyota position is that only draining is required. Personally, I believe one should ensure the transmission fluid is clean as can be and at the correct level (driven minimum ten miles before final level check is what Toyota recommends, not like the shop that exchanged my fluid and had me drive around the block). Seems that most transmission problems and failures are related to neglected fluid. Recently changed the transmission pan gasket on mine and was absolutely spotless inside, magnets on the pan completely clean and free of any metal filings also. Exchanging all the fluid is best - when comparing the cost of a new transmission to the cost of "flushing" the fluid, it's always better to get the fluid clean as possible which means doing it at all at one time. I understand what you mean, that way you know it's all clean and all of the old fluid and contaminants are completely removed. Seemed like the original poster was only going to drain the fluid once, without cleaning the magnets on the inside of the pan. In that case draining several times is better. Maybe I am more argumentative that I thought, I'll stand by my original assertion that it is better to drain the transmission six times than once.

I wrote to the dealer I take my cars to and asked them to clarify their position. In the past they have also told me draining is okay.

I'm not going to drain it once. I've already done it twice in the past

10,000 miles, but maybe I should have done it more often. I'm just averse to removing the pan and messing something up. I imagine you need a new gasket and that has to be applied correctly. Even if I do remove the pan, does the screen get taken out easily; do I clean it with it more ATF or some type of solvent?

I got some prices for transmission flushing and screen cleaning and they average about $130.

Perhaps if you are averse to removing the pan and messing something up, it is best that you do not remove it. Mine was only removed to replace a leaking gasket. As previously mentioned, Toyota does not require or recommend it. Main risk, apart from stripping bolts, is that any teensy, tiny contaminants, like a fleck of dirt, can disrupt the inner workings of the valve body. Everything has to be scrupulously clean. (final rinse with solvent and air dry - never with a rag that can leave lint) Stick with just draining fluid. At least it's not being neglected, which is what tends to kill transmissions. Even if you did remove the pan, personally I'd leave the filter screen alone. Just clean the slime off the inside of the pan, clean the magnets and put them back in the same position. Gasket really shouldn't be much of a problem, IIRC it only fits one way - I didn't have any real difficulty aligning the holes in the gasket with the bolts, but the car does have to be lifted up. Not too sure it makes a big difference to pull that pan at all as long as you're changing the fluid. As I say, I've only done it when the gasket was leaking. First time, because someone installed the wrong type, and second time because someone stripped two bolts and the replacement gasket was leaking. Second time, did the work myself, used the factory gasket and all is well - but I didin't touch the filter screen it's just a metal mesh - any particles should be trapped by the magnets. Another reason I like to do my own work - there's supposed to be three magnets - I've got two - good enough though, suppose someone's got my extra magnet somewhere, maybe holding up a calendar in their service bay, who knows.

Something I like about my honda is that the drain plug has a magnet built right into the plug. So when you change the trans oil, the little metal fragments are removed.

Presumably the camry has magnets too which are inaccessible unless you take of the oil pan (actually, on my camry there is a pan inside a pan).

The stock Toyota differential drain plug is like that - small magnetic center. Would imagine with three magnets inside the transmission pan, that's considered a lifetime supply - there should never be enough metal filings to release from the magnets into the fluid. Plus each of those three magnets is significantly larger than those contained in a drain plug.

(temptation to comment disparagingly about Honda transmission problems of recent date and need for magnetic drain plug)