Transmission fluid change question

[Thomas]

Hello everyone!

I’m new to the forum, but have been watching Eric the car guy for a while now. All of the information he has been very detailed and I feel like I’ve learned a lot from watching it.

In some of his transmission fluid videos he says that changing the fluid could potentially damage the transmission if it’s old enough. I have a 2009 1.8L Honda Civic with ~86k miles on it and a 2009 3.5L Toyota Sienna with ~96k miles on it and I was just wondering if there was a cut off or anything like that for this potential transmission failure. I was told that the transmission fluids need to be changed on both my vehicles, but I didn’t want to jump right into it without getting an opinion first.

Thanks for the help!

Topic

[college man]

here is an answer.

http://www.ericthecarguy.com/faq/solving-transmission-problems?start=5#IfIDontChangeMyAutomaticTransmissionFluidforaLongTimeWilltheTransmissionFailWhenIDo

[Lorrin Barth]

Well this is just my opinion of an opinion but I say if a fluid change is going to kill a transmission it was near dead anyway. So, not much of a risk.

[Gary]

Here is how I determine what to do. If the transmission fluid has always been changed at regular intervals and the fluid is cherry than I would change it and the filter without question. If the fluid is dark brown or black then quite likely the transmission is already on its way out. The fluid will have clutch material in it in this case and that clutch material may actually be acting as a friction agent and the transmission will be used to running with that material suspended in the fluid which makes the fluid denser. If you remove this fluid you may speed up the demise of the transmission because it may start slipping due to loss of friction and slipping generates heat. DO NOT let anyone flush the transmission with a machine. Those flushing machines can do more harm than good, in fact my shop put all the tranny flush machines in the shed because they are a liability. They can actually move metallic particles into places where they shouldn’t be and clog up orifices in the tranny potentially if the fluid is old enough. If the fluid in yer vehicles ain’t burnt or black I would personally just do a pan drop and fill +a filter. Just my .02

[Stephen Bowen]

The other wild card is all about the build up of “Varnish”. Old fluid that is brown or really deep in color normally puts a varnish type build up on parts and such. At times the only thing holding pressure in servos and what not? Is the varnish build up.

New transmission oil also contains detergent to keep parts clean. And yes when it gets older and ‘brown’ (aka, burnt up) the detergent has long sense failed/become weak.

Introducing fresh fluid with full strength detergents like it came out from the factory? Will remove that varnish build up–and the result can be leaky seals and slippage.

Despite what car makers will state? There is NO such thing as a life time fluid in any part/assembly. Many makers state that..and it’s bunk. Kinda like a fuel filter. The larger can type is supposed to last the lifetime of a car/truck. And it works good for several years–true. But when it bungs up? It’s long past your warranty.

Normally I suggest fluid be changed out every 40k to 50k. (or every 3 years) That’s just me. Others do things differently, and that’s okay. Going around the 80-90k mark? I would inspect the fluid first. Is it still pink and doesn’t smell burnt up? If so? Then a filter/fluid change may not hurt, it should help prolong the life. (I state “MAY” because anything is possible…and I’m not going to be on the hook for a transmission rebuild)

If the fluid is brown/black and smells like a sweat sock thats been passed around a skunk smell factory? Then it’s a crap shoot…..Might help…or it might kill it.

S-

[EricTheCarGuy]

I’ve written extensively on this question here.

http://www.ericthecarguy.com/faq/solving-transmission-problems

Keep us posted on your progress.

[Bill]

I must be the luckiest S.O.B in the world cuz I do transmission flushes with a exchange machine almost every day and have yet to have a problem. I road test em first and if the trans works as intended I flush em with B.G. cleaner, synthetic universal fluid and add the B.G additive.

Don’t care if it’s Honda, Toyota, Ford, Chrysler or a Smart car and it’s brown, black, pink or all three.

In fact, most times they shift better after. Besides, if I don’t do the job they will hire someone who will.

If I notice a problem on a road test I leave it up the the management and the customer.

[Jeremy Myers]

I think alot of people get the terms “purge” and “flush” confused when it comes to transmissions. Hooking up a purge machine that is simply replacing fluid as its draining out the old does not hurt the transmission at all. The high power flush machines that blow crap around inside your transmission is the ones that are harmful.

[Author]

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