Transaxle oil study report

Jun 04, 2011 6 Replies

I've been conducting a Prius transaxle oil study over the past six years and just posted a summary report:



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"Early transaxle oil change - a new car should have the transaxle oil changed early with the first engine oil change. This will flush the early wear material and loss sealant bits.



NHW11 - should use Type T-IV over Type WS as the wear patterns suggest the lower viscosity losses may be more than offset by higher wear, friction losses. NEVER USE AMSOIL ATF DUE TO EXCESSIVE COPPER WEAR. Do an early change and then every 30k miles.



NHW20 transaxle oil should be changed early, at 60k miles, and then



90k miles thereafter.

Use of a transaxle heater to bring the oil closer to operating temperature should receive equal weight to an engine block heater in colder weather."



Bob Wilson


I have a 1994 Camry that never had the transaxle oil changed and it's still working. Is there a concern in the future?

Undoubtedly already a concern, at your dealer or service shop...

I had a 1991 Camry before an accident led to it having the title pulled by the insurance company. It was a solid, 32 MPG car and I would still be driving it but for the accident. But once I lost it, the replacement was our 2003 Prius.

Our 2003 Prius gets 52 MPG, dawn-to-dawn and like the famous heroic pig with the wooden leg, You don't want eat him up at one time:

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We have to use our 2003 Prius but we don't want to use it up too early.

Bob Wilson

If you had the transmission fluid changed, there is some exchange between it and the transaxle/differential, through a baffle.

Thank you all for the info. I will get at least transmission fluid replaced. I assume it's easier to change that than transaxle.

If this is the first time you've had it changed, *do not* allow them to do a "power flush" or "fluid exchange." These will force crud into places it should not go, and can cause failure of the transmission. Instead, have then do a 'spill and fill' fluid change, which is just a regular oil pan drain and fill change, but have them remove the pan and replace the fluid filter screen and wipe the pan clean. Then have just the fluid change (not the filter replacement) done again every thousand or two miles until it's been done about three times. This is the safest way to replace ancient transmission fluid in old automatic transmissions. The transmission used in your Camry is tough, but the brake bands have a soft compound that gets into the fluid, so regular fluid changes really extend the life.

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