Transmission drain/flush, how often.

You make some good points and makes sense to me.

Yes, oil is the easy one, thankfully. Here I don't think even the Toyota dealerships use Toyota oil - Mobil or Castrol, I think.

Thanks for your input.

 

When I asked the Toyota dealership about the service, they told me that the fluid was good for the life of the vehicle and didn't need to be changed (even at my high milage). I came across this video during my internet research. I just had my transmission fluid changed at 166,000 for the first time by Dynamic Garage in Libertytown, MD. Total cost $115.00 and my Prius drives much smoother.

 

And if this has been mentioned earlier I would like to reinforce........that a "flush" is NOT necessary and often causes more problems than it solves. Extra Dealer Profit is about the only reason for doing it.

 

After watching the above video on how to change the tranny fluid, I am perplexed by the mechanics statement that the clutch material in the old fluid was making the fluid dark. I didn't Know there were clutches in a cvt tranny. I thought the Prius had planetary gears.

 

There is a clutch of sorts, but it is always clamped down and should never slip unless there is catastrophic failure.

(about 5:20)

 

I saw it on the Internet; it MUST be true !!!

 

There is one reason for a flush: if the wrong stuff has been put in.

And all a flush need entail is: drain and refill, multiple times, with a short drive after each refill.

 

I believe it's called a "torque-limiter." I've seen them on larger machines when they're ripped apart. They're designed to relieve stress on the drive-train which may be due to abrupt shifting or other sudden changes in drive-line velocity. In a practical sense, the Prius engine remains directly connected to the wheels at all times. Motor-generator 1 (MG1) compensates for the gas engine when it's stopped or running at a speed not proportional to the drive-train, and by running in reverse when the gas engine is stopped, while the car is moving.

Those YouTube videos by John Kelly from Weber State explaining the Prius drive-line are really excellent. BTW, he drives a Chevy Volt himself.

 

As you mentioned it wouldn't be clutch material making the fluid dark, it would be actual degradation of the fluid itself (and perhaps a very, very small amount of particulate from planetary wear). There are no active clutches either as noted above, it's a torque limiter (like a manual clutch that remains engaged at all times) and absorbs any torque spikes seen in the drivetrain.

 

In the case of the Prius, it could be caused by a short in the windings of the electric motor-generators. In a different video, the transmission had failed because the insulation had burned off the stator.

 

I've seen that before and it's not entirely clear what caused the MG2 shorting issue in the transmission, but I think that's part of the reason why sticking with the OEM fluid and changing it often could prove helpful.

 

That makes good sense. There's no telling how the varnish on the stator windings might react to detergents in the oil.

 

Whenever somebody says that you "have to use this oil" or "any non-OEM product will harm the vehicle" I'm always very skeptical.
After all.....ATF, gear and engine lube are hardly what you would call emerging technology.

However (comma!!!)
I believe I would go with the herd on this one!
I'm mechanically competent enough to change the transaxle fluid.
I don't want to HAVE to find out whether or not I'm mechanically competent enough to do a transaxlectomy on a Prius.

I believe that I would go with a change at 60K and see what happens after that.
You're looking at perhaps $50 in fluid (or less!) and an hour's labor.

If I ever buy a new G3.....maybe I'll do it sooner than 60K but the stator windings have me convinced enough not to try to use a substitution for the OEM fluid.

Good discussion!

 

I'm acquainted with inferior lubricants. The salesmen will give you any guarantee you want, but when your seals all turn to sludge, you're on your own. Happened to a farmer I know.
Just like that.

 

Did my third trans fluid change last weekend. 30,000 miles on this fluid with vehicle total at 70,000 miles. Fluid still red and no metal whatsoever on the magnetic plug. Just a tiny film. So Redline D6 showing no wear at all so won't bother with a UOA at this time. Next change will be in 50,000 miles at 120K vehicle total.

Changed out the fluid at 5,000 on it from new and that showed the most wear I have seen. Moved over to Redline D6 at that time. The first 5-10,000 miles are where all the wear happens in this cvt. I would say change the fluid out on a new Prius at that time and your good to go for at least 125K. Lot of initial break in wear.

7 years on Redline D6.

Also changed out the Inverter fluid at that time. Your already under there so pull that bolt. So easy to change the Inverter coolant its so simple.
Also dumped just the rad engine coolant. I do that once a year. It helps. A full engine coolant change is very hard to get the air out and a total pia.

 

Fairly annoying, I agree

From now on I plan on replacing a gallon every 10 - 15k miles using the Lisle funnel so that no air enters the system. That will hopefully be a 5 minute painless exercise rather than the couple of hours the complete drain dance requires.

 

Me to. This car is very easy on the Engine coolant but I figure the cleaner it is the longer the water pump will last.