Trans Fluid Change

Today I changed my trans fluid on my 2007 Prius. The Toyota service history said "transaxle fluid service" or something to that effect around 50,000 miles at the dealer, 2-3 years ago. I now have 81,000 miles, bought it with 54,500 on it.

Judging by the way the allen head drain plug looked, it had never been removed. And it was so tight it took myself and a helper to get it to break loose!! And Im no wimp - I have popeye arms and a breaker bar, lol. The fill plug looked the same way (never touched) but was much easier to break loose.

The fluid that came out was not really dark at all, was probably very slightly darker than new stuff. So I almost wonder if it did get changed at 50k miles after all but maybe the dealer used another method to drain/refill it? My drain plug had just the slightest amount of build up on the magnet. It was so slight I almost thought there was nothing until I wiped it with a rag.

Three questions:
- Would a dealer use a suction device, or any other method to drain/refill the Prius transaxle? (that would explain the drain and fill plug that both look like a socket/bit never touched them)

- Has anybody experienced an increase in mpg's after changing the cvt fluid? I drove it ~100 miles after, and my avg. mileage went up 1.5mpg's I already had 120 miles on that tank, and today is colder than it has been. So I was really expecting a decrease.

- I put it almost 4 quarts. I have maybe a 1-2 ounces left out of the 4th quart. Normal? I read on the site, people have recommended only putting 3.5qts back in.

 

Heres what I did:

I put the front end on ramps. The rear was still on the ground. I did this at first to prevent opening the fill plug and having fluid come out and making a mess.

After I removed the fill plug, I then loosened the drain plug. THEN I went and jacked the rear end up. I jacked the rear end up higher than the front at that point. Then I went back and removed the transmission drain plug. I let the car drain like this, with the rear end slightly higher than the front for about an hour.

I then lowered the rear end so the car was completely level. I added transmission fluid through a funnel and piece of clear tubing until I got to 3.75 quarts. I removed the hose - nothing dribbled out at that point. I did this 2 more times until I added most of the 4th quart. Finally, I was down to the bottom of the 4th quart, there might be 1/4 of an inch of fluid left at the bottom of the container. I figure I added almost all of the 4th quart until it started to dribble out.

I then lowered the rear again, installed the fill plug, torqued everything to specs and went for a test drive

 

Well, the front was on ramps. I was under the front when I was loosening/tightening the plugs. Other than that, the rear was supported by a jack only. So if the rear fell, it doesnt really matter to me because Im not under the rear of the car

And I dont mind raising and lowering the car a bunch of times - keeps the neighbors on their toes wondering if Im really crazy or not!! haha

 

Well, judging by the engine oil drain plug for example - you can tell a socket has been placed over the plug - you can see wear associated with two pieces of metal sliding over each other.
After I removed the transmission drain plug, you can look at it and clearly tell it had been tampered with at some point now. However, before I touched it I carefully examined it by eye and it looked like it had never been touched. But hey, Im no metal forensic specialist or anything, and apparently I was wrong because it does appear the fluid was changed at one point, based on the condition of the fluid and the very little accumulation on the magnetic drain plug. I was just trying to hone up on my detective work and catch the dealership not doing something they billed the last owner for, thats all

And as far as the mpg increase, I must be experiencing some kind of placebo effect - Im cool with that!

 

Thanks for all the feedback. I now know that the dealership did in fact service the transaxle and that just looking at the plugs arent a solid indicator of being previously tampered with.

In the meantime, I am happy that changing the trans fluid is so easy. I dreaded the days when I would have to put my SUV up on ramps, chock the rear wheels, get under it and drop the transmission pan (but first removing 15 small bolts). I finally got it down to an art towards the end, I would siphon out the trans fluid through the dipstick tube with my mity-vac, and then drop the pan - little to no mess that way. In any event, my arms and hands would all be cramped and tired after from working laying on my back with my hands above my head trying to thread back in 15 small bolts.

The Prius was very straightforward Ill change the fluid again in 30k miles or so, cheap insurance IMO.