2010 Nissan Versa Hatchback w/CVT, original owner, 117k miles, fluid never changed (my bad), not slipping and runs OK, overall car is in good shape. Currently driven about 5k miles per year.
Should I change the fluid now and regularly thereafter, leave it alone and cross my fingers OR sell the car before it dies?
Should I change the fluid now
Yes!
But with a CVT, that friction material just causes problems
Only conventional automatics shed friction material, because it comes from the "friction discs" in the clutches, which CVTs do not have. Friction material looks like brake pad dust. It's dull and black and looks like black or dark grey mud.
CVT fluid should be changed often for two reasons. The core of the CVT is the steel belt that runs over two cone shaped drums which change shape to 'vary' the drive ratio. The belt has "elements" that allow it to change radius and grab the drums, and the elements all rub and wear on each other, the drums, and the belts, and get very hot. This heat wears out the fluid. Think of oily food getting baked onto your bakeware. It turns into varnish. This wear also produces very fine metal shavings. Obviously, metal shaving aren't good. You're basically making a polishing paste that wears down metal. I haven't yet seen dirty CVT fluid in person, but steel shaving usually look like glitter.
https://www.youtube.com/watch?v=c47caRqbbnE
and as I post this looking at the video , I realise that CVTs may in fact have clutches to engage reverse so I have to eat a bit of crow. But as you can imagine, reverse doesn't get used very often, so clutch material shedding is nearly as significant an issue as it is in a conventional automatic with clutches between every gear (on a modern 10 speed that's a lot of clutches!)
Yes! That’s the correct explication. I wasn’t familiar with what to call the material coming from the wear of the belts and cones.
Pretty different. In a clutch you want to CREATE some friction. In a CVT you want to minimize it. The 'dirt' is different things in each one.
See if I got this right here. The belt debris from a CVT contains other 'elements' along with the metal filings you can see. All that junk is suspended in the fluid until a service.
Does this mean the friction multiplier of this fluid likely increases more rapidly than compared to traditional automatic, hence 'not as durable as traditional automatic'?
I am of the understanding that it ok to change transmission oil for a manual and CVT at any time.
But for an automatic, once it reaches higher mileage, it is probably better to keep the old fluid as is.
@kaizen is the premise a CVT is more similar to a standard transmission than an automatic?
I think the assumption the CVT is more like an automatic transmission than a manual. But it is its own thing entirely. There is one way which it is different, from what I understand.
Both a CVT and an automatic will wear over time. That wear has nowhere to go but the transmission fluid, so it builds up in the transmission fluid, as suspended friction material.
In an automatic transmission that friction material may actually help the transmission work properly (if the fluid has never been changed).
But with a CVT, that friction material just causes problems for a CVT. Which is why changing out the CVT fluid more frequently may help prolong the life of a CVT.
Really nice explanation @Kaizen . Thanks, your explanation should be in the FAQs, it's really that good.
Does this mean the friction multiplier of this fluid likely increases
friction multiplier?
Like I said, the fluid in the CVT wears out quicker from heat and oxidation (basically breaking up the oil molecules and turning them into non-oily things that gum up and don't lubricate)
And gets dirty. Dirt = bad.
@mmj meant friction material. These contaminates, friction or clutch materials, accumulate in the different transmissions. The CVT transmission is simply more susceptible to wear at an earlier time.
@Hixster.
Contaminates in a conventional automatic is mostly the clutch/friction material, because they use clutches A LOT. Every time it shifts gears. And a tiny bit of metal.
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Since a CVT doesn't shift gears (except for reverse) it does not have clutches, and therefore doesn't shed friction/clutch material. The contaminates are mostly metal from the belt and drums.
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Yes, CVTs are pretty crude devices. Lots of metal on metal rubbing happening. They wear out quite quickly, especially when not maintained.
Check the FAQs under 'Maintenance" as this question is asked a lot. Check out the second video in particular.
Serious consideration should be given to doing anything to a Jatco transmission with high mileage.
CVTs don't have clutches. high mileage is not an issue.
Mr. Wizard's video is a 'sticky'. He emphatically states about 8:25 "do not change if you've gone 100k"? Just confused as I agree with him.
No, he doesn't.
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Watch again, put the speed on slow, and listen carefully because he speaks in broken sentences.
"the idea that you can go 100k miles without changing the fluid .... you will destroy the transmission"
Yes, that's absolutely true.
At no point does he say "do not change the fluid after 100k"
Whew! Thanks @mmj At half speed it's very clear he's referring to the 'lifetime fluid myth'. He's saying to service the CVT, ignore the naysayers.
exactly