I’ve always wondered if changing transmission fluid too often could be a problem, especially with automatic transmissions. Is it just a myth or is there some truth to it?
I recently bought a used car with around 60k miles, and there’s no record of the CVT fluid being changed. I’m thinking of changing it, maybe even twice just to be safe. I don’t see how that could hurt, but I wanted to check with others here. What do you think?
Nope, fresh fluid is always better. Just like engine oil, all fluids break down over time.
Sable said:
Nope, fresh fluid is always better. Just like engine oil, all fluids break down over time.
And just like all oils, I also break down over time.
Sable said:
Nope, fresh fluid is always better. Just like engine oil, all fluids break down over time.
And just like all oils, I also break down over time.
I don’t need time to break down, but I do need time to recover.
If you’re doing a drain and refill, you only replace about 50% of the fluid the first time. For example, if the capacity is 12 quarts, you’ll only get about 6 quarts of new fluid in. You’d need to do it three times to get close to 100% new fluid.
I usually do two changes close together to get about 75% new fluid, then repeat every few years. The cost is the main downside, but if you drive in tough conditions, more frequent changes are better.
@JamesHenry
How much does it usually cost? I’m planning for my new ’25 Outback and want to budget for it.
Ethan said:
@JamesHenry
How much does it usually cost? I’m planning for my new ’25 Outback and want to budget for it.
I do it myself, so it’s just the cost of the fluid and my time. Right now, Amsoil CVT fluid is about $13.40 per quart, and it takes around 6 quarts per change.
@JamesHenry
I had 12 quarts and did two drain and refills. It helps to measure how much you take out so you know how much to put back in. That way, you can plan for another change if needed.
Just do it! Better to be safe than sorry.
I’ve heard you should avoid using Lucas in CVTs. If anyone has a different experience, let me know.
Luchivya said:
I’ve heard you should avoid using Lucas in CVTs. If anyone has a different experience, let me know.
This is one of those jobs where I’d stick with Subaru OEM fluid. It’s just safer.
@Clayton
That’s a good point. OEM is probably the way to go.
Change it 100%. Better to be proactive.
Definitely change it. You might want to do a couple of drain and fills back-to-back to get most of the old fluid out.
The differentials were done, but there’s no record of the CVT fluid being changed.
I think the myth about changing fluid causing transmission failure comes from people changing it after it’s already too late. The transmission was likely going to fail anyway, and the fluid change just happened to coincide with it.
You can change it as often as you want. It might slightly reduce wear on your transmission over time, but the difference might not be huge.
Fern said:
You can change it as often as you want. It might slightly reduce wear on your transmission over time, but the difference might not be huge.
Fern said:
You can change it as often as you want. It might slightly reduce wear on your transmission over time, but the difference might not be huge.
I wasn’t clear earlier. I meant that changing it multiple times a year probably won’t make a big difference compared to doing it once a year.
@Fern
Once a year? I thought most people recommend every 30k miles, which is about two years for the average driver.
Zain said:
@Fern
Once a year? I thought most people recommend every 30k miles, which is about two years for the average driver.
That’s probably fine for most people. My point is that you can’t really hurt anything by changing it more often. Different driving habits and cars have different needs. For example, I change my GR86 MT fluid twice a year because it sees a lot of track days. My Maverick has a less durable transmission, so I’ll change that fluid once a year.