[LaceGrace]

I have a 2015 Hyundai Sonata with 33,000 miles. The transmission fluid has never been changed. Some websites say to replace the fluid at 60,000 miles. My question is does the transmission fluid degrade over time regardless of miles, necessitating I change it now, or can I wait until 60,000 miles; which will take approximately 2 more years considering my current driving?

Any advice would be greatly appreciated.

Thank you very much!

 

[Turbonut]

Wait, it will be fine.

 

[cj133]

I assume this is an automatic?
I always went by what it looked and smelled like on the dip stick, though I'm sure some will say that's not good enough.

If it was nice and red and not burnt I left it alone regardless of age or mileage. I've had automatics with 200,000 on the fluid and I've had a 2006 Honda 5 speed with fluid I had to change every 30K, but that was a unique case.

Assuming the transmission has a dip stick or a way to inspect the fluid, that is....

 

[missingcurlybracket]

I assume this is an automatic?
I always went by what it looked and smelled like on the dip stick, though I'm sure some will say that's not good enough.

If it was nice and red and not burnt I left it alone regardless of age or mileage. I've had automatics with 200,000 on the fluid and I've had a 2006 Honda 5 speed with fluid I had to change every 30K, but that was a unique case.

Assuming the transmission has a dip stick or a way to inspect the fluid, that is....

Yep I think the Sonata dropped the manual in 2013.

And nope, no dipstick, by the time you get to the fluid, you might as well change it while you're at it.

I'd wait until 50-60k before thinking about it personally.

 

[flemmons]

The 6spd auto in the Sonata is pretty much rock solid. 60K is nothing for that transmission, and since there are no combustion byproducts (like in engine oil) you should be fine. That transmission is warranted for 10yrs/100K miles to the original owner and if you have only done 33K miles you haven't really put any wear and tear on it. That being said, if you are planning on keeping the car as long as possible, I would suggest a drain and refill, not flush at 10yrs or 60K miles, whichever comes first.

Unless you are drag racing it or pulling a trailer.

 

[cj133]

The 6spd auto in the Sonata is pretty much rock solid. 60K is nothing for that transmission, and since there are no combustion byproducts (like in engine oil) you should be fine. That transmission is warranted for 10yrs/100K miles to the original owner and if you have only done 33K miles you haven't really put any wear and tear on it. That being said, if you are planning on keeping the car as long as possible, I would suggest a drain and refill, not flush at 10yrs or 60K miles, whichever comes first.

Unless you are drag racing it or pulling a trailer.

Thats how I do it but the down side is assuming it has a torque converter and it doesn't have a way to drain it you have to do many drain and refills to get most of it changed.

 

[Hanular]

Thank you all so much for the advice. The transmission is automatic. Sounds like I can wait until at least 60,000 miles before any fluid change regardless of fluid age. All the input is much appreciated!

 

[flemmons]

Thats how I do it but the down side is assuming it has a torque converter and it doesn't have a way to drain it you have to do many drain and refills to get most of it changed.

Dealer told me that on this specific transmission to never do a flush if there are no issues. That recommendation was based on several transmissions that developed issues after doing the complete flush and the chemicals it involved. After those issues, they no longer recommend anything but a drain and refill. At 65K miles, the fluid drained from my transmission looked almost exactly like what was going back in. Drove the car another 10K miles before selling it and had zero issues.

 

[AndreyVG]

Any oil ages and oxidizes when operating at high temperatures and critical loads. On this transmission, there is no way to change the filter during an oil change. If the ride is smooth, the fluid in this transmission needs to be changed every 30,000-40,000 miles. If you like to start from a traffic light on a kick-down, then you need to change the fluid after 20,000 miles. Any mechanical engineer will tell you that.

 

[cj133]

Any oil ages and oxidizes when operating at high temperatures and critical loads. On this transmission, there is no way to change the filter during an oil change. If the ride is smooth, the fluid in this transmission needs to be changed every 30,000-40,000 miles. If you like to start from a traffic light on a kick-down, then you need to change the fluid after 20,000 miles. Any mechanical engineer will tell you that.

Interesting..

Oxidation is apparently a big reason they removed dipsticks as they introduce oxygen into the system

 

[AndreyVG]

Interesting..

Oxidation is apparently a big reason they removed dipsticks as they introduce oxygen into the system

Transmission housing with free breathing. The dipstick was taken away so the owner would not see the black goo by 50,000 miles. If you don't change the oil, the transmission will run 100,000 miles and die. It's designed for this. If you change the oil on time, then 200,000 - 250,000 miles without problems.

 

[DarrenBach]

Transmission housing with free breathing. The dipstick was taken away so the owner would not see the black goo by 50,000 miles. If you don't change the oil, the transmission will run 100,000 miles and die. It's designed for this. If you change the oil on time, then 200,000 - 250,000 miles without problems.

If you're the "expert", why do you call it oil? Yes, it does vent and the dipsticks did have a good seal built-in.

 

[AndreyVG]

Liquid synthesized from gas, are you talking about this? Well, it also performs the function of creating a film on the contact patch of surfaces.

 

[Johns2.0T]

I like doing my ATF drane & fills at around the (60-65,000 Km's Canadian K's) or 37.000 usa miles.
might be early for some people but when you factor in idle time stop & go traffic that fluid is actually more beaten up then many like to beleive heat is what kills an Automatic transmission changing ATF along with useing the correct fluid spec fluid will prolong its lifespan.

 

[cj133]

Transmission housing with free breathing. The dipstick was taken away so the owner would not see the black goo by 50,000 miles. If you don't change the oil, the transmission will run 100,000 miles and die. It's designed for this. If you change the oil on time, then 200,000 - 250,000 miles without problems.

That breather is a little more complex than you think.


I thought you were a mechanical engineer? What field do you work in?

With all due respect if you have black goo at 50k the trans is already shot.

 

[flemmons]

If you are finding "black goo" in your transmission fluid at 30K, 60K, even 90K, you have much bigger issues than oil change interval.

 

[AndreyVG]

If you are finding "black goo" in your transmission fluid at 30K, 60K, even 90K, you have much bigger issues than oil change interval.

It depends on how you use the car. When I was 25 years younger, I changed the transmission fluid every 10 thousand km. BMW M5))

 

[AndreyVG]

That breather is a little more complex than you think.


I thought you were a mechanical engineer? What field do you work in?

With all due respect if you have black goo at 50k the trans is already shot.

Electromechanic. Mainly non-destructive testing and diagnostics of the state of electrical equipment with voltages above 200 kV.
The rate of fluid degradation is directly related to the dynamics of your driving style.

 

[cj133]

Electromechanic. Mainly non-destructive testing and diagnostics of the state of electrical equipment with voltages above 200 kV.
The rate of fluid degradation is directly related to the dynamics of your driving style.

So your work has nothing to do with automatic transmissions or hydraulics in general? Just curious. Although it does sound like something I'd like to hear about in PM honestly....


The fluid degradation has to do with a lot more than just driving style. In fact id argue that aggressive driving could result in longer life especially with modern transmissions due to less converter slippage and stronger clutch engagement (firmer shifts). Running a torque converter below its stall speed makes a lot of heat as does slipping clutches for a smooth shift.

It also has a lot to do with the design of the transmission. My dad had a modified TH400 with well over 200k on it's fluid and it was still bright red. I had a TH2004R with 140k on the fluid and it was alright... Not great but alright.

The Honda 5 speed I had was very hard on the fluid and it was pretty bad when we bought the vehicle at 60k. That should've been changed every 30k.

My overall opinion is the removal of dipsticks has more to do with keeping oxygen out of the system than anything. And if your transmission has no way to check the fluid then follow your owner's manual on changing it.

 

[Turbonut]

Any oil ages and oxidizes when operating at high temperatures and critical loads. On this transmission, there is no way to change the filter during an oil change. If the ride is smooth, the fluid in this transmission needs to be changed every 30,000-40,000 miles. If you like to start from a traffic light on a kick-down, then you need to change the fluid after 20,000 miles. Any mechanical engineer will tell you that.

That's ridiculous.
Well, mechanical engineers designed the transmission and fluid, and also are responsible
for the recommendation of the specific service intervals, lifetime.

In fact, the old '08 Optima 2.4 I sold a few years ago had 298,000 miles and no fluid change
at all, no problem.