Trans fluid change, yes or no

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MistaEnduro

MistaEnduro

Joined
Sep 30, 2025
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Location
Grand Junction, Colorado
I have a 08 lx with just south of 270k miles on it. I was hoping to change out all the fluids on it soon (transfer case, diffs, trans, etc.). I have heard mixed opinions from shops on doing a drain-and-fill on the trans. Some say it’s fine, some say don’t even go near it.

I have no idea if it’s ever been changed out. If someone with more experience than me would love to share some wisdom if I should change it out or not, I would be appreciative!
 
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There are a few strategies to consider:

1.) Do nothing. "it ain't broke, don't fix it". "It's lifetime fluid"
2.) Complete drain and fill. Total replacement of the transmission fluid.
3.) Drain and fill what comes out of the pan (about 4 quarts) every engine oil-change interval or two.

I have used 2 and 3 on different vehicles. I prefer 3. Particularly if the vehicle has really high mileage. I think the strategy is that you'll still have friction material in the old fluid, but introducing new fluid incrementally might avoid "shocking the system" with smooth clean fluid, if the transmission has worn friction discs.
 
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Hey man, this has been debated to death in this forum.
@CanadianRockyCruiser gave you the options. If you are looking for a consensus which one, you'll not find it in this forum.
Save your time and pick whichever you like or feel comfortable doing it. There is no clear data (available to us) to support one is better than the other.
A logical person would agree that no fluid is forever. But what is "too long" has not been defined yet.
 
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CanadianRockyCruiser said:
There are a few strategies to consider:

1.) Do nothing. "it ain't broke, don't fix it". "It's lifetime fluid"
2.) Complete drain and fill. Total replacement of the transmission fluid.
3.) Drain and fill what comes out of the pan (about 4 quarts) every engine oil-change interval or two.

I have used 2 and 3 on different vehicles. I prefer 3. Particularly if the vehicle has really high mileage. I think the strategy is that you'll still have friction material in the old fluid, but introducing new fluid incrementally might avoid "shocking the system" with smooth clean fluid, if the transmission has worn friction discs.
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I’ve thought about doing #3, currently I’ve only had to do one change and I did the drain-fill-start and shift gears-drain and repeat.

What does your fluid look like with #3 and are you just replacing the exact amount that you drained or are you doing the official fluid level check at the specific temp?
 
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Artie said:
I’ve thought about doing #3, currently I’ve only had to do one change and I did the drain-fill-start and shift gears-drain and repeat.

What does your fluid look like with #3 and are you just replacing the exact amount that you drained or are you doing the official fluid level check at the specific temp?
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How about this...
#4 Periodically drain what comes out after removing the drain plug and tube, approx. 3 qts IIRC, and replacing exactly that amount along with the shift gears step.

I think this is what I'll do for the first change as I'm confident the transmission is properly filled. Maybe later on do the whole multi-change with temperature adjustment.

Still undecided.:cool:
 
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I would do several drain and fills if I were in your shoes. I wouldn't do them just at oil change intervals, that would take too long. I'd do it every weekend for like six weeks. Total PITA, but if you're doing it yourself you'll get used to it. I think doing it all at once sounds too risky, as does ignoring it. I would also switch to Valvoline MaxLife ATF, which is full synthetic. That's just my opinion. Good luck!
 
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FrazzledHunter said:
How about this...
#4 Periodically drain what comes out after removing the drain plug and tube, approx. 3 qts IIRC, and replacing exactly that amount along with the shift gears step.

I think this is what I'll do for the first change as I'm confident the transmission is properly filled. Maybe later on do the whole multi-change with temperature adjustment.

Still undecided.:cool:
Click to expand...
That’s pretty much what #3 is. Just replace whatever comes out… idk if running to temp and shifting gears makes a difference for this #3. Draining while cold and refilling that amount is what I’m thinking.

I like this option just to avoid the hassle of checking the level. If you’re doing this method then the difficulty becomes removing the panel that is over the fill plug, it’s not bad if you have a shallow socket or a long enough ratcheting wrench. Since you and I both tow I feel like this is a good option every other oil change. It gives us a chance to visually inspect the fluid and do more if it looks necessary. If you can keep those converter temps down it may be overkill but I don’t believe you will run into problems over maintaining this component. I did have one impressive temp on this current fluid rotation, 217° pan and 280° on the converter. It’s still shy of the temp light triggering but enough to make me think the #3 option is the move for me.
 
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I appreciate the wisdom haha, I think my plan is to do 3 ish drain and fill's over a couple weekends. The mileage is just getting so high that im getting a little nervous about proper service intervals.

Thanks!
 
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Artie said:
That’s pretty much what #3 is. Just replace whatever comes out… idk if running to temp and shifting gears makes a difference for this #3. Draining while cold and refilling that amount is what I’m thinking.

I like this option just to avoid the hassle of checking the level. If you’re doing this method then the difficulty becomes removing the panel that is over the fill plug, it’s not bad if you have a shallow socket or a long enough ratcheting wrench. Since you and I both tow I feel like this is a good option every other oil change. It gives us a chance to visually inspect the fluid and do more if it looks necessary. If you can keep those converter temps down it may be overkill but I don’t believe you will run into problems over maintaining this component. I did have one impressive temp on this current fluid rotation, 217° pan and 280° on the converter. It’s still shy of the temp light triggering but enough to make me think the #3 option is the move for me.
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We are thinking alike.
I hit a few high temps West of Denver this past summer but I was watching so I saw it and backed off.
One clue I had as to how hard I worked mah baby was a bit of sludge in the oil cup when we got home.

To do this, I'm afraid I might have to buy a new long ratcheting wrench, maybe one that swivels. :clap:
Maybe even more than one.
Ya can't have too many tools, ya know.
Filling: I was planning on running a tube up to a hanging funnel.

I'm gonna order the parts (O rings, spare fill & drain bolts in case I eff them up) this week.

I'd pay someone to do this but I'm so jaded from horror stories heard here and elsewhere in addition to my own experience that at this point I'm reluctant to have anyone add to the wiper fluid.
 
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I regularly drain and fill my 200 (almost 60k miles) and my 100 (300k+ miles). I measure what comes out with a graduated container and put the same amount back in rather than going through the trouble of following the FSM procedure for the 200.

I will say this, I did a complete power steering fluid flush on my 200 recently at about 55k and the fluid did not look great and that is the same ATF fluid that is in our transmission. Thus I am skeptical that it is a lifetime fluid and prefer to refresh it when I have the time.
 
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FrazzledHunter said:
We are thinking alike.
I hit a few high temps West of Denver this past summer but I was watching so I saw it and backed off.
One clue I had as to how hard I worked mah baby was a bit of sludge in the oil cup when we got home.

To do this, I'm afraid I might have to buy a new long ratcheting wrench, maybe one that swivels. :clap:
Maybe even more than one.
Ya can't have too many tools, ya know.
Filling: I was planning on running a tube up to a hanging funnel.

I'm gonna order the parts (O rings, spare fill & drain bolts in case I eff them up) this week.

I'd pay someone to do this but I'm so jaded from horror stories heard here and elsewhere in addition to my own experience that at this point I'm reluctant to have anyone add to the wiper fluid.
Click to expand...
It’s an easy process but daunting your first time.

This video is a great breakdown on it.

This is the graduated pitcher I use.

Hanging the funnel from the hood with a tube in the fill spot is the move. It’s too tight to get a transfer pump in there and with the pitcher you can just pour the entire amour in there slowly and be done with it.
 
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I was in the same boat. I have 233K miles on a vehicle that I had no idea of the service history. Starting at 220K miles I did a drain and fill. Oil looked like crap. Dark brown but not burnt and certainly didn't have the same viscosity characteristics of new oil. Since then, I've done two additional drain and fills. Each time the oil looked a little improved but still brown with a hint of red.

Since I haven't experienced any adverse effects from the three drain and fills, I'm getting ready to just do a full fluid swap with a pan drop to change out the filter. At this mileage, I prefer to know the filter is in good shape and the pan I free of particulates.

Good luck.
 
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solution to pollution is dilution.

At minimum do a drain and fill and check the levels to insure its proper. Idemitsu is a good alternative to OEM WS Fluid.
 
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