Accidentally put about half a quart of motor oil in the transmission fluid dipstick?

ALL4FUN777

MEMBER
2002 LEXUS ES 300
AUTOMATIC
220,000 MILES

Yesterday, I was getting ready for a trip and wanted to top off fluids, I wasn't paying attention and was talking to a friend and accidentally put about half a quart of motor oil in the transmission fluid dipstick! I'm kicking myself but wondering how I messed up? And I would love an explanation of what could happened. It was not much but cancelled the trip and just drove it home I was going to drain the fluid today and refill, do I need to do a flush as well? Advice would be greatly appreciated. I still can't believe I did that.

5 Replies

ALL4FUN777

MEMBER
3 POSTS

After looking it take fully synthetic, I'm low on funds and after looking for the transmission filter there's two kinds. I already got the fluid and don't really want to have to completely flush it because that's more work. I'm not sure if it's a big deal or won't hurt much, can I get away with just changing fluid? Or is it a total flush important? Also, which of the two filters is more important? Change both? Can I get away with not changing either and just fluid? I really don't want to mess up this car as it's my only daily driver vehicle but at the same time don't feel like messing with it so honest opinion would be greatly appreciated. Thanks

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Sunday, February 18th, 2024 AT 3:58 PM

JACOBANDNICKOLAS

MECHANIC
109,874 POSTS

Hi,

Since you drive the vehicle after adding the wrong oil, you should flush the transmission because it is now mixed throughout the transmission. If you had drained it before driving, you would have gotten the new/incorrect fluid out of the transmission.

As far as filters, the same thing applies.

Let me know if you have other questions.

Take care,

Joe

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Sunday, February 18th, 2024 AT 7:02 PM

STEVE W.

MECHANIC
13,572 POSTS

Well, regular engine oil has additives in it that the transmission won't like because it can glaze the clutch plates. If it were mine, I would take it to a shop that does full power flushing and have them do a flush and filter change. That would remove more of the fluid than a standard drain and fill would and should keep the transmission happy. There is another question though, has the transmission been serviced regularly up to now? If not, then it might be a moot point to do the flush and instead do the spill and fill by removing the pan and changing that filter.

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Sunday, February 18th, 2024 AT 7:12 PM

ALL4FUN777

MEMBER
3 POSTS

Thanks for the replies, I appreciate it. Sorry for all the typos, using a cracked screen phone (was stolen few days ago). I'm honestly not sure it's a 02. I bought the vehicle about a year maybe a year and a half ago with about 170 on the odometer it seems like it's been pretty well maintained, but I can't tell you because I didn't own it at that point in time. I personally haven't done anything to the transmission yet, but like I said that's only been the past year and I do understand that I have driven it I only drove it for about 20 miles maybe just to get home. Then I got into another vehicle, I wouldn't continue to drive it, but I understand that's enough to already mix the fluid up. Do you have any idea what the cheapest I could get a flush at a shop for by chance? I got the fluid and filter it goes in the drain pan yesterday so I have both of those items today. I was going to go ahead and flush it myself. I was considering getting one of those cheap pumps from Harbor Freight and DYI. Is there really a big difference is it a certain kind of pump that they use at a shop that makes the large difference they can get more of it out is it that big of a deal I really don't have the funds to do that right now, but I guess if I needed to I could borrow it if it's that important. I appreciate the explanation breakdown of it. :)

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Monday, February 19th, 2024 AT 2:36 AM

STEVE W.

MECHANIC
13,572 POSTS

The difference with the shop systems is that you normally connect them in series with the cooler, then drop the pan and install a new filter then start the pump and then the vehicles engine. It pumps new fluid into the system and removes the old fluid into a recovery tank. Then you cycle the gears a couple times to get any fluid that may be in the valving. In the end you should have all new fluids and a new filter. You could rig up something similar with a hydraulic pump and such. But by the time you spend the money the shop likely could do it for less.