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I bought this vehicle last year. It was very well taken care of and I want to keep it that way. At a recent inspection, I was told that I needed the front and rear differential fluid changed and the automatic transmission fluid flushed. I set about to compare prices and actually found that the dealer had the best price for the transmission fluid flush and the diffs weren't too bad so I took it there. At three points I stressed "flush" not "drain and replace", but when I got my bill, the amount of fluid used (4 Litres = approx 4 quarts) looked more like a drain and replace than a flush. Maybe I am wrong. Can you please advise me. Also, my manual says that the transfer case fluid is due for a change, but the dealer said that this vehicle does not have a transfer case. What? Am I being treated like an idiot because I am female?

Answers from the Automotive Experts

Jessica Howe, Automotive Expert & Coach at AskPatty.com

Hello, 

Thank you for writing in, and great questions. First and foremost, if your RAV4 is not a 4x4, it will not have a transfer case. Transfer cases are responsible for sending horsepower to all 4 wheels when the vehicle is put into 4x4. Here's where you may have gotten confused. Most owner's manuals will include information for all related models, regardless if they are 4x2 or 4x4. It is possible and likely that your owner's manual has extra information that does not pertain to your exact vehicle. If your RAV4 is a 4x4, then it will have a transfer case and the technician was incorrect. 

The transmission drain and fill will require 3.7-quarts of automatic transmission fluid. This cleans out the fluid from the pan and transmission, but leaves fluid in the transmission lines and in the transmission fluid cooler if you have one. The transmission fluid cooler (similar to a radiator) is what will hold the most old transmission fluid given that you only get a drain and fill rather than a flush. If your vehile does not have a cooler, you likely have nothing to worry about when it comes to getting a "drain and fill" rather than a flush (which sucks the fluid out of the lines and the cooler). 

Here is where it gets even more complicated. A lot of technicians, including myself, believe that keeping a small amount of the old transmission fluid in the system actually has benefits over flushing all of the old transmission fluid. The most important aspects of transmission service include getting a new filter in the transmission, checking the inside of the transmission pan for signs of wear (dark fluid or metal shavings), and getting most of the transmisison fluid refreshed. The amount of tranny fluid left in the lines and the transmission cooler (if your vehicle has one) is small enough that it gets mixed in with the new fluid and processed by the new filter. During that process, the old fluid helps the transmission process the new fluid and after several minutes of driving will eventually get mixed together. As long as you replace the majority of the transmission fluid, you are doing exactly what that transmission needs to keep running. 

Transmisison fluid flushes that remove every bit of old transmisison fluid do have benefits and are the reasonable choice under a range of circumstances. That may include after a transmission is replaced, if the transmission fluid was fouled or contaminated, if the old transmission fluid was overheated, or other similar circumstances. Most automatic transmissions that have simply hit the recommended mileage for fluid replacements will be just fine with a fluid drain and fill. However, if you wanted and paid for a flush and didn't get it, that is reason to be concerned. 

Good luck, and good looking out. 


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