If my differential fluid has never been replaced, should I consider replacing it? ‘01 RX with 160k+ miles

 

My Lexus Maintenance Manual says the differential fluid should be changed every 15,000 miles...which I think is ridiculous. My own schedule is about every 50K. My mileage is about the same as yours. One thing for sure, the heavy lubricants available today have to be superior to the ones that came out of the factory 20 years ago, IMHO. If you do decide to do the job, just make SURE you can loosen the fill plug before doing the drain!

 

Ricco is absolutely right. There are great tutorials on this forum about changing the front and rear diff fluid. It's a little messy and it takes some time, but it's not hard. Good luck!