I had trouble figuring out the washer thing for changing fluids. It looks like there are 3 different kinds on an RX. The fiber one for oil changes. A flat washer for the transmission pan and the front differential/trans-axle. And a crush washer for the transfer case drain/fill and rear differential drain/fill.

When reading the old threads it seemed like people were interchanging the metal washers. I really don't consider the trans pan washer a "crush" washer. It will deform over time and should be regularly replaced. But it does not look like it is designed to "crush" like the other one. Anyway, I think this is how they should be used.


Part # 12157-10010 crush washer used on rear differential and transfer case for both drain and fill.

Part # 90430-18008 flat washer used on transmission pan and front differential/trans-axle.

Part # 90430-12031 fiber oil pan washer

 

I get the fiber ones from the dealer as well that comes when I buy the filter. On some cars they use a metal flat crush washer. My Honda and Acura cars were this way. It is possible that if you buy non OEM oil filters they may be just giving you universal metal crush washers. Either way, my only concern is not to over torque the drain bolt and accidently cause it to strip, and that it doesn't leak when torqued to spec.

 

I never re-use the washer. Been doing oil on 3 Lexus (GS4, sc4, and Rx300) and have never come across the the fiber washer. Proportionately it has been the middle washer in the picture above.



Am I correct that irrespective of washer type (nylon, fabric, copper, aluminum, alloy) as long as you do not exceed the specified torque you will never strip the threads [getting a good seal is a different matter].

Salim

 

I saw a whole line of washers at AutoZone yesterday.

As I alluded to before, I haven't been using washers at all and have had no thread issues (and I change things a lot).

 

That fiber like one may be a new thing. Not sure when Lexus started using it. My old SC400 used the metal one that most of you use. Only when I got my 04 RX330 did I start seeing that fiber one. On my last oil change on the LS400 I bought early this year I bought the filter and washer and it too came with that fiber one. So, either one I think you are okay.

PS. I've always used a torque wrench to torque to spec, and I have never stripped the pan or had a leak from the bolt. A few Toyota mechanics I know have had to change out or retap oil pans before due to stripped pans via over torquing. Good mechanics can go by feel and know when too much is too much because they do it so often they know what they are feeling, but all it takes is that one "Too" much and your treads are shot.

 

First time I did trans drain and fill I re-used factory washer and had a slight drip. Ever since I used new washer (90430-18008) on both trans pan and front diff and haven't had any problems.