ajay60610

Have a 2009 RX-350 AWD with 116,500 miles....manual stated that at 120,000 both the rear differential and transfer case should be "inspected"....not sure what that means...want work done at an independent mechanic's shop [not the dealer]...my question is should i get a "flush" or just refill both fluids if they are low...fluid needed is 1 qt.each Hypoid Gear Oil API -GL5...heard some bad stories that "flush" makes system worse, that it is better to leave both these fluids alone and especially NOT to do a "flush"...same with automatic trans. fluid[ drain and fill only]....need some help here ...thanks.

Lexuswiz

iTrader: (1)

With Lexus, they some how implemented a "lifetime" fluid for the drivetrain so you only need to top off if leaking (and fix the leak). But I call BS. I come from a lineage of Toyotas and I do transmission and gear box drain & fills regularly on all my cars, preferably around 30-40K miles intervals. I've noticed drain & fills improve shifting and in some cases reduce noise.

But very very rare do I see a drain & fill cause transmission failure. In those cases, the trans was probably already in bad shape before the fluid change. Right when I bought my RX330 I did a drain & fill of the trans with Valvoline Full Synthetic trans fluid and I noticed shifting improved in our crappy transmission.

ajay60610

Thanks.....i was trying to determine whether a "flush" of rear differential and transfer case was worth the money....need special machine i am told....not many independent shops have the machine but the dealer has one and charges accordingly [ for the flush service]..

cdnewton

Are you sure they are doing a flush on the differential and/or transfer case? Typically, those just drain/fill. We have an RX330 (not the RX350); however, I do the service every 30k. I will admit, I am bit obsessive with maintenance. If you are using a shop, how much are they charging for each?

As for transmission, if the shop is doing a fluid exchange (they use the power steering pump to pump through transmission fluid until it comes out looking like new fluid), I have found those to be safe. A flush, where they put through cleaner chemicals, I wouldn't sign up for. I am also not a believer 'lifetime fluids'; if you plan to keep the vehicle, in my opinion, a drain/fill of the transmission fluid (about 4 qts) will likely keep the transmission running a long time.

Lexuswiz

iTrader: (1)

Yes, worth the money if the service uses a machine. Otherwise a drain and fill can be done in your garage. There is a specific machine but it's no way special, just a fluid exchanger. My Lexus dealer will not touch the trans or diff but Toyota will and they have the fluid exchanger.

numbafree

I was going to check the rear diff and transfer case fluid at 15k miles, 180k, right now at 178,500. bought it with 164k. I want to see how 'dirty' it is, so I can determine my change interval (usually shorter than was is recommended). I use redline oil.

ajay60610

To C.D. Newton: Now that i think about it i think the lexus dealer wanted to do a drain and fill the AWD differential fluids[2] and do a flush on the transmission....i opted for a drain and fill for the transmission [30,000 miles ago] so i think i'll do the same this time....not sure if i will change the oil on the differentials, but it has been a long time since i did do a change...heard from a mechanic that sometimes the metal products that build up in the differentials actually help and changing the oil caused problems....not sure at this point...thanks for your help.

shikbas

I did front and rear differential oil change,the oil was bad and worth the change

kickin8

iTrader: (1)

Just drain and fill will do

BlackLexRX

Metals in gear oil are never good, Only in cases of leaking will sludge have any benefit-clogging the leak. Also RX diff bolts have magnetic drain plugs that sit at the bottom of the unit. Any metal debris will accumulate and cling there-a mechanism in the system to prevent any floating metals. I did my rear diff recently at 70k just because it was so easy to do and I live in snow country. Drain plug was covered in very fine grey metal, its like a wet oily metal toothpaste, if you will. Wipe clean with paper towel, refill gear oil and good to go. As others have mentioned, it's best to change these fluids, they are not lifetime or even 100 or 120k like Lexus says. For rear diff and transfer case, drain and fill. At your mileage do 3 drain and fills on your trans. On the third, drop the pan and change the filter, refill and your trans will shift better than it ever has.

ajay60610

To Black LexRx : So a transmission flush is not needed in your view just a drain and fill per your post...not sure this independent shop will do 3 drain and fills on the transmission as you mentioned in your post but i can ask.

I do not have the facilities to do this work myself....the lexus dealer wants to charge me $260 to do a drain and fill on the 2 differentials [transfer case and rear diff]...seems rather excessive to me...cost of 2 quarts of Hypoid Gear Oil API GL5 is $57. on Amazon.

Thanks for your help.

BlackLexRX

I would do the trans at least one drain and fill now. It takes 3 to get most of the old fluid out, but it will shift better with one. As I mentioned, there's also a filter inside the top of the pan too that's nice to get replaced but not absolutely essential. My Lexus dealer has the fluid conversion machine and they do recommend it, and guarantee it not to harm the trans system. It alone is about 250$, here in Colorado. 250ish for them to do the differential and transfer is par on price too, so it's fair-they are high, but if it's the Lexus dealer, that's normal and they typically work carefully and professionally. Rear diff really easy. If u can get under rear of your car safely where it's parked, u can do it, same for trans drain and fill, just up front. Transfer case is trickier due to location and design of drain plug. Search this forum and you will find much guidance on how to do these maintenance items. If it's just not possible, have Lexus do all 3. Should be right around 500$ish and your drive train will be totally serviced for 30K miles at least.

BlackLexRX

If you do it yourself, get Mobil1 full syn gear oil or a comparable oil at your local parts store. That's too much for it and they generally add cost to shipping and packaging due to the fact that it's oil being shipped. I buy it last for about 12$ a bottle.

ajay60610

To Black Lex Rx....Okay..now i understand your post...thanks for your help....am worried that the independent shop may not know what they are doing...may have to bite the bullet and go to the dealer.

Thanks for your help.

BlackLexRX

Use your Indy, that's OK. These are common automobile 101 items for mechanics, they can do it no prob I'm sure. If price is comparable at Lexus, then go there. You're welcome, that's what this community is for.