Hi everyone ! Hope everyone is doing well!

I have a Lexus is350 f sport 2017 AWD with 100k miles American specs over here in UAE. Was doing an oil change last week and I noticed there was a minor leak coming out from the front differential. Today I went below the car to check again and noticed the leak has kind of increased and surrounding other areas of the differential as well. Would anyone be able to advise as to why the leak is happening? I’ve never changed the front differential oil since purchase as once when I visited a local garage after 70k miles they said it is risky as it can cause noise from differential after the oil change.

is this true? And If not can I change the oil of the front differential with 75W-90 Amsoil severe gear oil? As owners manual recommends SAW80w-90 but I cannot find that viscosity over here in the UAE.

I’ve changed transmission fluid , rear differential fluid a at 85k miles with no issues. I have attached a photo as well with the oil leak if that helps! Thanks for any help!



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That's the pinion seal leaking, it happens not a big deal, but you should definitely replace as soon as you can. I've seen people continue to drive with really bad pinion seal leaks to the point the differential runs low on fluid and causes damage.

As for the gear oil, you should do you're own research, but from what I've read on multiple websites, it would be perfectly fine to use 75w90 instead. I'm not real sure why that shop told you it will create issues changing the fluid, as I've done many front and rear diff service on lexus, some with over 120k miles, and never created an issue with new fluid.

- Shane

 

hank you Shane for your response it’s much appreciated.

I will go to my local garage and get the pinion seal fixed, I was doing more research and I stumbled upon a thread with a similar issue and it mentions that the whole front differential needs to be removed in order to replace the seal? And if it’s not fitted back in a proper way it can cause differential vibrations after fixing ? Do you know anything about it ? And as you mentioned you’ve done multiple differential changes did you do any particular for the 3IS ? And if so did you use 75W-90 gear oil?

thanks you again.

 

I can't speak on the actual how-to on the replacement of the seal unfortunately, I've never replaced one on these models. It's a tight space, but I feel as though a good technician/shop *should* be able to do it with the differential in the vehicle, but can't really guarantee it.

As for gear oil, all of the diff fluid changes ive done were on the 2 and 3 IS, and I've always had multiple flavors of oil at my disposal so I've always used the 80w90 that it recommends. But again in the research I did, some people almost recommend using 75w90 over 80w90 no matter what the factory recommends. Me personally, I wouldn't deviate from what the factory states should go in there, but in a pinch such as yours, I don't think I would lose sleep over using the 75w oil.

- Shane

 

So here’s a quick update , I replaced all the pinions last year since the start of the thread and everything was fine until today I noticed the leak has started all over again , really no clue how the front differential is leaking again 🥲

 

This is happening to me. How much did it cost to get the seal fixed?? What did you end up doing the second time

 

Hello, I know this is unrelated, but you mentioned that you changed the transmission fluid. I’m curious since I will be changing mine soon on my 2018 IS 350 AWD.

Do you remember at what A/T temperature reading you pulled the check plug during the oil level check procedure? I know there is a range but I can’t find exactly what that specifically is for our A760H transmission

Thanks