Hey everyone,

I have a used Lexus is350 2017 f sport with 98k miles.

as per lexus service history with previous owner there was never a change for the front and rear differential oil. Now as it is out of warranty and I checked with my local garage they said they can replace the front differential oil but after changing the oil it ‘might’ cause sound to appear in the front differential. I changed the rear differential and the oil was pretty clean but advised me not to touch the front differential. I have even drains and filled transmission oil at 85k miles which was the first for the car luckily with no issues yet.

any advise if this is true that changing the front differential oil at 98k miles can cause any noise from the front differential ?

 

They say it's lifetime but I've been changing my differential fluid for rear every 30k and front every 60k since the car has a rear wheel drive bias. Feel like if you change it now, it's not a big deal, it's not similar to changing transmission fluid in a car which has had over 150k miles which could lead to damaging the transmission if that's what you're getting at.

 

thanks for the input , are the differential oil same for the front and rear ? It’s 75W-90 for rear can that be used in the front as well ?

 

Texted my Lexus advisor for you today, he said the oil is the same but if you have a limited slip differential, the rear differential will need an additive when the fluid is changed. From what I recall, I don't 2014-2020 IS's ever came with a limited slip differential

 

Amsoil severe gear will treat you right

 

FWIW, AWD ISes do not have a rear limited-slip diff.

 

I went to my local garage today and he Informed they had a done front differential fluid change on different cars and some of them started creating weird sound but some are fine. They also said they would not take the responsibility if any sound occurs from the differential and informed me to drive it as long as it’s working. I checked in other authentic service providers as well and they informed the same. My rear differential oil was changed without any issues. So my question is will I be okay to drive it as long as I could without any issues? As I’m kinda scared to take the risk now of changing the oil

 

The service manual in the back says to inspect the front diff oil (AWD) about every 15k miles or so. So not sure that one is considered a lifetime fluid.

 

According to the manual for a 2018 of the same model, they are not the same. The front requires 80W or 80W-90 GL-5 or equivalent. The rear requires 75W-85 GL-5 or equivalent. Perhaps the 2017 is different.