I'm at 30k miles on my 2014 IS350 RWD.

Should I drain and fill the transmission fluid? and replace rear diff fluid?

I'm in socal, so not much of temperature fluctuation. What do you think?

 

Trans fluid + trans filter change every 80,000 km ( not sure about miles )

Diff fluid change every 40,000 km ( not sure about miles )

 

I say wait till 50k. I just did mine at 49k and it wasn’t too bad of color. I would do the rear differential tho. At the 49k mark I did tranny drain/fill and new spark plugs. At 40k I did the rear and front differential as mine AWD. Next up is coolant flush and I’ll be good till next interval.

 

i had the dealership do both at around 50k miles. also in socal.

 

I know the miles are low but it is a 9 year old fluid...

 

Yup, with this being 9 years old, I'd do it anyway and have the drain and fill done. Now the age of the fluid may not even matter scientifically speaking, but better safe than sorry!

 

Agreed. Fluids like this still have a shelf life.

 

I waited until 100k and should have done it a *lot* sooner. I stupidly went by the service manual intervals instead of doing it preventatively. Fluid drained at 100k was pretty dark. I just did another flush at 110k to get it all cleaned out. No problems with the transmission, but I'd definitely say do it at 60K miles. It was only $150 from a fantastic shop here in LA.