Hello everyone,
I am a new member and I have a couple of questions on my 2001 IS 300. I have bought the car from a dealer a year ago and I do not have any service records. The car currently has 80 K miles.
1. If the tranny oil never been replaced, is it OK to replace it now or will it cause issues?
2. The rear suspension made a clunking noise every time I ran over a bump. I had it checked out and they told me that rear struts had leaked out but the mount was OK. I recently install a pair of struts and ride has improved and the noise is almost gone. But I still hear a noise time to time but not as bad as before. The rear suspension does not feel like the front. Can you tell me what else could be potentially wrong?

Thanks,
Sam

You can replace the fluid, but I wouldn't advise doing a tranny flush. Just drain and refill. Make sure you use Toyota OEM trans fluid.

As for your rear clunking sound, what did you replace the OEM struts with? Some aftermarket struts can make that noise, and you may want to inspect the sway bar endlinks and the control arms. If you drove with that bad strut for awhile you may have damaged, or worn out some other parts that are now contributing to that sound.