Hello team!
I am trying to keep my IS350 stock with great feel as new. But I noticed that the rear shocks are leaking. Should I go OEM shocks


or aftermarket rear shocks?
Team!
First and foremost "Thank you" for every single suggestion you all have made. I decided to order OEM from https://www.lexuspartsnow.com/
Cost 104.00 each with it's Lexus warranty. Total with shipping 217.00. It will take a few days to receive.

 

If the car is stock I would just stick with the OEM shocks.
You might also find when looking for an aftermarket option, there really isn't much available for stock replacement.

 

Thank you for heads up.

 

OE shocks all the way. This goes with what I always say about high performance--items tend to wear out faster, requiring more frequent replacement. (wear this as a badge of honor if you drive a car that performs) --not necessarily the leaking though. That can be due to other reasons. Catastrophic failure possibly from impact, torn dust boot/dirt ingestion on shaft seal, improper install--shaft stress due to pre-load. Or just plain break down over time.

The 3IS is a great handler and this is just the territory. To keep your 3ISs handling great, somewhat regular damper replacement is ideal as their performance slowly degrades over time. What I found out from my research in the other car community is that internally, OEM shock makers of high performance dampers figured out the half-life of dampers to be around 40,000 miles. So at 80k miles, figure your dampers are performing relatively poorly to new, even if they aren't leaking. Again.. this is from world class OEM shock/strut manufacturer. The oscillation of the shocks/struts generate tons of heat (particularly on a car with stiffer springs) which as you know--heat kills everything.

Curious about OP's car, any suspension mods/lowering, and how many miles?

The rear dampers on the 3IS seem to leak first. It could be the diameter of the piston/shaft is too small for the weight and duty of the car. I wonder if for the 2021 model any changes were spec'd.

 

I replaced my leaky rear shocks with KYB shocks. Don’t notice any difference in ride or handling. Got them from RockAuto, KYB 5540004, $45.79 each.

 

When I had looked previously for shocks, KYB was the only aftermarket option...and they indicate it was for the Base model only...assuming to mean the F Sport wasn't included.
They don't have a replacement for the front either...only the rear.

The OEM shocks are about $99 USD...so twice as expensive as KYB, but also not crazy expensive...$100 for a quality shock is reasonable.
That doesn't mean KYB is inferior...they have a pretty decent reputation.

 

If you're happy with the way it handles, I say stick to OE shocks.
If you're doing the work yourself. throw the part number into google/amazon/whatever and search out deals.
If you're not doing the work, get prices from your local dealer & your preferred independent, make sure to explain that you want OE shocks not an alternative.
$100 a corner in parts is reasonable; try to price out VAG/BMW/Merc stuff.... yikes...

 

My shocks are blown. Wondering if replacing shocks with the ones suggested above would benefit or would just end up wearing out in no time.

 

I would move up to the F Sport shocks since you have the base model. You could do the same to the front when/if they go.

 

Wondering the differences between 48530-53300 and 48530-53310
MARK 48530-53300 - 5.2 pounds
MARK 48530-53310,F SPORT - 6.0 pounds

 

How about F SPORT rear shocks (PTR13-53140)? Anyone try those? Does it fit both F Sport and Base models?

https://www.oemvehicleparts.com/oem-...t-s-ptr1353140

 

The difference is basically the dampening effect...the fitment is the same, but one is meant for the non F Sport for a nicer ride, and the other for the F Sport tim for a more sportier ride.
They will fit both base and F Sport models. You may want to check and see if the shock is any shorter than the stock ones...and the F shocks are meant to go with the F Lowering springs.

 

Thank you Sasnuke.