I've just noticed after using the same gas station for years, some pinging under hard acceleration. The car has plenty of power. The Octane rating is 91 which is what I always use without issues. There is no pinging under normal driving. No warning lights are on. Should I be changing my gas station? Does the LS430 require 93 octane?

 

Try changing your gas station first. You can always add a little octane boost and see she acts. Don't forget, ethanol lowers octane level even more. These cars were designed to run best on 93 but the knock sensor should retard the timing enough to prevent any serious detonation. Yeah, just need to test it and ideally run higher octane. I always run 93. Better mpg as well.

 

Yes you need to change gas stations. It's not uncommon for stations to have 87-89 octane filled in the 91-93 premium tanks and still charging full price. Or just bad watered down gas etc. I notice the quality of gas varies everywhere as my bike will ping and detonate like a pig if the octane isn't 93+ so I can feel the difference from fill up to fill up and station to station.

I only use 93 in my car. Think manual calls for only premium but not sure what octane they rate it at 91 or 93.

 

Here is the direct quote from the owner's manual:

GAS STATION INFORMATION
Fuel selection:
Select premium unleaded gasoline with an Octane Rating
of 91 (Research Octane Number 96) or higher for optimum
engine performance. However, if such premium type
cannot be obtained, you may temporarily use unleaded
gasoline with an Octane Rating as low as 87 (Research
Octane Number 91).

Ignore the RON (higher) numbers, gasoline in the US is labeled by Motor Octane Numbers (the lower ones).

I don't know where the rumor started that 93 was required, but it is not true. The engine was designed for 91, and putting anything higher in the tank is simply a waste of money - and it does NOT add to power output.
Using lower octane gas will lower the engine's output because the knock sensors will detect pinging (mainly under acceleration or uphill driving), and retard the ignition timing.