Quick question forum i have a 2005 LS430 with temperature gauge fluctuation when i drive the car it goes above the half mark an stays there an the fan is constantly on i change the radiator in January i havent had the timing belt changed i don't believe i did the bubble burst air procedure any ideas?

How are you checking the level?
Where do you notice the fluctuation?
When do you notice the fluctuations?

Can't keep any coolant in overflow tank for years. Some say the hoses may be blocked to overflow tank. Mechanic/Dealer has no answer and doesn't want to bother except topping it up. One of the idiosyncrasies of car. It never overheats and radiator seems fine. Had coolant replaced lately. Same still. Lasted 2 weeks in overflow tank. Radiator level seems fine. I've gone years like this. Just FYI.

Sounds to me like your overflow tank has a leak. This was a common fault on the LS400 where it leaked coolant onto the alternator.
On the LS430 the tank is either on the radiator or else on the inner fender. That coolant is going somewhere. It can't just vanish.

The "overflow" tank is there for 2 reasons.
1- To take excess coolant when the main circuit heats up and the coolant expands.
2- Feed coolant back into the main circuit when it cools and the coolant contracts.
If there is no coolant in there, you are low on coolant and the system is not working as designed.

Thanks. Need to find someone to care. I had alternator go at 150k miles and guy mentioned some coolant residue, but he was a chain (Firestone) and didn't want to fix it / figure it out... But you are right, an if radiator ever leaks I would not know. I have not seen obvious coolant beyond tiny amounts if any, but I could be missing it.

i edited my original post

My issue with my car temperature fluctuation has been solved it was the thermostat an i also had timing belt change..

I cant find the thread, but the hoses for overlow chemically 'wear out'. The small hoses swell, and block, spurt, and leak causing small amounts of coolant to weep. But the hoses look fine. It just age and heat cycles etc.

Certainly you can treat this as parts cannon, as a fix. But if you're just on train of some coolant weeping at overflow, I think there are 2 or 3 small hoses to refresh.

I have actually seen that info, but it's a good reminder, thanks. Next year for its 20th anniversary assuming I still have car (I should,...) I'll change diff fluid and trans fluid at dealer (been 10 years or so) and will direct them to do this if they don't hem and haw. I'd rather not prescribe a fix, as I am not a mechanic, but starting with overflow tank hoses sounds reasonable. I'd ask them to inspect again, but they never find a problem with radiator, etc.

Broader question: I have never changed radiator hoses (main hoses) or others (heater?) on my car. They just last, but nothing is forever. I just did coolant replacement, too, as it was almost 6 years (oops, I try for every 5) so not looking to do it soon unless I need to, unless you can just top off coolant vs a more expensive complete drain/fill after. When is a good time to do that? Do they come off anyway with a timing belt (with water pump) job? That'll be in 3-4 years if I still have the car, so a while off yet.

My car has 160k and is 19 years old. Is there any reason to worry or are core coolant hoses so good that no preemptive need to change without visual signs of a problem ? I've always changed my serpentine belt every 60k/8-9 years or so in my cars... but not hoses.