Drained and refilled coolant on 2009 LS460 AWD couple weeks ago. Vehicle has over 225,000 miles.
DIYer on ramps in garage. Found it difficult to access cylinder block drain plugs...asked dealer for help...no help.
Searched Toyota tech info website, again no help. Searched multiple Lexus forums, again no luck.
My belief after many years is that there is usually a trick to certain tasks, you just have to find it.
If my write-up is more appropriate in another thread, I will not be offended.

Spent time under car looking for access...ultimately discovered that you can insert a 3/8" drive long extension (prox. 12-15")
with a 10mm swivel socket just under and outboard of frame rails.
On right/passenger side: you can see drain plug from behind drive axle, and insert long extension socket in front of axle.
On left/driver side: you can see drain plug from in front of drive axle, and insert long extension socket from behind axle.
These positions are not perfect, but very close to perpendicular to the block, and nearly horizontal.
(if I was a small man with small hands, perhaps there is a way to get a wrench inside the space between the block and the frame, but I could not do it.)

Don't take drain plugs completely out, simply enough for coolant to drain slowly but completely.
If your vehicle is like mine, it was previously over-torqued by the last (dealer) mechanic, and a bit corroded.
I sprayed the drain plug with penetrant (pick your favorite, such as liquid wrench) about every 12 hours for 2 days
(4 times total has usually been successful for me on most stuck fasteners).
Also, after the 2nd spray, tap lightly on the plug (long extension)...don't hammer it. This usually aids/shocks the penetrant in seeping into the threads.
Drain plugs opened with no issues after that.

Per above, access was sufficient to apply proper torque using a torque wrench to drain plugs when finishing the job.
Replaced the thermostat and water pump as part of the job, along with fresh rubber hoses to radiator.
Followed factory spec on refill procedure, which worked as stated in repair manual.
A couple days later, drove it about 750 miles on weekend outing...no issues.

Hope this helps the next DIYer that attempts to drain and refill coolant.
Not sure if under car access for 2WD Lexus LS 460 is same, but I am guessing it is.
I saw nothing in the repair manual or parts diagrams that would cause me to believe they relocate the drain plugs based on the model/drivetrain.

 

All the services for my 2011 LS 460 L AWD have been performed by the same dealership from the day I bought the car

Although I have just 30,000 I had the dealership replace the coolant even though they said I had time I also had all 4 tires replaced with all season

The LS is my all-season car as it handles great in the rain or snow so I use it 7 months out of the year

My 2017 BMW 750 I X drive with the M sport cost $20,000 more than the LS and although it is fun to drive with a 0 -60 in 4.3 seconds it cost a fortune to maintain

The only reason I did not buy another Lexus is the new grill is hideous looking and even with the twin-turbo 6 cylinders it does not come close to the BMW 8 twin-turbo and the new LS owners complain about it constantly

 

I attempted to replace my coolant today but could not open the block drains. The driver's side was behind the exhaust manifold and heat shield. I could not get a wrench on it. The passenger side behind the alternator. I was successful to get a socket on it but my extension was too long to get the ratchet in place. I settled for draining the radiator which removed about 50% of the old coolant. Here are some photos.

Do you think the dealer has a special tool to open these drains?

 

Did it at the dealer, I guess was around $100, not too bad....

 

A dealer may just do a simple drain and fill. Only opening the radiator drain because it's not labor intensive. At $100, there's no way they can make money, completely draining, flushing and refilling the LS. Just do the math. Hourly labor + cost of coolant. I recently paid Toyota $150 and they did the quick and inexpensive route. Perfectly OK like this. It is long life coolant. Just do it again when convenient. This is what happens with transmission fluid, drain and fill. It dilutes the old fluid with new. Do it several times and it's mostly new fluid. Not perfect but a common practice on the LS.

 

WRONG

I took my 2011 LS 460 L AWD last year to a Lexus dealer and they said your not ready yet I said I know do it anyway as I had 30,000 miles on it and it cost me $102. plus tax and was told come back in 9 years

They "make money" as I have my oil changed every 5,000 miles Mobil 1 and replaced my tires @ 25,000 miles and I do all the services required before the book said to

I also had the battery replaced every 4 years even though it worked

The reason my LS has so low millage as I drive my BMW 750 I M Sport a lot more as my LS is my winter car when there is a possibility of snow

As a plumbing contractor I know how important preventive maintenance is

 

My dealer charged $300 for mine.

 

That is insane....they don't even have to mix the antifreeze anymore.

 

2 of these, about $26 USD and a rad drain= $300 I shudda bin a mikanec

 

So is everything else I get there (see my post on my $150 oil change)!