Just finished changing plugs and thermostat in my L300. Not an after work task. More like a weekend, or every night afterwork task. The clamps are a little tricky if you want to reuse them. Mostly, the issue is how much you have to remove to get to everything. If you have never changed the plugs, you may want to coxider changing the thermostat since you ate halfway to it anyway.
I love my V6, when I dont have to work on it. The L300 is fast, holds a family of 5, and gets 30mpg on the road. Great car!
Good luck.

I really don't like that Opel setup, never did amd would have never bought one. Just like the Astra GM shoved down the throats of Saturn stores. Not worth a **** in my book.

For every one thing, you have to remove 3 to 5 others
 

I am currently suffering the same frustration of having to remove up to six things for every little thing you want to fix or replace, such as spark plugs.

I decided to replace the clamps with traditional hose clamps. The intake runners are not going to looks as neat, especially that I am replacing only those clamps that I had to remove.

I think the thermostat is the worst. It must have been designed by someone inspired by big law firm mentality of how they can get as many billable hours out of anything. The amount of time it'll take to remove all in the way will dwarf the amount of time it takes to actually work on the thermostat and its housing. I'm still debating whether I should replace it preemptively as I have a lot of things off already as I am doing a 100K service, or I should draw the line and deal with the thermostat when it fails.

You've already got all the crap out of the way to get to it. If it were me, I'd put a new one in it and not worry about it for another 100,000 miles or so. Why wait for it to fail?

Thermostat, oh thermostat, they really couldn't have put you in a worse location
 

Well, I'm leaning towards it, but first I need to put the front of the engine back together (at this point there is no time pressure, so I'm taking my time). Until I put the right engine mount back in and the engine comes off the engine support bar, I cannot start on the thermostat since one bolt that holds the coolant pipe is the same one holding the engine lift loop, which is currently busy.

At least, on the L300 the intake manifold is a three-piece design. I had to take the two intake runners off to get to the spark plugs. The center piece that is on top of the thermostat is still on. Compared to the one-piece design shown in the video on page one of this thread, the three-piece one may be a little bothersome with the clamps, but overall I think it is easier than suspending that one big piece off the hood.

All I know is that if I go to purchase another Saturn, it won't be one with the V-6. Too much of a pain to work on. I'll stay with the four bangers, thank you very much.

Spark Plug Access on L300 V6's
 

I am not familiar with all model years of the L300 V6 by any means. On the 2004 V6, the intake manifold is a three part design compared with the the Vue V6 depicted in the video in this thread. So, one does not need to remove the entire intake manifold. Rather, there are two intake runners that need to be removed to be able to remove the coil packs and then the plugs. This is easy and quick on bank two (cylinders 2, 4, and 6), and it is easy and involved on bake one as there are a bunch of things mounted on the intake runners on that bank; still, not difficult just lengthy (compared to how long it should take you to access the plugs.

I am posting this reply, considering the original date of the original post in the thread, because someone might be researching this (like I was six weeks ago) right now.

Thank you for taking the time to do so

Completely different set up on the vue, l300 is a littler
 

Moot point, man. This thread is between 3 and 4 years old now.