Coming out of a 97 Camaro RS 3.8 and into an LS1, night and day of a difference! However I just have a few questions... My Camaro V6 at idle ran the temp to about 210 at the hottest point of the day, and usually stayed below the quarter mark when I was driving especially at highway speeds... My LS1 is different... 210 While driving no matter the conditions however it just stays there, never goes past that... So I'm curious what do LS1's sit around as far as temperature goes?

Can I switch to Mobil 1 with 42K on the clock?

and do these cars actually come with a "change oil" light?

and finally, dumb question but on the freeway, if I wanted to play it cool, what speed would probably net the best MPG? I was thinking 60 MPH...

 

50-60 mph is going to be your best mpg speeds. Cruise control will help some too as long as the terrain is flat. Switching to synthetic is fine. I might suggest Castrol Syntec 5w-30 over Mobile 1. It's a bit better according to the oil gurus. Yes, your car came with a change oil light. But, I wouldn't trust it. To reset it, turn key to run position with the motor off and hold down the trip button for ~10 seconds. Change oil light will flash to indicate a reset. Stick with 3-5K mile intervals if you're running synthetic. And lastly, the temp guage is a dummy guage pretty much. Do a little searching in this forum and you'll find out why. If you overheat or are just warming up, it will reflect that. But, typically it will hang around 210 no matter what. Good luck with it and have fun!

PS - get yourself some subframe connectors...

 

The benefit of sythetic is longer oil change intervals. If you;re going to change every 3k, you might as well run conventional oil. Synth will also allow an engine to use more oil. 01-02 LS1s are known to use more oil than others, plus they tend to have more piston slap issues. I never used oil until I ran synth the went through 1/2 qt in 3k miles.

I got my best of 30 mpg running 85 mph. That tank of gas also had a nice 120 mph burst. It depends on if you're an A4 or M6.

The change oil light is not a sensor. Its just a computation done based off various engine data.