Synthetic oil.....5W30 Mobil1 or valvoline
10w30
10w30 Your oil cap on the engine block will have it printed.
They take Regular or E85
They take Regular or E85
7.5 quarts
it take dexcool its a orange antifreeze that is approved by gm.
Premium Unledded fuel.
To reset the computer on your 2003 Cadillac CTS after changing the spark plugs, you can disconnect the negative battery terminal for about 10-15 minutes. This will clear the engine's diagnostic trouble codes and reset the computer's adaptive memory. After reconnecting the battery, start the engine and allow it to idle for a few minutes to let the computer relearn the engine parameters. Additionally, you may want to take the car for a short drive to help it recalibrate.
The 2004 Cadillac CTS typically requires 5W-30 engine oil. It's recommended to use a high-quality synthetic or conventional oil that meets the API (American Petroleum Institute) standards. Always check the owner's manual for specific recommendations and requirements for your vehicle.
Range Rovers all typically take 5W-30. If you are still unsure, the oil reservoir cap should have specs on the top of it telling you what is best for your specific engine.
The 3.6 engine can take regular (89 octane)
The only way to fix it is to take it to the dealer and have the whole gage cluster replaced there was a service bulletin out on this from Cadillac and they will pay for part of the cost.