2006 Saturn Ion engine oil

Why would you want to use that have of a weight of oil?Thats too high of a weight for that engine.Stick to the recommend weight that's your best bet.

i thought the thicker the oil is better for the engine. what type of oil and weight should i use in this engine?

I would use 5w 30 oil valvoline thats what i use but castrol or mobil is good.If your not burning oil you can use synthetic oil but if you are using oil i wouldn't use synthetic oil.If you use too heavy of a oil over what is recommended it can effect fuel economy etc.Also in some engines it can set off the check engine light or cause other problems.

I bought some supertech sae 5w-30 motor oil (conventional) is it ok to use it? I add a quart of oil between changing, do I need to change oil filter every time I change oil?

The super tech oil i believe is the Walmart house brand oil i have no idea who makes it.If your burning oil then i would conventional oil.Also yes you replace the oil filter every time you change the oil.

is that why i havn't been getting good gas mileages, will high weight oil cause my car to burn more fuel? i been using 10W-30 the manual recommended 5W-30.

Yes higher weight oil will negative effect mileage if your not burning much oil between oil changes then yes go with the 5w30 oil.