I bought a dealer demo 03 Monte Carlo ss.It has the 3800 series 2 v6 engine.The car had 6900 miles on it when i bought it.First oil change with dino was at 3000 then when i bought the car at 6900 i used 5w30 Mobil1.I changed the oil at 14,400 miles and used Amsoil 5w30 this time.Last two changes i used the longer pf52 style filter.The car has the oil life system on it and it never came on before i changed the oil.I have read this site for a while and have seen good uoa reports with this engine going around 10,000 miles with synthetic.I have 6 quarts of Amsoil 10w30 and a 5 quart jug of Mobil1 10w30 to use up or get rid of.If i stay with synthetic i will continue to use Mobil1 and Purlator Pureone filters.The 5 quart jugs are like $19 bucks and the filters are like $4.So $23 oil changes.If i go with dino it will probaly be Havoline like about $1.20 a quart and Super Tech filters for $2.So about $8 oil changes.I change my own oil and do my own service work if i can.I drive 25 hiway miles to work and another 30 miles back home.About 5 of those are city miles since i have to make a stop on the way home.I plan on keeping this car probaly 5-6 years.So i am figuring at least 18,000 miles per year.If i stay Synthetic it will be 2 oil changes a year $46 bucks.If i go dino it will be 3 oil changes around 6000 miles for $23 bucks.I cant convince myself to use Amsoil only once a year.Just too many miles on a oil for me.What i am having trouble with is convicing myself to stay syn or go dino at next oil change.What do you guys think and or recomend?Am i wasting money useing syn since i most likely wont keep the car long enough?I also changed the trans fluid to Mobil1 synthetic atf and added a trans oil cooler when i bought the car also.