I got a Corolla with a 1ZZ 1.8L motor which isn't normally seen as an engine that's tough on oil.I use M1 5W30 throughout about 95% of it's 54K miles. I changed the oil this Feburary and the oil currently has 3900 miles on it as of today.The color is a slightly brownish tinted amber with no noticible consumption shown on the dipstick. My drive to work takes 35 minutes so the engine gets fully warmed up everytime I use it. I am planning to change it at around 7.5K but that would take a year to reach.Would it be better to just go ahead and change it earlier as in twice a year instead of once with the 7.5K OCI? Maybe 2 dino oil changes a year might just work just as well in this application and be cheaper. What do you suggest?