Back last February I bought my first car that requires the use of synthetic oil over the old school type of oil. My 2011 Cadillac CTS 4 with 84,500 miles also has a oil gauge that will tell me the oil status. When replaced it is reset to 100% and then begins to decline. I know under the old oils you were always told the 3 month/3,000 mile change plan. But with the newer oils I’ve seen some things that you can now go a full year between changes. Going off my “gauge” I have gone a little over 6000 miles before it go to zero and had it changed out.
So exactly with the newer better oils how do you know when to change out? Also about 75% of my driving is in city mileage over freeway mileage. So should it need changing more often depending on type of driving you do.