Careful with 20w50 in cars like Crown Vics and Grand Marquis. Those V8s can't handle it and have to have 5w30 or 10w30 at the maximum. I learned this one the hard way thinking 20w50 would help my 277k 1994 grand marquis.sythetic is great ,just don't use it if your switching and have an existing oil leak...it makes them worse...and whatever ya do ...don't use quakerstate oil ...worst oil protection ive ever seen after teardown and inspection......If you have an older car or vehicle ..I like to run 20w50w its real thick and offers great protection for older vehicles....Also 1/2 quart of dextron automatic transmission fluid added to a full tank of gas ,will clean the pistons/carburator/F..Injection...