Vic Kucera

Heya...I have been using 10-30 motor oil in my '90 Comanche 4W. Last week I drove from Arizona to St. Louis and back, ballpark 3200 miles. One stint was 26 hours straight, with a few catnaps. The motor oil didn't get dirty until the last 3-400 miles. Have to wonder if the oil is doing its job. What weight of oil are others using? Amazing how comfortable the Comanche is on a long trip.