This is my MIL's recipe that she adapted from Southern Living:
Mandarin Orange Cake
1 pkg yellow cake mix without pudding
1 [11 oz] can mandarin oranges, undrained
½ cup oil
1 [15 oz] can crushed pineapple drained
1 [9oz] carton frozen whipped cream, thawed
1 small pkg vanilla instant pudding
Combine cake mix, oranges, eggs and oil. Beat 2 minutes at high speed of electric mixer. Reduce speed to low, beat 1 minute.
Pour batter into 3 greased and floured cake pans (three 9" rounds). Bake at 350 for 20 minutes. Cool in pans, remove, cool completely. [I froze them for several days so they would be easier to frost and frosted them the day we ate them.]
Combine 3 remaining ingredients, beat 2 minutes at medium speed, let stand 5 minutes or until mixture reaches spreading consistency. I actually refrigerated the frosting
so it would not be so runny. Spread mixture between layers and on top and sides of cake. Chill at least 2 hours before serving. Store in refrigerator.