The powers that are at OSU have decided to include 1970 as a National Title season. Of course, the Buckeyes were 9-0 and ranked #1 in one poll or another BEFORE the Rose Bowl loss to Stanford. So including 1970 in the pantheon is somewhat disingenous. Woody might be the first to admit that this is a thin thread on which to base a title claim.
I've noticed some schools include retroactive (pre 1936) seasons as National Titles. If so, why not swap 1970 for 1916 as an OSU National Championship season? The Buckeyes, led by Chic Harley, went 7-0 while winning the school's first ever conference championship. Included were first ever wins against Illinois and Wisconsin (one point each!) and an 128-0 victory over Oberlin. The Buckeyes were undefeated. Who can say they weren't the nation's best team with any certainty. It is difficult to argue against a perfect season.
OHIO STATE: National Championships
1916, 1942, 1954, 1957, 1961, 1968, 2002