Wipe her dry and examine her again.
You are quite correct: Oil plus Rust equals GRINDING COMPOUND. NOTHING will remove original finish (bluing in this case) much faster. So you avoid the combination.
If there is actually rust there, attack it with DRY steel wool, FINE or EXTRA-FINE grade. When you have the actual surface rust off, there might be a bit of colour left. Try for that, too but if it dosn;t come right off, then leave it.
Wipe her DRY again.
NOW you OIL the rifle lightly.
No more problems.
Hope this helps.
