1 oXTZ is always equal to 1 XTZ. Make sure to always exchange your oXTZ/XTZ directly through the UI.
oXTZ (objkt XTZ) is a form of wrapped XTZ (or tez) the native currency of the Tezos blockchain. oXTZ is always exchangeable at a 1 to 1 ratio for XTZ. The easiest and best way to exchange oXTZ for XTZ is directly through the UI.

Wrapping/Unwrapping oXTZ

Click on the wallet icon to show the balances, here we see 3.00oXTZ.
Clicking on "Exchange" brings up a form, the up/down arrow lets you switch the direction of the conversion: XTZ to oXTZ or oXTZ to XTZ. Here we see 3.00oXTZ about to be unwrapped to XTZ, after this operation the user will have 14.97 XTZ and 0 oXTZ.