As Ramasamy say There is no standard value depends on several factors, including changes from one tissue to another, so you should always have a control group against which to compare.
SOD, glutathione peroxidase are the enzymes which reduce the ROS (Reactive Oxygen Species). Reduced glutathione (GSSG) is one of the product of reduction of ROS. Malonaldehyde is the indicator of lipid peroxidation. So measuring their levels helps to indicate the oxidative stress. Oxidative stress differs from tissue to tissue. It also depends on the diet provided to the animals. The only way to know the presence of oxidative stress in a group (of animals) is comparing it with control group which has been exposed to the same conditions like diet, handling, etc., as that of the test group other than the administration of the test substance.
Different assay or kits are expected to have varied ranges. Hence, the control group will reveal the correlation to other bio markers as quantified. Enjoy.