So anytime someone hits a red barrel now only crude oil comes out no low grade. Any ideas?

Go to your ..\oxide\data\BetterLoot\LootTables.json and look for the following section and make sure that ItemList includes "lowgradefuel":

"assets/bundled/prefabs/radtown/oil_barrel.prefab": {
      "Enabled": true,
      "ItemList": {
        "crude.oil": {
          "Max": 20,
          "Min": 15
        },
        "lowgradefuel": {
          "Max": 10,
          "Min": 5
        }
      },
      "ItemsMax": 1,
      "ItemsMin": 1,
      "MaxBPs": 1,
      "Scrap": 0
    },​

If someone will look for this like me, here is the fix:

    "assets/bundled/prefabs/radtown/oil_barrel.prefab": {
      "Enabled": true,
      "ItemList": {
        "crude.oil": {
          "Max": 20,
          "Min": 15
        },
        "lowgradefuel": {
          "Max": 10,
          "Min": 5
        }
      },
      "ItemsMax": 2,
      "ItemsMin": 2,
      "MaxBPs": 1,
      "Scrap": 0
    },​

I'm pretty sure, this should be default, 'coz players are used to get both items from that red barrel. Hope @Default will read this and apply...