22re toyota and I have always ran non-energy conserving 10w-40 oil Castrol conventional. However recently 10w-40 non-energy conserving is hard to come by unless you go to a parts store where it is extremely high. So I took your advice from the stream the other day and went to walmart and instead got 10w-30 Castrol conventional but this stuff IS energy conserving its all they sell. Should I worry switching my 300k engine to energy conserving oil?