Trying to do partial flushes of PS by emptying the resorvior and adding new fluid. Used Mercon V, should be plain Mercon. Will this cause any problems?

it shouldn't, the weight and density is pretty similar for those purposes.

Like the Dr said it should be OK. If you read the back of the type 5 bottle it should say that it is compatible with previous Mercon fluids. Anyway the one I bought does.

Thanks! The Valvoline Mercon V bottle states backward compatability, the CastroL V does not. Anyway I feel confident w/my ps system now.