1989 Dodge Spirit tranny slippage

Ok my tranny slips only when in 1st gear once it shift outs its "ok", I was thinking of adding Lucas Transmission Fix, would it be safe to add that??

I cant think of any reason it would hurt to put in a dose of the 'trans fix' type of additive. Ive used 'Sea Foam trans tune' in a couple of transmissions that are still working fine many thousands of miles later.