I picked some of this up for my car and was going to go replace my tranny oil today in my 5-sp

I picked up some 75W90 Royal Purple from my local parts store.

I was reading the label a little while ago and it says it meets the GL-5 lubrication specs. This is safe for my 88 tranny isn't it? I thought I read somewhere that Gl-5 oiils will incinerate my synchros and is only good for the newer trannies.

Is this true or am I just going nuts?