those letters would not tell you what's what & the online info that a mfg has posted for their products may be suspect(just from the little I've read up on this). I think the best would be to have a sample analyzed or speak with some who has has a particular sample sent in & choose something(or a combo)(that has 1200 or was it 1500 ppm). I've seen the caveats about mixing & matching different additve blends but I'd rather overload or have a bad combo(if that is possible) than not have enough protection & prematurely wipe a cam/lifter. It's not an easy choice as there are alot of ways to go on this.