hey guys, i currently have a 97 bmw e39 540i 6spd. its a 97 so its a non vanos engine(m62). im currently running rp 10w30 in the engine and synchromax in the trans. i've used the synchro before in my e36 m3, good results in both cars. switched from redline d4atf to the synchromax in the m3 and noticed a improvement in smoothness of shifting. real question here is what is in rp that gives the products its purple tint? those of you who have used it know what im talking about. its very evident in the synchromax that it is purple in color and even the oil has a purpleish tint to it. ive always been rather curious about this, marketing ploy prehaps? also, out of all the synth oils available, where does rp sit on the list in terms of quality and esters etc? what would you guys say is the absolute best synthetic oil available? meaning the highest group? redline? thanks..