Technical Oil additives in engine or gearbox?

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Technical Oil additives in engine or gearbox?

Jun 10, 2007
Hi. What do people think about this? Oil manufacturers say "there's no need to put additives in our oil, in fact you might do more harm than good", yet loads of reputable companies claim their additives do nothing but good. My only experience is with Slick 50, which I used in the engine oil of a P6 V8 Rover. Immediate difference was the engine tickover revs went up from 700 to 800 rpm, so I guess it's claim to reduce friction held true.

There's a very slight transmission whine on the Multipla which I noticed after I'd taken the roof bars off (no bars = no wind whistle). The car has 67,000 miles on it, so I doubt that the gearbox/diff has appreciable wear. What I'm wondering is whether Slick 50 for gearbox use would arrest things.