The trick is realising when it is actually better, and when it just isn't.
But a lot of businesses make a lot of money doing just this.
I agree with this.
There are a lot of aftermarket products out there which do make the 306 as a package 'better' than Peugeot made it. However, gearbox oil is not one of them.
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"Supercharged - 454.1bhp/317.5lb/ft"Peugeot 306 GTi-6
2000 (X), Moonstone