I've never seen a cleaning kit like that. I'm betting it doesn't really work. Why not just remove them and send them out for the good ultrasonic cleaning and you can see how they all flow.

Every so often I'll put a can of the berryman B12 in the tank. I guess it helps but I don't really know. 300 miles before every oil change I'll put a can down the oil cap. There's still carbon everywhere but the sludge is definitely way less than when I got it. It's more aggressive than the sea foam.

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'05 E53 3.0 6mt
'17 F30 340ix 6mt
'96 E36 328is, in progress