look, when tetraethyl lead was in the fuel, the car manufacturers recommended 10,000 mile change intervals. or twice a year, whichever came first.

now, benz wants to recommend 15,000 mile change intervals. why? as i see it, to feed their dealers. and by the way, it is not just the cost of the plugs, it is the price of the labor to perform the change-out.

quite candidly, spark plugs in the absence of tetraethyl lead, in a benz engine that gets some high speed running, should go 60k without failing.

the way i view it, the more often i can prevent a gd mechanic from changing any parts the better off my engine is. savvy?