Please forgive if this is a silly question. I've been thinking of buying a heavy-duty hi-lift jack for my Landrover Defender Td5 station wagon, 110, but am wondering about the jack I already have, the one that came with the vehicle. THAT is "hi-lift" (it has to be, to be able to lift a wheel high enough to change it), so why would I need to buy another one? Wouldn't the one I have do the job, namely lifting my vehicle if the wheels are bogged down?