I think only valve problems can give zero compression but I am not positive. I think bad rings will always give "some" compression. I had a cylinder with bad rings on my old Toyota and it burned a ton of oil and the compression was somewhat low but nowhere near zero. I suppose a hole in the cylinder could do that also.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra