You should follow up with a leakdown test, which will tell you where cylinder #5 is losing its compression. Could be the rings, the valves, or the head/gasket/block seal. Might help you make up your mind on what to do about the problem.

Does the car start and run well or poorly, burn or leak oil or coolant, etc?

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970