I agree with Kirk, but Paul is correct, too. By nature of engine and pressure lubrication system design, internal combustion engines produce oil pressure fluctuations with each revolution of the crankshaft. For example, at 600 RPM, 600 oil pressure "pulses" are delivered to the guage or sender unit each minute. This rate is often too rapid to be seen on the guage, but the guage is still susceptible to wear from these pulses. An inline restriction acts as a buffer to reduce the amplitude of these pulses, reducing guage wear and delivering a stable indication (no needle jitters). What we read on the guage is actually a buffered average of high and low pressures between pulses.
There can be one or more inline restrictions to buffer the oil pressure pulses, including a restricted fitting at the engine or at the guage. Long lengths of small diameter oil pressure line (in our case 1/8" ID) also acts as a buffer.
The oil pressure guage used on most (not all) 150's and 152's incorporates a built-in restriction at the guage connection, as illustrated in the photo below of the guage for your 150M. So, you already have two buffers without worrying about the engine fitting.
(Blatantly stolen images)
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