I just finished installing the sun pro 1 1/2" gauge kit and now I'm wondering about the operating oil pressure. Can anyone tell me what I should be expecting? When the engine is first started I'm running around 24-26psi, but after it is up to running temperature and at running speed for mowing, it drops to around 18psi? I am running full synthetic shell Rotella 5w40 oil. Should I be running a non multi weight? Is there something else going on ? or what?..... Any thoughts would be appreciated.