What type of oil do I use 1850 pm0401850 - Coleman Powermate Powermate 5000W Generator

Oil Type. Use new good quality oil such as SC, SD, and
SE grades. The oil to be used depends upon the temperature
at which the engine is operated:
Summer: (temperatures of over 40 degrees F/10 degrees
C) SAE 30 or SAE 10W-30, SAE 10W-40
Winter: (temperatures of below 40 degrees F/10 degrees
C) SAE 20 or SAE 10W-30

Manual here:

http://www.powermate.com/pdfs/2007/11/12/pm0401850-52.pdf

That has one of the small Briggs and Stratton engines. That engine uses ONLY 30 WT engine oil. Nothing special get it as any auto parts store. DO NOT USE 10w-30 or other multi viscosity oils. ONLY 30 wt.