I've got a neighbor's Poulan chainsaw here, and the manual says to use the Poulan brand 40:1 in the gas and Poulan chain oil or "a good SAE 30." My own saw is a Stihl, so I have the Stihl 50:1 and Stihl brand chain lube. Is there any reason whatsoever to NOT use these in the Poulan? Or, more to the point, can I tell my neighbor to just use whatever generic 2-stroke and chain oils they have at the hardware store? I believe the 2-stroke oil they sell there is also a 50:1. There's no Poulan brand anything around here.