I've been reading a good bit on here about oil lately. For me this has refreshed my memory about a question I had..... Do most of you buy "special" oil just for the mowers? The reason I ask is because I am a "spec sheet" man when it comes to oil. I look at the specs on the oil I run. Right now I have settled on Mobil 15w 40 the "Million Mile Oil" for everything else I own. All my engines have the same oil in them, mowers and all. But I have 10w 30 in my new one. I am thinking strongly about just using the 15w 40 in it too. The reason is that in order to get the same specs in a 10w 30 I'd have to use synthetic oil, which I don't care for. Also there is so little difference in thickness. Plus the 15w 40 is made to stand up to heavy loads, extreme conditions and off-road use. What do you all think?