in my opinion i don't think anybody should use oil thicker than 10w-40,on my trucks i use 10w-40 and on my wifes car 10w-30.most ppl think thicker oil is better specially on high mileage vehicles.if you take care of you stuff it should last a long time if you haven't notice on newer cars they are running 5w-20 much thinner oil,reason is they want the oil to circulate quicker also they running oil pres.at a lower level on idle as low as 10 psi.having 20w-50 oil just don't make sense to me coz it will not flow as fast as lighter oil specially on start-ups. that's just me. johnwhat's everyone using? I am in texas and have been using 10w30 on all my cruisers. should I be using something thicker for the 3fe?