I live in the Southeast. SC and I use to run Castrol 20w-50 all the time until I found out that the heavy oil in the summer time could cost you power. I have been using Castrol oil 10w-30 ever since am pleased with it. I have a 93 sub. and 94 elderado and both of them recommend 10w-30, so I figured why not the 71 with 86 305 H.O. TPI. Sure makes changing the oil easier with only one oil to buy. Really think it has todo with climate,miles on motor mostly though it's just to the personal feelings of each.
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Andy
71's Are for ever!!! or 67,68,69,70,72
www.geocities.com/chevy71tpi/main.html]
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[This message has been edited by Andy4639 (edited April 14, 2002).]