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02-03-2009, 05:50 PM
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#1 |
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Registered User
Join Date: Oct 2008
Location: Bozeman Montana
Posts: 21
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Oil Question?
I just bought a 1971 c20 with a factory 400, 83,000 original miles. Does it matter if I use 10w-30, 5w-30, or 10w-40? I had a 1970 with a 350 and I always used 10w-30. Just wondering if it makes much of a difference?
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02-03-2009, 07:10 PM
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#2 |
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All stock and staying that way
 
Join Date: Jul 2003
Location: Elkland, PA
Posts: 1,278
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Re: Oil Question?
I would use a quality 10w30 oil with a bottle of GM EOS to provide your engine critical zinc that is no longer provided in regular oils. The zinc is critical in engines using flat tappet cams and regular rocker arms.
I personally use Shell Rotella 15w40 diesel oil in my '72 402. The diesel oils still have decent amounts of zinc.
__________________
1970 K/5 Blazer CST 4WD, Bronze, 93k ACT. miles, 350, 4 speed, positraction, 16.5" x 8.25" wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration in progress...  1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor...  2017 Sierra 1500 SLT 4WD, Black, 41k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 60k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
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02-03-2009, 07:39 PM
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#3 |
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Active Member
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: Oil Question?
Since you're in cold country, I'd almost go with 5W 30 for the winter. But it all depends on the condition of your engine.
Remember that on these engines 83,000 miles was considered high mileage unless they were overhauled. Doesn't mean that they were scrap but usually at 50K to 60K the bearings, rings and valve guides might loosen up enough to require a higher weight. Here in Texas where the weather is pretty mild, I stick to 10w30 oil for most use and go up to 20w 40 if the engine is high mileage. |
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02-03-2009, 08:08 PM
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#4 |
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Registered User
Join Date: Jul 2007
Location: Salina, Kansas
Posts: 1,998
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Re: Oil Question?
i run castrol gtx 10w30 in all my vehicles
__________________
1972 C-10...402/400..flowmaster 40 series 1967 Mustang 347 stroker/C-4 1966 Mustang 289/3-speed 2013 Mustang V6/6speed w/300 ponies I may be 23, but i sure do knows 67-72s are sexy! Its not MPG its smiles per gallon! build started 11/25/08 build thread: http://67-72chevytrucks.com/vboard/s....php?p=2993796 |
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02-03-2009, 08:16 PM
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#5 |
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Registered User
Join Date: Jun 2008
Location: South Florida
Posts: 11,375
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Re: Oil Question?
cold climate 10w40
hot climate 5w30 that is what we do
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Get your facts first, and then you can distort them as much as you please!!!!!. Sylvester's build thread >>>http://67-72chevytrucks.com/vboard/s...ht=big+rebuild |
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02-03-2009, 10:31 PM
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#6 |
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Registered User
Join Date: Feb 2008
Location: Grande Prairie Alberta
Posts: 261
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Re: Oil Question?
i let the weather decide what weight im gonna use, seeings how your in montana and we are in the beginning of febuary, i would run 5w-30. im not really an expert on high milage stuff but i know when it comes to climate, u gotta up here in Canada. 5w in cold weather makes it easier for your starter to turn your engine compared to 10w oils. other then that theres no difference, but like i said im not an expert on high milage engines.
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eh  1970 Chevy C20 daily driver  1975 GMC Jimmy 4x4 project  1966 GMC C10 Dad's project 
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02-05-2009, 05:47 PM
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#7 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Oil Question?
don't pour in the whole bottole of EOS on one oil chainge, that is way too much. 1/4 bottle is plenty.
Pretty much all the diesel oils now have LESS zink than the gas oils do, so no point in that. |
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