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8100 Vortec 5W30 only?

Discussion in 'GM Powertrain' started by 572ysc, Jul 29, 2008.

  1. 572ysc

    572ysc New Member

    So I was reading up the onwers manual about doing an oil change on the 8100 Vortec engine and they state that never use 10W40 or 20W50 wheight oil. Does somebody know what the cause of this is? I know many manufactors don't recommend this kind of wheight due to in winter or in cold conditions the oil is to heavy. But this manual states the big no at all conditions. Will it hurt the engine? Has someone tried it and had bad luck? Im guessing right off now that due to it beeing a tall deck motor the engine oil takes too long to go up to the lifters and so and that due to this there is wear of the valvetrain and cam,.. am i correct?
  2. gbear

    gbear New Member

    Many new engines are built with smaller oil galleries and with a thicker oil you may not keep the same oil pressure as your engine needs, as well ass your mileage may decrease.
  3. retired2001

    retired2001 Epic Member 5+ Years 5000 Posts

    I agree with "gbear" about the tighter tolerances. The lower visc. is also designed to give better fuel mileage, due to lowering friction. I went up on my last trucdk and lost a from a half to one mpg, so Ii went back to the thinner visc. Good luck and Happy New Year!
  4. silveradojc

    silveradojc Former Member

    10/30 synthetic in mine with no problems 101,000 miles
  5. Jacqson

    Jacqson Rockstar 100 Posts


    I've been using Redline 10W-40 in my 6.0 for years and have never noticed a decrease in gas mileage. It actually runs a lot better and also helped with the CSK.

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