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When should i switch from conventional to synthetic...

Discussion in 'The Garage' started by dirtwarrior17, Aug 5, 2005.

  1. dirtwarrior17

    dirtwarrior17 Banned

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    oil on a new motor? The builder told me to take it easy on it then change the oil at 500 miles. Can i switch to synthetic at 500 miles or do i need to wait?

    If so when can run synthetic?
     
  2. R72K5

    R72K5 Banned

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    i have same Q because the 350 in the 80 c-20 i am getting has 1300 miles on it after total rebuild, bearings rings and all,

    i wonder the same thing about what oil to run,

    maybe some mobil 1 ?

    thanks
     
  3. Robert79K5

    Robert79K5 1/2 ton status

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    I put synthetic in my 355 right after the initial break-in oil change. I built that engine eight years ago and its been in two trucks. Some engines come from the factory with synthetic in them so I wouldn't worry about putting it in too soon.

    Iv heard people say that synthetic is too slippery and that you should break the engine in on fossil base oil then switch to synthetic, but I beleave thats just crazy if you break it in right.
    But thats just what I personally believe so YMMV
     
  4. HarryH3

    HarryH3 1 ton status Author

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    It depends on the rings that were used. Moly rings are HARD and take much longer to wear to match the cylinder walls. I've read that synthetic oil can prevent that from happening. Iron rings will seat much quicker.

    Also, your local machine shop doesn't have the resources that General Motors has when it comes to assembling a close tolerance engine. So expect that the clearances won't be nearly as close as in a brand new Corvette.
     
  5. coptezr

    coptezr 1/2 ton status

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    when i put my first 500 miles on my motor then i put synthetic in.
     
  6. Eric M.

    Eric M. 1/2 ton status

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    I was always under the impression that Synthetic would last longer and withstand higher operating temps. (like racing applications) before breaking down. I never heard that is was "more slippery". I was told you could go 10K miles between oil changes without fear of breakdown. BUT, in daily driving situations, you'd want to stick to 3K to 5K because the oil gets dirty / comtaminated even with the best of filters way before 10K and dirty Synthetic isn't any better than dirty fossil based oil.

    Eric M.
     
  7. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    I thought it was the other way around. Moly rings are somewhat pourous and have better oil retention, better resistance to higher temperatures and therefor seat much quicker, but require a carefull break-in. Plain cast rings take alot longer to seat, you don't have to be as careful, but it will burn a little oil until they are seated which is usally several thousand miles. Moly rings seat much quicker, 500-1000mi.
    Chrome rings are very hard, take a long time to seat but are great for high containmnent envoironments due to thier hardness and resistance to holding on to contaminents.

    Reference:


    http://www.hastingsmfg.com/Service%20Tips/ring_set_composition_recommendat.htm
     
  8. Mad-Dog

    Mad-Dog 1/2 ton status

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    After the rings are seated.........
     
  9. dirtwarrior17

    dirtwarrior17 Banned

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    does 500 miles sound right for moly rings? The block is an lt1.
     
  10. Mad-Dog

    Mad-Dog 1/2 ton status

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    mileage may vary, a good sign the rings are seated is a reduction in blowby.
    new motors tend to have excessive blowby until the rings are seated.....
     

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