which kind of oil to use on a 1993 gmc sierra v8 5.7L 350?

its got about 168,000 miles on it, i was was thinkin castrol gtx oil maybe? what about any synthetic oil? thanks!

7 Answers

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  • Anonymous
    1 decade ago
    Favorite Answer

    5w30 or 10w30 is fine. With an additive like lucas, stp or duralube.With mileage like that,synthetic can cause major oil leaks if the engine hasnt had synthetic from new.

    Source(s): 25 years + ASE master tech
  • 1 decade ago

    no synthetic ! ! ! ! !

    You can get some high mileage oil

    or

    even a can of lucas oil stablizer - extender.

    But as far as switching to a synthetic - no - there really is nothing better than regular oil, and your old 5.7 tbi 350 will not do any better!

    I suggest 5W-30 regular engine oil, along with a tugg guard oil filter, and twice a year add a bottle of lucas oil treatment to it !!!!

    Source(s): ASE master tech Those engine are good for 300,000 + if they are treated right !!!
  • 1 decade ago

    I would definitely use an oil that is designed for older engines. Usually a synthetic one.

  • 1 decade ago

    conventional 5w30 is fine but i reccommend the use of lucas oil stabilizer used as directed to improve viscosity and improve oil consumption. do that and watch your oil pressure go up a bunch

    Source(s): im a mechanic and I have a 95 z71 gmc
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  • hilma
    Lv 4
    3 years ago

    Whenever i post a question, even if its the easiest one, they cant provide me a proper informed answer on this website. what happened to people who actually take the time to write an answer??

  • 3 years ago

    Great point, I'd like to know more as well

  • ken k
    Lv 7
    1 decade ago

    wuse whatever got you to 168000 miles

    Source(s): mech
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