10W-30 or 5W-30 in a 2003 5.3?

Discussion in 'GM Powertrain' started by ibmoses, Mar 21, 2009.

  1. ibmoses

    ibmoses Rockstar 100 Posts

    The dealer serviced this truck(03 2WD Silverado 5.3) until the extended warranty expired at 5 years...since then I have been using 10W-30 conventional oil.

    GM recommends 5W-30 and I assume that is what the dealer was using but never even checked.

    It gets very hot here in North Alabama and even in the winter the temp does not get below 15* very often for very long...

    I am thinking 10W- 30 is fine but am looking for some reassurance. What do youse guys who live in the hotter climates use?


  2. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    If you do not get cold weather it really does not matter between 5W-30 and 10W30. They are both 30 weight oils. My money is on the dealer using the 5W that is what most gm trucks run. The 5W will get better mileage until the engine coms up to temp.Read the following for an explanation of viscosity:

    When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Coldertemperature. The numbers without the are all tested at 210° F or 100° C which is considered an approximation of engine operating temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210° (100° C). The difference is when the viscosity is tested at a much colder temperature. For example, a 5W-30 motor oil performs like a SAE 5 motor oil would perform at the cold temperature specified, but still has the SAE 30 viscosity at 210° F (100° C) which is engine operating temperature. This allows the engine to get quick oil flow when it is started cold verses dry running until lubricant either warms up sufficiently or is finally forced through the engine oil system. The advantages of a low W viscosity number is obvious. The quicker the oil flows cold, the less dry running. Less dry running means much less engine wear.
  3. 178kchevy

    178kchevy Member

    I agree with Scott, It probably doesn't matter which you use, but, I know that the manufacturers are recommending 5W30 for the newer engines. I had to have a remanufactured motor put into my truck a couple of years ago and I run 5W30 in it.

  4. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    They all go with the 5W it seem like due to mileage. We all know that every year it seems like new laws go into effect for the manufactures. And the lower the viscosity the better mileage you will get.
  5. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Living here in Ohio with the hot summers and cold winters, I use 10W-30 in the winter time and 5W-30 in the summer time. I do this on my dad's 6.0, and my 5.3 for the last 5 years and it has worked okay for us.:great:
  6. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    I think you have those backwards. It should be 5W in the winter and 10W in the summer. Think of the W as meaning winter.
  7. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Oops! That is why I shouldn't be on here at 1:00 in the morning! :lol:
  8. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    If you do lots of short trips, the 5w might be better-less wear over time-since it will get to where it needs to be a tiny bit quicker.
    Long high speed highway stuff and towing- 10W might be better because a 10w might have fewer viscosity modifying molecules and more pure lubricating molecules. Probably a pretty tiny difference either way.

    You'll probably do just fine either way.
  9. mrcheek

    mrcheek New Member

    I run 10W-30 which the manual says is OK for my climate zone. Of course our average temp is 70 and it never gets below 20 for any significant amount of time. If you have consistantly cold (I mean like BBBRRRRR!!!) use the lower viscosity until the weather warms the you have a choice if cost is a factor.

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