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  • #16
    Re: oil change interval

    I don't think the correct standard is 'could possibly be tied to.' If there is enough oil and it has it's lubricating properties intact (easy to test for), oil would be unlikely to be the direct cause of an engine problem regardless of time or miles.
    02 GX
    01 GX
    03 Crown Vic
    06 GX
    Home Fueler

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    • #17
      Re: oil change interval

      I went back through the recent posts in this thread. I see three points that have been missed.
      First the contaminants that accumilate in the oil, Yes, NG is low carbon and has more complete combustion and that reduces some comtamination. There is still the problem of contaminants from normal engine wear an operation; analysis can help identify those levels and act as a guide to oil change intervals.

      Second is thermal break down of the oil molecular bonds (that is the film thickness that keeps part separated). If you putt-putt around town it's less of a problem. However, the smaller displacement engines, by the their nature work harder, raising the oil temperature, and accelerating thermal break down. Synthetics are great when it comes to thermal break down so you can go longer between changes. Where is limit on theremal break down?

      Third, oil will tend to thicken in a gaseous fuel engine (NG, LP, H2) since there is not un-combusted liquid fuel to dilute the oil. If you have noticed, there is a movement to "thinner", less viscous, oils. (look at the hybrids that use a 0W-20 or my CRV that uses 5W-20). With the tighter clearances in modern engines it is extrerely important that the oil not be too thick; especially on start-up.

      The only to cure these problem is to change the oil and filter

      With an eye to engine life, and I've had several vehicle that have over 200K miles. I change oil often depending on the type of driving I'm doing and I do use sythetic. Warrante is a consideration. I usually change sooner than the recommendations, but that is my preference. I also keep in mind what I was told by my community college Diesel instructor; "... grease and oil and cheap compared to engine parts".

      Larrycng
      Last edited by larrycng; 12-16-2010, 09:25 AM. Reason: forgot something

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      • #18
        Re: oil change interval

        I agree in theory. I have one vehicle over 200k and two most of the way there. I was concerned about thermal breakdown and excessive wear, too, which is why I tested the oil after 15k miles in the GX. And I'm in southern cal which should be pretty tough on oil in the summertime. The oil met all the 'new' standards and no signs of unusual engine wear. So, while theoretically the oil could break down under these conditions, it doesn't to any measurable degree. And this is with WalMart oil, not a fancy synthetic or even a brand name. If you change the oil 4x/year with synthetic vs 1x/year with SuperTech the cost difference becomes significant, especially with a small 'fleet' like I have.
        02 GX
        01 GX
        03 Crown Vic
        06 GX
        Home Fueler

        Comment

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