Oil changes?

Discussion in 'General Automotive Tech' started by AshTray900, Nov 8, 2022.

  1. AshTray900

    AshTray900 Well-Known Member

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    So I read a lot of stuff saying you should change motor oil after time if mileage remains low, I guess this is probably true to an extent but I’m wondering how valid this 6 months to a year is. I know we kept going with the 3000 mile interval years ago and it wasn’t really needed that frequently so I have questions here that maybe a mechanic can give an honest opinion on. I’m a good home mechanic and have rebuilt several broken down cars back up, however I’m not an oil specialist.

    so all I use is mobile one full synthetic in any car. The oil has been sitting in my wagon for almost 4 years. I also have two Hondas both have oil in them about 1 and a half years. We aren’t hitting mileage requirements for oil changes on any of our cars. Pulled all 3 dipsticks, all three exactly the same, golden brown like the day they were poured in, smooth and slippery to the touch just like new, absolutely no visible contamination.

    the Honda service department told me that their oil is mobile one full synthetic for all their cars and the oil life meter is supposed to monitor time as well and their is no need at all to bring them in before the maintenance light comes on. One of the Hondas says it has 80% oil life left on oil over a year old.

    so the real question here is does this high priced oil actually need changed after a friggin year? The wagon is loving the oil after 4 years and it still looks brand new and feels good. The car runs perfect, doesn’t overheat, no signs of any oil time degradation.
     
  2. OldFox

    OldFox Curmudgeon

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    There are many variables. It depends on the car. If it has a flat tappet cam and a carb, then it should be changed every 90 days or 3000, whichever comes first.
    75% of engine wear occurs during start-up and warm-up. Everything is dry, the oil will suffer from gas dilution and condensation if only driven for short trips. It takes a while for cold oil to lubricate all the critical parts. Oil for these cars require an additive to prevent galling of the cam lobes, which will occur if modern oil is used in these cars. It lacks the additive.

    Newer cars with roller tappets have less friction and don't need it. Also, they use very thin oil which gives almost instant lubrication on start-up. Our Toyota uses 0w16 weight oil. The electonic fuel injection controls the gas dilution and the crankcase ventilation is more efficient at controlling condensation. Cars that are driven the most usually last longer because they always get up to operating temperature which is the most efficient.

    Cars in cold northern states are more prone to engine wear and less so in warmer states. It is not unusual for today's engines to last 300K whereas older cars were lucky to make it to 100K.
     
  3. AshTray900

    AshTray900 Well-Known Member

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    Ok while my wagon may be an antique car now, it’s engine is modern compared to most, a motor style used up past the year 2000, it’s a 96 Buick with a 3100, injected well sealed up, not alot of places for air to get in besides a closed throttle, that’s probably why the oil is still in such good condition after a few years, I may be wrong that oil may only be 2 yrs old, hard to remember
     
  4. Doghead

    Doghead Well-Known Member

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    You're probably not doing alot of stop and go driving, then. That in itself will cause plenty of wear and blacken the oil.
    I've heard that oil has a shelf life. But if no date is printed onto the bottle, what's to say that stores will take old oil off of their shelves?
     

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