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  1. #1

    Default Synthetic or regular motor oil

    I have a 2001 suburban 2wd 1500 with 217k miles on it. Should I start using the synthetic oil to help with it's performance or stay with regular?
    :sign0021:2001 Suburban 1500 2WD :cool:

  2. #2


    With that kind of mileage stay with regular oil.

  3. #3


    If it's always had regular, stick with it. Synthetic has been known to leak if used on older motors that have never seen it before... I know. I had a perfect T100 with 170k on it on regular oil... changed to synthetic for the mileage benefits and to get it to last even longer, and ended up with a puddle on the driveway... leaks didn't stop even after I changed back to regular. Rebuild wasn't too far after.

  4. #4
    Sr. Apprentice
    Join Date
    Jan 2009
    West By God Virginia!


    I would do the switch to Mobil 1. BUT, and it is a big BUT, it will clean all the gunk from inside the engine. I just switched to M1 in the Mercedes with almost 300,000 miles on it. What you should do is change the oil and filter at 3000 miles and then change it again at 3000 miles. After that you can extend the interval. You can also have the oil analyzed at Blackstone labs to see how much life is left in it.

    If you get any leaks, don't worry about them. The leaks are caused by the gunk being cleaned away from the gaskets. The gaskets will swell with synthetic stopping the leak after a while.

    Didn't the 2001 come with M1 from the factory? My 1999 did. It says fill only with Mobil 1 on the oil filler just like my '96 Impala SS had.
    I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy

    The Herd:
    FoxyCleopatra '99 Chevy Suburban 159K mi
    Rudolf ‘86 Mercedes Benz 300SDL - 305+K mi
    Fritzie ‘84 BMW 528e 234k mi
    Jenny '74 Jeep CJ5 23000 mi Factory plow package

    Former GM cars:
    1957 Nomad 283 4bbl rams horns,glasspacks disc brakes White over red
    1963 Corvair Monza 102hp convertible Aqua
    1963 Catalina 2dr 421 4bbl Navy/light blue
    1967 GTO 400 HO his/hers convertible White over red
    1971 Buick GS 455 Conv Black over red
    1977 Impala 305 2bbl Red/red
    1982 Celebrity Silver /blue 2.8 six
    1988 Corsica Red/red 2.8 six
    1996 Impala SS BBB/ gray LT1

  5. #5


    I agree that Synthetic will basically "flush" the engine. That can sometimes be bad as well... loosening up gunk. I've read that when changing to synthetic, its not a bad idea to do another change only 1000 miles after.

    I disagree with the leaks stopping... mine only got worse. I changed at 1k miles, then every 3k, adding quart after quart of synthetic due to the new leaks that appeared, until I finally tore her down 15k after switching to Mobil 1 syn... wouldn't have had to if I had stayed with dino oil, i'm sure of it.

    I'm a TRUE believer on synthetic from day one or switching on lower mileage vehicles, however. I had an explorer that had synthetic amsoil in every possible place from day one... I sold it with over 300k with the original motor, trans, transfer case, front and rear ends... and that vehicle was worked hard.
    Last edited by jchambers849; 01-18-2009 at 07:53 PM.

  6. #6
    Jr. Mechanic
    Join Date
    Jan 2009
    Elizabeth City, NC


    I agree that it might cause a leak, but if you want to extend the life of your motor I would switch to synthetic. you might have to replace your valve cover gaskets and oil pan gaskets and maybe the rear main seal, but in the end it would be worth it. Your rings and bearings will reap the benefit.

  7. #7

    Join Date
    Feb 2008
    Red Wing, Minnesota, United States


    I woudlnt do it with that high of mileage, but if you do your first run on the synthetic should NOT be more then 1000 miles, the synthetic will break down all the gunk and it needs to get out of there quickly. This is the way the dealerships do it as well, very low miles on the first run of synthetic
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual

  8. #8


    What is considered “High Mileage”? Is it too late to make the change on my 2001 w/ 90K?

  9. #9

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    I bought my 1998 2wd about 20 months ago with 195,000 miles on it.I use Mobil 1 5w30 in both vehicles- no problems-at 208,000 miles now..

    The "leaks from switching to synthetic" might be a holdover from the early synthetics.One early synthetic-it was called something or other Graphite?? Graftex?? I really can't remember the exact name, but it was soooo thin that it leaked from every seal.Even worse it had graphite suspended in it, so the leaky oil was this jet black stuff-really a nasty mess.

    I haven't had any leak problems, but I do use one quart per 3000 miles. This seems about right for a 208,000 miles motor,so I don't worry about it.

    In truth it probably won't matter one way or the other since most of its life has been on standard oil.Regular oil is pretty good now.If it was 100,000 or less I would switch for sure.

    1998 suburban-
    1/2 ton

    199500 miles

  10. #10


    Thanks everyone for the feed back
    :sign0021:2001 Suburban 1500 2WD :cool:

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