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Not to beat a dead horse...

Discussion in '80-Series Tech' started by Seminole, Jul 17, 2003.

  1. Seminole

    Seminole

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    ???I know most are weary of this because of the recent posts but...
    My 91 has 211,000 on it, no leaks and less than 1/2 qt consumption between changes, I want to go to M1(10w-30) for my next change(this weekend), good idea or stupid idea? All my local advice is split 50/50 and 99% aren't cruiser heads, need some sane, expert advice without a dissertation. ANY help or beratement is appreciated.

    'NOLE(praying for an end to summer) 105 with 89%humidity today=@110F
     
  2. semlin

    semlin rocker

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    you are flogging. there are lots of posts on this. Supposedly the synthetics just have a bad rap from when they were first introduced and do not cause leaks as much anymoe. Supposedly. Read the really really long thread on synthetics for more info and check the links. Personally I would do it. I switched to M1 at 122,000 on my 93. 8k later so far no leaks.
     
  3. cary

    cary

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    Mobil 1 10w-30 should be okay, but I worry about your oil pressure being low because Mobil 1 10w-30 is so close to being 10w-20 (9.8cst@100C). :-\ I would suggest that you try and find the Mobil 1 0w-40 given the age of your 80 and the fact that you live in FL. Have you been running a 10w-30 oil? If you have and the oil pressure is okay, go for the M1 in 10w-30. If you have been running heavier oil, and cant find the 0w-40, you may consider the Mobil1 15w-50. I tend to think it is a bit heavy, but if you are only in southern FL, you will never see tempuratures below 50F.

    If all else fails, Pennzoil (which I never thought I would recommend), or Chevron Mineral Oil in 10w-40 should be fine at 4000 mile intervals.

    Cary
     
  4. Seminole

    Seminole

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    ;) Thanks for the replies. I have been running 10w-30 dino, pressure is normal ( 3/4 at speed and right above the 1/4 at warm idle). Actually I am exactly half - way between Tampa and Orlando, we actually do get some low 30's and high twenties in the "winter" but not sustained. I look for M1 0w-40, if not I'll get 10w-30. Thanks again.
     
  5. Hltoppr

    Hltoppr SILVER Star

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    (92, 180,000) If it ain't broke.... I'm sticking with Dino, changing every 3,000 or 3mo. and using the small, good, OEM 20004 filter.

    -H-
     
  6. firetruck41

    firetruck41

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    I've got 185k, switched to synth M1 10w-30 when I bought the LC around 175k, will be changing the oil every 7500. If I can find it I may try the M1 40 weight (5W-40, 0W40?)
    I use the 90914-20004 oil filter as well, twice now the parts guy tells me I can use the cheap YZZB filter instead and asks why I want to pay so much for a filter, but he did order me one when I insisted on the 20004, takes a day to get it.
     
  7. Hltoppr

    Hltoppr SILVER Star

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    Well Ben, can you tell any difference with the synthetic over the dino?

    -H-
     
  8. firetruck41

    firetruck41

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    I haven't noticed any difference, I had dino for the first 3k as the PO had an oil change done the day before I bought it. It consumed oil with the dino, but I didn't have it long enough to really gauge it. Switched to synth and no leaks, it consumes some oil as well, about 2.5 qts over 7500 miles. I'm doing my second oil/filter change today and plan on keeping a record of oil consumption this time around. I don't think consumption has changed, and my oil pressure has been good,same as the dino.
     
  9. Hltoppr

    Hltoppr SILVER Star

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    Keep us posted with what you find. A lot of us have high mileage 80s. I'd be interested to see if you have any gas mileage increases, etc.

    -H-
     
  10. Eduardo96FZJ80

    Eduardo96FZJ80

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    -H-,
    Very good point, on the gas mileage. I myself personaly have always been leary of using synthetics on older vechicles, but am always open for improvement.
     
  11. cary

    cary

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    Milage Increase: I have noticed what appears to be about .5mpg increase since going to 0w-40, it is hard to confirm however since my driving conditions vary a bit.

    Switching to Synthetic: I have switched several cars to synthetic with over 100,000 miles, never a problem. Often I see reduced consumption. My pathfinder has 180,000 miles on M1, no consumtion between changes. Also, you can go synthetic and back to mineral with no problems, it is an old wives tale that you can't. Often people switching to M1 for the first time notice a cleaning effect, probably a stronger additive package.

    Cary
     
  12. yooper

    yooper SILVER Star

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    Syth is just plain better. I got a HUGE cleaning effect when I switched to Mobil 1 at 133K. 2500 miles or so later the oil was BLACK. I use 15W-50 year round up here in the far North and the truck turns over EASIER in the winter than it did with 10W-30 dino oil. Synthetic oil flows much better in the cold than dino oil and the weight ratings are not equivalent for simple viscosity at temperature. I think this is the third time I've posted this this week. Make sure you read the synthetic oil thread and the sludge thread.
     
  13. cary

    cary

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    [quote author=yooper link=board=2;threadid=3749;start=0#msg27784 date=1058575689]
    Syth is just plain better. I got a HUGE cleaning effect when I switched to Mobil 1 at 133K. 2500 miles or so later the oil was BLACK. I use 15W-50 year round up here in the far North and the truck turns over EASIER in the winter than it did with 10W-30 dino oil. Synthetic oil flows much better in the cold than dino oil and the weight ratings are not equivalent for simple viscosity at temperature. I think this is the third time I've posted this this week. Make sure you read the synthetic oil thread and the sludge thread.
    [/quote]

    Yooper,

    I'm sorry but you are simply not correct about the weight ratings being different for synthetics than mineral oils. Synthetics tend to be more temperature stable, but 15w-50 is the same weight if it is mineral or synthetic.
    The 15w part means that the oil must be less than a certain CST at a certain temperature, in the case of 15w it must be less than 6500 cst @ -20C I believe, for 10w it must be less than 6500 cst @ -25C (I know the temps for sure just not the cst breakpoint). I will again as I offered earlier this week be happy to provide the mobil pdf charts that show the viscosity of their oils at all tempurature and you can compare the mineral and synthetics.

    I'm not trying to be jerk, but I don't like seeing inaccurate information posted. There is enought bad info out there already. Please see the below post I made to bob is the oil guy concerning mineral v. synthetic oil properties. Please note that you can not compare the 20w-50 to the 15w-50 because they are not the same weight. You have to compare the 10w-30 formulas because they are the same weight, and you will see there is a difference in cold flow properties but it is not great.

    I just wanted to post some random notes concerning oil viscosity. Mark from NY was kind enought to send me the oil PDF's from Mobil, from which I took Mobil 1 graphs and overlayed a couple of the Mobil clean drive oils (Synthetic v. Mineral). It is interesting when you look at the graphs (Vertical Axis Centistokes in a logrithmic scale, horizontal tempurature also logrithmic) because they are linear. Here is where it gets real intersting:

    1) The mineral 10w-30 runs close in thickness to the M1 10w-30. This is much different than the 20w-50 mineral v. 15w-50 M1 where the M1 15w-50 is far superior in pumpability at low tempuratures (noting of course that these oils are two different weights).

    2) The M1 0w-30 and 5w-30 are so close through their tempurature spectrum that their lines run together. They are pratically the same oil.

    3) M1 0w-40 has a flatter slope than any of the other oils, meaning that it changes thickness the least.

    4) To give a few ideas about the thickness as various points:

    For the oils to be 10,000 cst in thickness the tempurature of the oils is as follows:
    M1 0W-30 & 5W-30 -33F
    M1 0W-40 -30F
    M1 10w-30 -26F
    Mobil Mineral 10w-30 -18F
    M1 15w-50 -15F
    Mobil Mineral 20w-50 7F


    For the oils to be 3000 cst in thickness the tempurature of the oils is as follows:
    M1 0W-30 & 5W-30 -12F
    M1 10w-30 & 0w-40 -7F
    Mobil Mineral 10w-30 0F
    M1 15w-50 8F
    Mobil Mineral 20w-50 24F

    For the oils to be 500 cst in thickness the tempurature of the oils is as follows:
    M1 0W-30 & 5W-30 27F
    M1 0W-40 40F
    M1 10w-30 32F
    Mobil Mineral 10w-30 38F
    M1 15w-50 54F
    Mobil Mineral 20w-50 67F

    And finally for the oils to be 15 cst in thickness the tempurature of the oils is as follows:
    M1 0W-30 & 5W-30 175F
    M1 0W-40 207F
    M1 10w-30 182F
    Mobil Mineral 10w-30 183F
    M1 15w-50 230F
    Mobil Mineral 20w-50 228F


    Take what you will from these numbers, but my view is 1) if you live in cold climate use the M1 0w-30, 5w-30, or 0w-40, 2)Synthetic 15w-50 offers no cold start advantage over mineral 10w-30, but does offer a significant benefit over mineral 20w-50, 3) As you get to operating tempurature (212F) all the 30 weights are the same, the 40 weight is thicker and the the 50 still thicker. Obviously in an extreme situation the Synthetics will withstand higher temperatures than the mineral oils before breaking down.

    For me, I am now using Mobil 0w-40 in all my cars, a 94 BMW 525i, a 91 nissan Pathfinder, and a 96 Toyota landcruiser. I like the idea of the better oil flow at lower tempuratures, but still feel the 30 weight is to thin on the high end.

    Interestingly, my Landcruiser and Pathfinder both call for 10w-30 in warm weather, but overseas they spec 20w-50 for warm weather. The 40 weight gives me a better feeling.
     
  14. yooper

    yooper SILVER Star

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    :eek: Wow. Thanks! I'm not sure how to explain my experience this winter, though. It was a clear difference - it was about -10 F every morning for a couple weeks. In the middle of this period I changed from what I thought was mineral 10w-30 over to Mobil 1 15w-50 and the engine turned over much quicker on cold starts the very next day and thereafter, and was never sluggish for the rest of the winter, including in temps to -25 F or so. I parked it outside every night. :-\ ???

    Whatever! :p

    I probably will go to ow40 for the winter. :)
     
  15. landtoy80

    landtoy80

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    You sure U didn't have 20w50 in it?
    kurt
     
  16. landtank

    landtank SILVER Star

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    Cary man, with the exception of a professional porn star I can't think of anyone more into their lubricants :D :D :D!!!
     
  17. yooper

    yooper SILVER Star

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    [quote author=landtoy80 link=board=2;threadid=3749;start=0#msg27942 date=1058666024]
    You sure U didn't have 20w50 in it?
    kurt
    [/quote]

    I can't be sure, as it is the oil that the PO put in, and it wasn't real old as he had just changed it for the sale and I changed it 6 weeks after buying th truck. He told me that he always used 10W-30, but who knows? There was certainly a big difference in ease of cranking at -10 F.