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Gear head said not to use synthetic in diffs and this is why!!

Discussion in 'Maintenance & Upkeep' started by the phantom, Aug 7, 2012.

  1. Marcus A.

    Marcus A. Rockstar

    guess I'm just a little obsessive compulsive
  2. stchman

    stchman Active Member 1 Year 1000 Posts

    IIRC, GM part # for lubricant in the differential is synthetic. Also, GM does not have an interval for fluid change in the differential.
  3. elkhornsun

    elkhornsun Member

    Whatever experiences the mechanic has in the 1980's or 1990's or even over the last 10 years should not be used to decide what to do with a new vehicle. Metals and lubricants have changed over the last 30 years. Used to be that motor oil was changed every 3k miles but now it is common to go 15k miles.

    With a differential and in particular one with a locker or a limited slip I would go with the manufacturer's recommendations as to the lubricant to use and the change interval. I doubt the majority of owners perform regular maintenance on their vehicles and the differentials that the mechanic has seen over the years are likely to be ones where neglect was a factor in their early demise.
  4. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    Conventional lubricants are outdated tech from the 19th 20th century and really have no use in the 21st century. Good synthetics like Amsoil are 21st century tech. Would you use 20th century PC tech in the 21st century? No...If you did you most likely would not be on this forum right now.
  5. Skippy

    Skippy Member 2 Years 100 Posts

    I wish it were completely black and white like this. Unfortunately, quite often conventional lubricants from 20, 30 and even 50 years ago are more than completely adequate for the job they perform. YES, Amsoil and other lubricants are superior in just about every way, but when a vehicle calls for conventional lubricants, that typically means the lubricants are more than capable of performing according to the manufacturer's specifications.

    This is NOT to say I'm not a proponent of synthetics, I am. I'm just leary of blanket statements discounting "old tech" that is more than capable of protecting the engine according to manufacturer's specifications.

    I often giggle at how often conventional oil folks change their oil (every 2K or 3K), when the oil (conventional) is far more than capable of performing exactly the way it's intended to for an additional 2-7K Miles. Then I realize I'm the guy who replaces his Mobil 1 every year, in spite of the fact I only drive my vehicle's about 2500 miles each. I'm just as bad as the rest of them. Is there something wrong with the oil? Nope. And quite frankly, conventional would provide me the same protection in that time frame under those miles.

    YES... Synthetics will wear better and longer, but quite frankly, our "conventional" oil engines ALSO run quite well on conventional.

    Short end of the stick: Nothing wrong with conventionals as long as you know the application fits the bill.

    Cheers.
    -Skippy
  6. TimTom64b

    TimTom64b Member 2 Years 500 Posts ROTM Winner Gold Member

    I'm sticking with synthetic oils... conventional oils can not withstand higher temps and breaks down faster. My guess is if you are getting build up in the differentials you are not changing your fluids enough.
    Last edited: Feb 17, 2013
  7. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    My point is that synthetics will do a better job. And yes there a few applications in older equipment where synthetics can't be used due to materials.

    A note on your oil changes. Even if you only put 2500 miles on a year it is still good to change it as moisture and settling contaminates need to be removed.

    Tip. When is the best time to change lubricants on things that get stored?
    A: Before putting them into storage.
  8. elkhornsun

    elkhornsun Member

    Some of this reads like the fat people who when asked why they smoke reply that if they quit they would gain weight. Synthetics have their place but no fleet operators with trucks putting on millions of miles each year are 100% synthetic with their trucks and these each represent a $200k or better investment. They run their operations like a business though and will not put in synthetics simply based on the advertisements in the truck and car magazines with some babe in tight shorts or some racer who is paid hansomely to use STP or some other additive - at least until they stop winning races.

    If the SAE (society of automotive engineers) lubricating specifications are met that is all that is important to the engine. It does not know you are putting cheaper dino fluid or something that cost over $40 a gallon and it does not care. No harm in using synthetics any more than flooring it every time you leave a stop light - it is your money you are choosing to waste.
  9. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    I would have to say different. Synthetics will give you better fuel mileage and also protect better thus creating longer engine life diesel or gas.

    Some things to read:

    www.amsoil.com/lit/g2860.pdf
    www.amsoil.com/lit/g3086.pdf
  10. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    I must agree, that synthetics have an advantage over conventional.

    The high mileage fleet owner may not need synthetic oil, his trucks are always running, the oil is always hot.

    If you live in the colder parts of the world, a cold morning start with conventional oil can reduce the live of your engine. Thick cold oil will not flow like cold synthetic oil.

    I use synthetic for only one reason..........cold morning starts; the starter spins the cold engine like a warm engine and I know the pump is able to move the cold synthetic easier than the cold conventional.

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