I ask this question as I plan on using 10W30 motor oil in my Jeep's manual transmission and need no sulphur added to the oil so that it is "yellow metal safe". I'm not looking to start a discussion around whether or not motor oil may be used in manual transmission but rather, looking for information on whether motor oil (synthetic or mineral) contains sulphur as an additive. I assume synthetic does not.

1 Answer 1


Synthetic based oils do not typically contain sulphanates. Mobil, as an example recommend Mobil 1 synthetic gear oil in lieu of a GL-5 lubricant that does contain sulphur and as you correctly state is injurious to copper, brass, and the like.

  • I'm sorry, Mike ... how does this in any way answer the OP's question? Also, when posting an answer, please refrain from using abbreviations and local color. You may know what a g/box is, I can figure it out, but some others may not have a clue. (I know, g/box is an easy one, but I've seen many more you've left behind which has taken me a minute to understand). Remember, as well, punctuation, sentence structure, capitalization and spelling are you friend. Commented Apr 12, 2014 at 18:59
  • point well taken paulster-shall comply
    – mike
    Commented Apr 13, 2014 at 4:37
  • Thanks for the response. So far no really clear answer but I did find thus link to be very useful: widman.biz/uploads/Transaxle_oil.pdf Commented Apr 14, 2014 at 0:48

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