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Synthetic Oil! 0-40, 5-40, 10-40

2008 Jetta S 2.5 , VW 502 oil specs are met by Moble1 synth 0-40W, 5-40W, 10-40W.

Back in the day of one weight oil, the standard philosophy was the hotter the driving conditions the heavier the oil used. End of problem.

My question (which I've had since synth came out) is now with these multi viscosities does the same philosophy apply? Do I use 10-40W because I live and drive in Florida? or is 0-40W still OK in Florida?



  • It's the greatest mystery of the New Baloneyum. I haven't read the latest Nicene Creed of oil so I wouldn't even try to answer the question. Kind of like the people we elected to counter the president we also elected. Why do we do that?
  • Ha! Like it,
    Tnx for the comment.
  • When looking at multi-viscosity oils ie: 5W-30, the first number, 5W is the winter weight of the oil. This is the viscosity of the oil when the engine is cold so that the engine is provided with lubrication is soon as possible when it's started. Once the engine reaches operating temperature the oil has the viscosity of a 30 weight oil.

    So you can use a 0W-40 oil if you want. It just means the oil will flow faster on a cold start than a 10W-40 oil. But both will have the viscosty of a 40 weight oil once the engine reaches operating temperature.

  • OK, good info. But, It is rarely cold here in FL. Would my engine be better protected with the 10-40W as apposed to the 0-40W ?
  • I would have purchased 10-40W based on this/ my understanding but typically difficult to find the 5 or 10-40W. So I purchase what I can at the time I have available to change. Also, when on sale at Auto Parts, with filter.
  • ... Moble1 synth 0-40W, 5-40W, 10-40W
    The 10W-40 grade is intended for those who live in tropical or semi-tropical climates. The other grades are also acceptable for Florida residents.

  • Does you owners manual have anything to say about this? Some have a diagram with a temperature range and the different viscosity recommended.
  • Mobil 1 10-40 is not VW 502 approved .

    Here's a list of oils that meet that spec .

  • Genex, your list is for the GTI, which has that nifty turbo. The OP is driving the tamer Jetta.

  • Google "Viscosity Index Improver" and how they work to understand what is going on here...
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