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a spectral analysis of the base oil confirmed that M1 5W30 does not contain group 4 PAO, and instead contains hydroisomerized group 3 oil, like castrol syntec.
that does not make it a bad oil, it just means you should change your oil 4 times as often as the BMW recommended service, instead of twice as often if you are using synthetic oil.
the problem arises that they did not drop the price or tell anyone, they just changed a bit of the legal wording on their website and bottles in the same manner that castrol did.
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so that means it's time to switch to royal purple ;)
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the reason they switched (other than greed) is because the 5W30 range is by definition low in viscosity range. the synthetic base they were using had a higher range than was required, and instead of fudging with the chemistry to LOWER the VI, they switched to a good high VI GIII base instead.
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Is this also true of the 0-40 M1 that many of us use?
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nope, the 0W40 is full synthetic with a better additive package.
