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Old 01-25-2010, 05:43 PM
advertisehere advertisehere is offline
Location: Belmont, CA
Join Date: Dec 2009
Posts: 72
Mein Auto: '96 328i sedan
I emailed bimmerworld:
Why would a different viscosity be recommended for different climates (like 5w40 for cold and 10w40 for everything else)? I understand that a 5W is necessary for cold starts in cold climates, but I dont understand why a 0W wouldn't be better in all climates since a cold oil is inherently too thick no matter how many viscosity improvers are added and at temperature the viscosity is effectively the same for a 0W40 or 15W40. Also, since most engine wear occurs when the engine is cold, wouldn't it be more beneficial to use 0W30 instead of 0W40 to get better lubrication?
By the way, I have an M52, which is why is used those as examples. And my info came from here if you're interested in spending the time reading.

Thanks for your time,
and got this:

To get the best answers to your questions I would suggest calling Red Line Lubricants directly considering their abundant knowledge and decades of experience.

Our local BMW dealer uses 15W40 oil for the M52 engine and 5W30 for the later M52TU engines. These viscosities are approved by BMW and will work fine for most drivers in a majority of climates. BMW has never suggested a 0W-XX oil for any application I am aware. As a Red Line dealer, we consulted with them and their decades of knowledge to give better options for our customers based on their climate and use. These viscosities are what Red Line and BimmerWorld agree are the best viscosities for a given climate and condition.

Oil lubrication properties can be argued and discussed for hours on end and have been for decades, especially on public automotive forums. I'm sure the forum you've provided has some interesting insights to lubrication but we base our knowledge on decades of Red Line oil development and BimmerWorld's accumulated knowledge and racing.

If you adhere to our advised viscosities and oil change intervals your engine will last as long as BMW intended and there will be much less time spent on public forums and more time driving!


Brian Fowler

Race Proven BMW Performance

So I called Red Line, which i probably should've done earlier, and found out some interesting information. Basically, Dave said that he wouldn't bother running a 0w40 instead of a 10w40 unless he was really concerned with the cold running properties of the oil, not to mention that there is only about an 8% reduction in viscosity at 40C for the 0w compared to the 10w. Plus the 10w40 doesn't have any VIIs, although he said theirs don't have shearing issues so it doesn't make too much of a difference.
I then asked about a 0w30 and he said that would be reasonable, although there might be some sacrifice in protection under high load (I think that might have to do with oil pressure at high engine speeds but I didn't ask.). And since the vast majority of my driving occurs in trips that last less than 30 minutes, I think the 0w30 will probably be my best choice in the future.
He also mentioned dealers putting in 5w30 for cars where the recommendation calls for a 40 with no problems arising. (not exactly in those words)

I have a couple more questions though, so I'll probably call again tomorrow.

And here's the product info sheet:

Last edited by advertisehere; 01-25-2010 at 05:46 PM.
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