Combining different oil viscosities?

[audirules]

I can't get a straight answer that makes sense to me on this one. Can I put half Mobil 1 0w-40 and half Mobil 1 10w-40 to arrive at my needed 5w-40 for my 2.0 tfsi?.

Most (including a so-called tech guy at Mobil) say no, but can't give a reason that is logical to me. To the best of my limited knowledge, the viscosity range of any one particular oil within the can, is a formula, not a combination of two different weight oils (like a 0 weight plus a 40 weight). Assuming a comparable package of additives and the like, why wouldn't this work?. Thanks for any imput on the matter, as Mobil 1 doesn't market a proper 5w-40 in the US anymore.

 

[Camu Mahubah]

http://www.shellglobalsolutions.teshosting.co.uk/calculations/blending_pop.asp

 

[Turbodriven]

You can use the 0w-40 M1 without a problem, it meets the spec for that motor and it is so close to 5w-40 no1 will ever know the difference anyway. Besides that motor likes that oil, all the samples I have seen within normal useage look good.

As an alternative try Motul Specific or Fuchs

 

[peterr]

Originally Posted By: audirules
I can't get a straight answer that makes sense to me on this one. Can I put half Mobil 1 0w-40 and half Mobil 1 10w-40 to arrive at my needed 5w-40 for my 2.0 tfsi?.


It will not necessarily make a 5w40 but it will be close and it will be fine. It is also not necessary as the M1 0w40 will be just fine, just with a likelihood of better cold flow.

Without being too doctrinaire any application that calls for 5w40 would be well served by a 0w40.

It is this type of confusion that has forced some vendors to sell product that could meet a 0w cold weather spec like 0w20 as 5w20 because people will not buy it since the manual says use 5w20