Mixing different HT/HS oils

[BlueBird]

Its been reported if you mix equal parts of different viscosity oil ( 10w-30 and 10w-40 ) your new viscosity will be something like 10w-35.

Mu question is what if you mix a 10w-30 and a 10w-30 , would the HT/HS numbers of the two oils average out ?

I am thinking Synthetic Maxlife and Synpower or Synthetic Maxlife and Durablend.

Im think that the HT/HS numbers would average out when mixed together.

 

[TallPaul]

Well suppose your 10w30 is 11 cSt and the 10w40 is 14 cSt. Then your 50/50 mix should be roughly 12.5 cSt which is the borderline between a 30 and a 40. As there is not 35 weight defined it would probably be considered a very thick 30 weight. As for HTHS, not sure, but one would expect something at least above the lower of the two HTHS ratings, but I am more reluctant to say average of the two since this is a reading under high load, not just a passive viscosity reading, and in that case maybe the weaker of the two overrules.