Quote:
Originally Posted by E-Money
So it sounds like the OP is doing the right thing by mixing in 0W-40? I also use Mobile 1 for track days but I'm 100% 0W-20.
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Adding in 0W40 will slightly bump up the viscosity, the High Temp High Shear, the detergent levels, and the anti-wear additives.
Whether or not it is helpful or detrimental over the long term is another debate. Many people have been mixing oil for years while others say that it shouldn't be done on a regular basis since the two oils were not engineered to work together and you are affecting the cold cranking viscosity by mixing. Of course, cold cranking viscosity is not so important during track season though.
"Shannow" on bob is the oil guy is very much against mixing oils:
http://www.bobistheoilguy.com/forums...for_Oil_Change?
Unlike many people there, he usually provides data for his statements instead of just expressing an opinion. His experience is in the design of bearings. This might really be splitting hairs if you're doing short-ish runs on the oil, but you can read that link and make your own decision.
And if you think by using something like regular Mobil1 5W-30 or 0W30 you'd be bumping up your viscosity, these oils actually shear to a 20 grade under hard use so you do not necessarily end up with a thicker viscosity (although you
do get more ZDDP). If you're concerned about wear and protection, I would at least run Mobil1 5W20 or Mobil1 0W20 EP over M1 0W20 AFE due to the higher ZDDP in those as well. Or perhaps Mobil1 xW30 for the additional ZDDP and
maybe a slight bump in operational viscosity.
M1 ZDDP info here:
https://mobiloil.com/~/media/amer/us...ecs-guide.ashx
This site provides a viscosity calculator for mixing oils so if you really want to get to a precise viscosity:
http://www.widman.biz/English/Calculators/Mixtures.html
Some oil companies say that it's fine to mix their oils if you're mixing oils within the same family (e.g. Mobil1 AFE, Mobil1 EP, Red Line street oil, etc.). I don't recall if XOM said that, but it's probably best to contact the manufacturer for their opinion.