Mixing oil viscosity
10-07-2015, 07:28 PM
#1
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Mixing oil viscosity
Is there any harm in topping up with 0W40 if my last oil change used 5W50 - or visa versa? Mobil1 in both cases.
DaveGee
DaveGee
10-07-2015, 08:33 PM
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10-07-2015, 09:25 PM
#4
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some will argue that different oil brands have different additives and if its an unlucky combination it will have an adverse effect (though i am not sure exactly what that would be)... i dunno, but i have heard it preached, especially on the air cooled boards - i suggested mixing two mobil synthetics once on the 993 board and people there were saying 'no no no you stupid fool'...well, whatever...
it would make sense that within a same oil brand it would be just fine... i suppose that base oils are blended at the refinery to make the multi weights we buy anyway...
it would make sense that within a same oil brand it would be just fine... i suppose that base oils are blended at the refinery to make the multi weights we buy anyway...
10-08-2015, 07:38 AM
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Mixing Mobil synthetic with Mobil synthetic is fine. Purposely mixing Mobil with Motul, as an example, is not good.
It's all about the additive packages. Some are Ok with each other. Some fight each other. That's why, for example, Jake Raby of Flat Six Innovations, recommends an oil flush process when using his Driven Joe Gibbs DT 40. DT40 really fights with Mobil. I've seen the UOAs first hand. This is also supported by Lake Speed, the oil guru at Gibbs.
It's safe to assume the additive packages within the same brand are most compatible. Doing a cross brand mixology might not work so well for the additives.
It's all about the additive packages. Some are Ok with each other. Some fight each other. That's why, for example, Jake Raby of Flat Six Innovations, recommends an oil flush process when using his Driven Joe Gibbs DT 40. DT40 really fights with Mobil. I've seen the UOAs first hand. This is also supported by Lake Speed, the oil guru at Gibbs.
It's safe to assume the additive packages within the same brand are most compatible. Doing a cross brand mixology might not work so well for the additives.
10-08-2015, 09:10 AM
#6
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Yes but why do it? Just get some more of what ever brand & viscosity you have in it then top it off (or leave slightly low as recommended -don't overfill)! Or do an oil change. I run 5/40 if the majority of my future driving is in warm wx months & 0/40 if in colder months. But always same brand. Porsche recommends Mobil1 but other's swear by Motul. Choices are nice!
