I read a lot and post infrequently but this is a topic that I can't quite wrap my head around and perhaps the answer is obvious and I just don't see it.
I'm going to use PP 5/30 as an example but any other oil in the same grade with a 9 range cSt would be similar, I think.
We know that that shearing and dilution decrease the viscosity and Pennzoil, like the the others, routinely say their oil is resistant to shearing and stays in grade but they don't know what vehicle the oil is going on. If you have a diluter, such as certain Honda's, the oil is going to thin out without question.
If I run a recommended interval of say 5 -10k, the oil will shear or be diluted to a degree and my concern is that a thin 30 will end up as a thick 20 somewhere along the way. Running a 30 that has a cSt of 10 to 11 doesn't concern me.
I suppose I could understand using the PP 5/30 if I was driving a lot on a highway but driving around town a lot, I have my doubt the PP would be ideal and end up a 20. Wouldn't I better off using a higher cSt 30? Conversely, a car calling for a x/20 that dilutes or shears would seem to benefit from running the PP.
I'm going to use PP 5/30 as an example but any other oil in the same grade with a 9 range cSt would be similar, I think.
We know that that shearing and dilution decrease the viscosity and Pennzoil, like the the others, routinely say their oil is resistant to shearing and stays in grade but they don't know what vehicle the oil is going on. If you have a diluter, such as certain Honda's, the oil is going to thin out without question.
If I run a recommended interval of say 5 -10k, the oil will shear or be diluted to a degree and my concern is that a thin 30 will end up as a thick 20 somewhere along the way. Running a 30 that has a cSt of 10 to 11 doesn't concern me.
I suppose I could understand using the PP 5/30 if I was driving a lot on a highway but driving around town a lot, I have my doubt the PP would be ideal and end up a 20. Wouldn't I better off using a higher cSt 30? Conversely, a car calling for a x/20 that dilutes or shears would seem to benefit from running the PP.