I have read on BITOG a couple of times that a 5w30 will shear down to a 20 weight. If that is the case what does a 20 weight shear down to and is that to thin.
Polymers can shear and burn forming deposits that can cause ring sticking and other problems. Polymers are used to blend and mutil weight oil. Since 5w30 has to use more Polymers to achieve its Visocity spread it is more like to shear.
I gather that dino engine oils will shear to be a bit thinner after 2-5,000 miles. After that, they can start to change chemically and get thicker as the miles rack up.
Full synthetic oils shear less, and thicken less, than dinos.
Originally Posted By: posty
I have read on BITOG a couple of times that a 5w30 will shear down to a 20 weight. If that is the case what does a 20 weight shear down to and is that to thin.
I have noticed 1 or 2 oil reports for used 5w-20 that sheared out of grade. If you're worried about your 5w-20 you could switch to Castrol or Redline because they're a little thicker than the others.
