A couple of posters at different times on this board have speculated that re-refined oils may be better than 'virgin' oils b/c the process starts out with oils that have already been processed, so by re-processing them, you get out even more unstable junk and end up with a stronger oil.
A lot of people tended to disagree, saying there is no guarantee that the oils are put through as stringent a processing the second time around, so you may or may not end with as good of a product.
I think I may have found a bit of proof that these oils may in fact be more shear-resistant than group II or even III oils. Take a look at this UOA:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000882#000000
After 5000 miles, the viscosity of this oil was still 10.4, comfortably in the range of 30-weight oil. Now before saying this engine is easy on oil, take a look at these other two UOA's:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=003137#000000
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000693#000000
In the first one, this engine sheared a syn blend to a 20-weight (last column). In the second one, the same engine sheared a group III syn. to a 20-weight as well. I know this is just one UOA that doesn't show shearing, but it is pretty impressive comapared to the other two.
The whole point of this post is that there are a few people on this board who don't like the way dino oils shear out of grade, and the general thought is that the only way to avoid this is to go to much more expensive synthetic oils. Maybe using re-refined oil is a way to achieve this end cheaper?
Another complaint about re-refined oils is that they tend to be sold at the lower end of the scale, and so the add packs are not as strong as they could be. Maybe a re-refined oil with something like VSOT, #132, or SX-UP is the way to a cheaper, shear-resistant, high-performance oil....?
I know subjectively, I used Tech 2000 5W-30 in my Cavalier for 6500 km's, and the car 'felt' much smoother for the whole oci.
A lot of people tended to disagree, saying there is no guarantee that the oils are put through as stringent a processing the second time around, so you may or may not end with as good of a product.
I think I may have found a bit of proof that these oils may in fact be more shear-resistant than group II or even III oils. Take a look at this UOA:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000882#000000
After 5000 miles, the viscosity of this oil was still 10.4, comfortably in the range of 30-weight oil. Now before saying this engine is easy on oil, take a look at these other two UOA's:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=003137#000000
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=000693#000000
In the first one, this engine sheared a syn blend to a 20-weight (last column). In the second one, the same engine sheared a group III syn. to a 20-weight as well. I know this is just one UOA that doesn't show shearing, but it is pretty impressive comapared to the other two.
The whole point of this post is that there are a few people on this board who don't like the way dino oils shear out of grade, and the general thought is that the only way to avoid this is to go to much more expensive synthetic oils. Maybe using re-refined oil is a way to achieve this end cheaper?
Another complaint about re-refined oils is that they tend to be sold at the lower end of the scale, and so the add packs are not as strong as they could be. Maybe a re-refined oil with something like VSOT, #132, or SX-UP is the way to a cheaper, shear-resistant, high-performance oil....?
I know subjectively, I used Tech 2000 5W-30 in my Cavalier for 6500 km's, and the car 'felt' much smoother for the whole oci.