Originally Posted By: Steve S
Where are you getting the ideas. What is the switch 0 or 5w supposed to do?
I am getting my ideas from the Oil 101 to 108 articles linked on the front page, specifically Oil 102. 0w and 5w have lower viscosity at 40 C. I have checked this on the specification pages on the Redline, Castrol, and Pennzoil websites.
Quote:
I have heard several people say that Porsche specifically prohibits a 0W-XX engine oil, that it is too thin. Now here is the partial truth I spoke of earlier.
...
Quote:
The downside of a mineral based multi-grade oil is that this VII additive wears out over time and you end up with the original straight 10 grade oil. It will go back to being too thin when hot. It will have a thickness of 6 instead of 10. This may be why Porsche (according to some people) does not want a 0w30 but rather a 10w30. If the VII wears out the 0w30 will ultimately be thinner, a straight 0 grade oil. When the VII is used up in the 10w30 oil it too is thinner. It goes back to a straight 10 grade oil. They are both still too thick at startup, both of them. The straight 0 grade oil, a 5 grade oil and a 10 grade oil are all too thick at startup.
This is just theory however. With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. This is partly from dilution with blow by gasoline and partly from VI improvers being used up. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.
Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. You could almost use the same oil forever. The problem is that there are other additives and they do get used up.
