There seems to be a ton of bad information in here regarding oil. You guys should head over to Bob Is The Oil Guy (BITOG) forums and read up.
www.BobIsTheOilGuy.com
One of the biggest myths in this thread is oil is bad if it is dark in color, or good if it is still clear. If the oil is dark in color is can still be excellent, doing its job keeping the internals clean, with a medium to high TNB content. The only way to see how an oil is doing is having an oil analysis done by a lab.
---------- Post added at 02:40 AM ---------- Previous post was at 02:26 AM ----------
Wow... 6 pages of heated oil debate.. awesome.. i'm due for an oil change and i've decided to switch to synthetic and get a K&N oil filter. The question is.... Royal Purple or Mobil 1 Full synthetic? I'm sure it's all opinions but I want to know which of you synthetic oil people use, and why you chose that one. Thanks guys and great debate.. to each his own!
Royal Purple doesn't have their oil certified by different agencies and car manufactures like Mobil1 (M1) does and other big oil brand oil manufactures like Pennzoil, etc. This speaks volumes in the oil community world (go check out Bob Is The Oil Guy).
In the United States, synthetic oils are classified as synthetic if they use III base stocks or higher. In Europe, for a synthetic oil to be considered synthetic it has to be a IV base stock.
With that said, I run M1 0w-40 in my 2001 Tahoe. It's the only M1 oil that uses IV base stocks in it's oil (true synthetic). All the other Mobil1 synthetic oils in the United States use III base stocks. M1's 0w-40 also carries the most oil certifications and is backed by more car manufactures than any other oil on the planet. It is also the most tested oil in the world when it comes to meeting these special certifications.
Take it for what it is, but certifications, testing, and manufacture support speaks way more volume to me than seeing a nice marketing campaign like Royal Purple uses.
I know M1 0w-40 is expensive and hard to find, that's why I buy it when it is on sale. I picked up 36 quarts when it was on sale at Kragen a few months back for $4.99 a quart. Over a $1 cheaper per quart than Wal-Mart at the time.
Keep in mind, M1 5w-30 is the factory fill for most, if not all GM vehicles coming off the line. With that being said, you can be assured all of GM's motor testing, hours of R&D, etc. was done with M1 5w-30. Since this is the case, a lot of people, including myself, see no point in running a different oil since the new GM vehicles are rolling off the line with this exact oil.
And a lot of people think oil filters are all built the same. That is not the case at all. The general consensus on BITOG is K&N, PureONE, Mobil1, Napa Gold, WIX, and Fram Extended Guard are the best. The worst oil filters would be any Fram that is not the Extended Guard model (Extended Guard is the only one with metal end caps inside the filter).