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#5: 05-21-2011, 12:51 PM
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There is a lot of misinformation in this thread, and it's not even that long yet.

First of all, to the OP, the reason people say not to use synthetic after using conventional oil is that, theoretically speaking, the additive pack in the synthetic will dissolve the deposits of dino oil around seals. With the deposits gone, there is more room around the seals for the new oil to leak out. I'm not sure I buy this argument, though. Plenty of people switch without having any problems, and if you have oil leaks, you should replace the seals, not pray that the deposits keeping the leaks manageable stay there.

Originally Posted by broknindarkagain View Post
The other kind of synthetic oil is REAL synthetic oil. There isn't much around, and what is around is VERY expensive. Amsoil is the only company that makes real synthetic that I'm aware of.
Shell Rotella T6, German Castrol Syntec, and I beleive Pennzoil Platinum are also true synthetics (i.e. PAO base stocks rather than refined dino base).

Originally Posted by broknindarkagain View Post
This kind of synthetic isn't suppose to be mixed with conventional, or even conventional based synthetics. This type of oil is built in a lab from scratch. Its 100% man made, where as your normal synthetics are just modified conventional oils.
Where did you hear that? They are all oil. The advantage of synthetic is that it breaks down more slowly and (usually) has a better additive pack. Normally, you don't have to change true synthetics as often as dino oil. Some are reporting 7500-10000 mi. between changes on EJ255s (notoriously hard on oil) with Rotella T6, and the UOAs say the oils even have a bit more life in them. But, if you were to mix Rotella T6 with Quaker State (widely considered to be crappy oil), as long as you keep an appropriately short OCI, there is no way you can damage your engine.

Originally Posted by Baddog View Post
I just feel as if I am getting better protection from using a Synthetic. A good brand at that. My engine feels smoother with RP. I was running Shell and Mobil-1 before.
Too bad Royal Purple does not have any oil industry certifications. If you want to talk about selling "snake oil," Royal Purple does it. Maybe they are good, but they have no proof.