Synthetic oil in rebuilt engine?

[doctorgonzo]

I've been running the Rotella on Ed and others recommendation. I may decide to go synth after this rebuild. Not sure how my temps are gonna be with the bored out head.

[Agemax]

i have always worked on the idea that if you rebuild an engine, whether standard or beefed up, dont matter how meticulously you build it there will always be some nasty bits and pieces floating around in there.
on initial start up, put some cheap oil in and a new filter. let it run and get hot, maybe even do a few miles on it but no more. then drain it, flush it, and get rid of any unwanted particles floating around in the motor.
then install a new filter and some decent oil and ride it. after a few thousand miles, drain it again, new filter and some more decent oil.
may sound expensive but cheaper than another engine rebuild and to me...piece of mind that the oil is clean and free from impurities that WILL be present from any engine rebuild.

[Planecrazy]

Don't EVER use synthetic in our old GS's ... they don't know what to do with the "newfangled" oil!************ (Just kidding, in case you didn't notice the many astericks!)

I'm planning to use Rotella T Synthetic, since others here have recommended it and I buy it already for my diesel Excursion...

Regards,

[Nessism]

One, synthetic oil IS slipperier than dino-how do you think it decreases friction?

Two, synthetic oil can be either paraffin based stock or polyester based stock.

Three, there is "synthetic" oil-that is, super-refined dino oil, such as Mobil1, Valvoline, etc, that the government allows to be CALLED synthetic (Group IV) and then there are the TRUE synthetics (Group V), such as Red Line, Royal Purple, and Amsoil.
And they have combinations of both, too.

Those engines coming from the factory with synthetic in them have been run on a dyno with conventional oil in them before filling them with synthetic.

The EPA now limits the levels of zinc. Oils like Rotella have higher levels than others, but no more than the EPA allows. If you want more, you have to go to the true racing oils (not the stuff at Auto Zoo, like valvoline racing), but like Royal Purple, etc. Since it is made for actual racing applications it is not limited by the EPA.

What information do you have that says that synthetic oil reduces friction? And where did you come up with this information that engines are “run in” on different oils compared to what they ship the vehicle with? I’ve never heard of this before and frankly find it amazing if it is true.

Regarding base stock for synthetic oil, there is group 3, 4, and 5. Group 3 is the super refined dino oil (Rotella, Pensoil synthetic, Vavoline synthetic, etc), Group 4 is called “Poly-Alpha-Olefin” or PAO (old style Mobile One, Amsoil) and Group 5 is Ester based (Redline).

Regarding synthetic oil being lower friction, I don’t believe this is true other than under extreme temperatures where dino oil brakes down.

For some good information on engine oils read this link or go to Bob Is The Oil Guy forum. http://www.calsci.com/motorcycleinfo/Oils1.html