What you have in there now is incorrect get rid of it. When you do get the normal stuff back in post your readings and let others tune in with comparisons and comments. I would not waste money on fluid additives.
From wiki:
Advantages
The technical advantages of synthetic motor oils include:[citation needed]
* Measurably better low and high temperature viscosity performance
* Better chemical & shear stability
* Decreased evaporative loss
* Resistance to oxidation, thermal breakdown and oil sludge problems
* Extended drain intervals with the environmental benefit of less oil waste.
* Improved fuel economy in certain engine configurations.
* Better lubrication on cold starts
* Longer engine life
[edit] Disadvantages
The disadvantages of synthetic motor oils include
* The lower friction may make them unsuitable for break-in (i.e. the initial run-in period of the vehicle) where friction is desirable to cause wear. Improved engine part machining has made break-in less critical than it once was, though. Many modern cars now come with synthetic oil as a factory fill.
* Potential decomposition problems in certain chemical environments (industrial use dominantly)
* Potential stress cracking of plastic components like POM (polyoxymethylene) in the presence of PAOs (polyalphaolefins).
* Synthetics do not hold lead in suspension as well as mineral oil, thus caution is advised when the engine is run on leaded fuel.[citation needed] As an example, leaded fuel is still commonly used in aviation (avgas).[17]
* In July 1996, Consumer Reports published the results of a two year motor oil test involving a fleet of 75 New York taxi cabs and found no noticeable advantage of synthetic oil over regular mineral oil.[18] In their article, they noted that "Big-city cabs don't see many cold start-ups or long periods of high speed driving in extreme heat. But our test results relate to the most common type of severe service — stop-and-go city driving." According to their study, synthetic oil is "worth considering for extreme driving conditions: high ambient temperatures and high engine load, or very cold temperatures." [19]
* Synthetic oils are not recommended in automotive rotary engines.[20]
