Good, bad, either?

 

Either.

 

Like anything else, it depends.

If you're putting on a lot of miles and changing it 2 or 3 times a year you might want to save a few bucks with conventional.

If not, it is probably advisable to go with a syn for year-round protection, including better cold flow if you live where it gets cold. Just remember cold starts happen anywhere, anytime all the time, and that's where most wear occurs.

In any case, synthetics are going to give better performance under all conditions. I view the first statement I made as a false economy in the long run, but it's your money.

 

In virtually all cases synthetic oils are superior for a lot if reasons. Ever note that the manufacturers have all switched to synthetics along with their lengthier warranty periods?

But, note that, like all things these days, the term "synthetic" can stand for differing grades of oil, from re-refined petroleum base stocks with additives to full-on ester-based synthetic stock. One must do some homework to know the difference and why it matters.

I prefer Amsoil as it is a true synthetic in its XL line.

In a diesel, cost is an issue. Unless one runs a good bypass filtration system the double-cost synthetic is no bargain. But if one can extend drain intervals then it pays for itself at about the third regular change. On my gasser vehicles I run about 20k per change and I typically run my vehicles into the 300k mile range before selling them.

Also, lots of stupid mythology out there about synthetic oils and I expect the next 10 posts to fit in that realm.

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I'm a Schaeffer 9000 guy all the way...because of their choice of additives... and this is probably exactly what MR. Fredrick was talking about when he said, "lots of stupid mythology out there about synthetic oils and I expect the next 10 posts to fit in that realm". but I can't resist... and I promise to try and keep to the facts and not throw any myths out there.

My main reason for my decision to use Schaeffers 9000 is the amount of "Micron Moly" as they call it, used in their product. It's Based off of molybdenum and is a slightly lower temperature rated metal bonding/lubricating agent than what is use on Rolls Royce aircraft powerplant to protect the single crystal grown rotary blades from friction induced failure. Amsoil, also an amazing lubricant/protectant, uses a very similar compound in it's full synthetic product but in a lower quantity. This is the reason I personally choose Schaeffer 9000 over Amsoil XL.

but to answer your question...
True Synthetic oil is good.

With regular and timely oil and filter changes you would be fine using just about any properly rated diesel oil, however true synthetic oils are by far the best choice when it comes to full engine protection and they can be ran for longer intervals while maintaining proper protection. (FYI...royal purple is not a true synthetic oil)

 

I approve of Schaeffer's. Good stuff.

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Does anybody know of any studies or independent tests showing that Amsoil XL, Shaeffer's with the super-duper moly stuff or any other oil for that matter performs any better than another brand's comparable grade product?

Let the realm establishment begin.

 

http://www.turbodieselregister.com/TDR57_Oil.pdf

 

So it looks to me like the answer to my question is "no."

There is no reason to expect much of anything different from any brand's oil in the same grade/type category.

Except price.

And you might even occasionally be surprised to see the good performance of some relatively "cheap" oils.

Would that be about right?

 

All I know is to learn as much as you can and research a lot. The prices on that list differ from where Im at, The Valvoline here is 17.99 a gallon. Im no oil expert I just know lots of tbn and zinc are what I look for.