To be rated a 2T oil must have low smoke additive package. That means polybutene additive, and a solvent to thin the additive, so it can be used in injection systems. Solvent is likely to be around 20% by volume of the oil.

I got that information from the tech department of Silkolene Fuchs, and it was confirmed by the Castrol tech department, Dusseldorf.

It not something that really matters for a trail bike in a low state of tune, but not a great idea to use what is essentially road bike oil, if you have any sort of serious competition bike.

That surprised me when I was told, but it was confirmed by a lab report, which showed that a very well known "fully synthetic" 2T oil was anything but.

For low heat engines, the pseudo "full synthetics" are fine, as the low smoke package, significantly reduces exhaust clogging. For pre-mix bikes, its a good idea to bear in mind its not a good idea to run low smoke oils at the same ratio, as race only products. As long as thats taken into account, all will be fine.

Yamfan,

It sounds like the definition of synthetic you're subscribing to has some sort of "fully synthetic" or "purity" requirement?  No additives allowed?   

It is widely accepted in the engineering and by standards organizations (i.e.API, SAE) that "fully synthetic" is a marketing term and NOT a definition. (So my guess is what you were told originated in the marketing departments.) 

Mineral or "conventional" oils are refined from crude oils. 

Synthetic means the base oil was derived "synthetically"... in other words man-made or synthesized...  often from breaking down and rebuilding the petroleum molecules of crude oil into uniform artificially made chemical compounds.  Synthetic oils can also be synthesized from other base stocks (commonly PAO's or Esters).  There are many classes of synthetic oils (depending on starting base stock) and most synthetic motor oils have additive packages, detergents, etc.  Additives do not somehow make an oil "non-synthetic".   (Unless the "additive" is conventionally refined mineral oil...  then you have a "semi-synthetic" oil by definition.)

In any case, I'm pretty sure polybutene is a synthesized (man-made) compound.  And if adding a "solvent" makes the oil non-synthetic, then it's literally impossible to actually have "fully synthetic" lubrication in most two strokes.  Gasoline is a great solvent (albeit highly flammable and dangerous) so once the oil is mixed in gasoline the oil is no longer "fully synthetic".  I know what I just said about gasoline is pushing the definition to the edge...  just pointing out that words are symbols we apply meaning to.  And those meanings change in different cultures and even with different individuals. 

It's when the definitions of those symbols agree that communication is best.  I don't agree with your definition of  "fully synthetic".  And I'm not asking you to agree with mine.  I do appreciate the opportunity to hear your perspective and to share my perspective.

P.S.  This certainly was a lot easier than trying to explain to my friend Cheryl from the UK that suggesting she get a "fanny pack" before the hike we planned to take was not meant to be crude or offensive.  The term "fanny" has a very different meaning in the UK. 

(For those who read this far, "fanny pack" = "bum bag" in the UK, Google can give you the UK definition of "fanny")

"P.S.  This certainly was a lot easier than trying to explain to my friend Cheryl from the UK that suggesting she get a "fanny pack" before the hike we planned to take was not meant to be crude or offensive.  The term "fanny" has a very different meaning in the UK. 

(For those who read this far, "fanny pack" = "bum bag" in the UK, Google can give you the UK definition of "fanny")"



No idea why you American chaps had to change the meaning/spelling of some words!!! 

The difficulty with branding road/play bike low smoke 2T oils as "fully synthetic" is that at least 20% of these oils (by volume), will be low smoke additive/solvent, and it's not appropriate to mix them at the same ratios as actual fully synthetic race oils (if you want to run 70,80,100:1)

For injection bikes, or pre-mix (as long as mix ratio isn't too lean), using a low smoke "fully synthetic" makes zero difference, and is probably a better choice than a proper race oil, as the exhaust system will stay cleaner for much longer.

The reason serious 2T racers are not likely to use low smoke oils, is that the additives reduce lubrication performance, and don't provide as good corrosion protection, for bikes that are used infrequently. That the full race oils clog the exhaust much faster, doesn't matter much to a racer.

I suppose the main reason the "fully synthetic" term is applied to oils that aren't, is probably due to issues with shipping full synthetic race oils? Take for instance Bel Ray MC1 easily available in the US, but nowhere to be found in UK. Is Castrol XR77 or A747 available in the US, I wonder?

"it's not appropriate to mix them at the same ratios as actual fully synthetic race oils (if you want to run 70,80,100:1)"

Most regular liquid laundry detergents contain a lot of water.  Some brands sell "concentrated formula" version without the extra water so you use less per load.  The actual detergent is the same, one just has some "solvent" (water) added.  If you can't follow the manufacturers instructions and try to use the measurement cup for the "concentrated formula" with the "regular formula" soap your clothes won't get clean. 

If an oil manufacturer adds some solvent to their oil to make it suitable for injection pumps, yes, that solvent will reduce the oil and that oil cannot be safely "premixed" as lean as the same oil that has not had solvent added.  Manufacturer recommendations for premixing will reflect this.  As with laundry detergent, it could be the same oil but you need to use more when premixing because it already has some solvent added.  

Bottom line: Follow the manufacturers recommendations. 

P.S.  I'm not a fan of extremely lean oil mixes, synthetic or not.  Especially with these old Enduros.  In my racing experience, running an oil that will burn (most high-zoot synthetics don't), and a lot of it, results in more HP and more won races.  I'm talking high speed racing, in something like a trials competition, there might be an advantage to running less oil?  But that's a skilled competition, not really the same demand on the engine or oil as running full throttle in deep sand for miles on end in 100F + temperatures. 

The reason for authentic race type synthetic oils, having a high flash point, is so that lubrication performance can be maintained, when used in applications such as road racing.

It's not that great an idea to use these oils for any application, which doesn't involve high temperatures and RPM, for extended periods of time

The low-smoke "full synthetics" though are fine, as while they won't lubricate a high temperature race motor, as well as a race oil, will work fine in almost everything else.