Castrol GTX or Castrol Syntec 20W50?

[Ely]

  I think Bob has a valid point.  But Big Cahuna put it best when he said just cause you pay more for it don't make it better.  Hey isn't that the reason we all bought Harleys ? After that statement I'll run and hide.  We are pretty much  with the oil treads.  It's your ride use what you want if it isn't the right oil you will know it soon enough.

[EagleFTE]

Going back to the original post, I have used Castrol GTX numerous times over the past couple of decades in air cooled engines.  But knowledge from those experiences are now obsolete.  When they lowered ZDDP in oil bottled in 2008 to save the precious cat converters GTX has dropped of my list of oil options.  Even Castrols customer service reps are NOT recommending GTX 20W50 for many traditional applications and that says a lot!  I would say if you want $3 - $5 oil that the Valvoline ZR-1 and Vtwin dinos or the M1 15W50 (best in that price range IMHO) in the 5 Qt jug at Walmart are amoung the best choices.  If you want something top shelf with a ton of ZDDP and detergents on top of a killer Group V base oil I have been getting Red Line by the case for $8.20 per Qt.  But it's your bike and you have to decide what to spend on oil.  I have no interest in putting a Group II dino with a weak additive package in my bikes unless it is for winter storage or a very short OCI (which kills the cost savings anyway).

And this subject really isn't beating a dead horse since the SM/CJ-4 API rating requirements have had a significant impact on what is in the bottle.  Especially with respect to flat tappet engines, muscle cars, air cooled bikes and cars, and anything else that take comfort in high ZDDP levels.

[FLTRI]

Eagle,
Very well put!!