There is a difference, but you can't measure it.        bob

i was in walmart and noticed they have castrol gtx in 5w-20 grade so decide
with this oil change in my old 1988 honda civic i'm using the newer grade
hopefully it won't cause any damage. i don't think it will and i think it'
going to be an improvement. less strain on the crank shaft and pistons
anyone who has any knowledge about the newer oil please let me know. thanks

-jef
the newer grade of oil is just for that for newer vehicles."  you have used it? shoulden"t harm  your engine  in  fact you might even gain a slight increase in gas mileage from the thinner viscosity".  however  i would not take a chance on my engine.  on your next oil change switch back to what  the manufacture  has called for ;

--
johnin

The only thing it do for you is increase oil consumption. The viscosity was
changed for new cars so they could post a slightly increase in corporate gas
mileage. Stick with the viscosities your car recommends unless you need a
heavier weight because of oil consumption....