Haven't seen that in a while. Does it have to be Castrol "R"?? I've got some buddies that run dirt bikes using Castor oil. Maxima 927 is what they use. Link below.
I use to run Castrol R in my Royal Enfield back in the 60s. Was looking to get an old RE and restore it using Castrol R in it. Love the smell plus it keeps the Lower Bushing in the rod from coming apart. I will look into the Series Caster and see if I can use that.
I have ordered it from them when buying other stuff, but I actualy get it cheaper at the local Honda dealership...I can get it for $12.00 a quart rather than $8.99 a pint.I love the stuff, its all I ever run in my dirt bikes
Yes, with a name like my link above, I figured you ran that castor oil"Maxima927". I haven't seen the Castrol "R" in years. To be honest, not sure if they still make it. OP, maybe check with Castrol to see if it is still manufactured?