[cnavarro]

Originally Posted by JFairman

While at Walmart buying all the mobil one v-twin 20-50 they had in stock at somewhere around $8.40 a quart, I saw Castrol 20w-50 non synthetic 4 cycle motorcycle oil in quarts next to it.
(they had a Castrol 2 cycle motorcycle oil version too but it can't be good for us)
I havn't heard any mention of this oil so I wonder how it compares in the zddp levels department. It was around $2.75 a quart.
It may be very good stuff...

Charles, I've been wondering if you've checked it out yet?

I'm sure the Castrol 20W-50 motorcycle oil is better than GTX 20w50, but by how much. It's come down to the fact that yes, some oils have acceptable levels of Zn and P, but there are clear performance differences between them. Long term use and continual UOA among multiple users will be needed to give definative proof of a product's viability, as has been done with Swepco and Brad Penn.