no one at valvoline will give me a straight answer on this. i buy valvoline 4 stroke full synthetic in 10w-40 for my stryker and 20w-50 for my HD sportster. it runs about $9 a quart. on amazon you can buy both as a 6 pack in auto version for $6. the auto version does not have that conservation label. are these basically the same oil, just marketed for more $$$?. i have been told that as long as that conservation thing is not on bottle you can use in M/C's also. i know i did it in my 1982 yam xj550 for 25+ years.