Zinc additive

Look for oil with an SL and earlier rating (but not as far-back as SB ! ha ha ha ) , or SM so long as it's got ZDDP in it .

I use Valvoline 4-Stroke motorcycle Oli as it's got ZDDP in it already ; alternately , "Racing" oils are acceptable ( Valvoline , again , but mostly all you'll find in stock are 30w , et seq.) ; and even the fledgling synthetics have specific "break-in" oils (Royal Purple , for instance) ; or , in the case of Mobil1 , their 15w50 has the most ZDDP versus other common brands .

The API ( American Petroleum Institute ) , via pressure from the auto manufactures once 100,000 warrentees hit in 2006 , removed ZDDP from motor oils . The shitty part is that they failed to change the rating (to something like "SP") !!