Oil threads bring out the best in everyone, eh?
On a serious note, I was having some discussion with a friend back in March of this year about MC oil and did a little research on the subject and this is what I came up with:
There is a FAQ note on the Mobil 1 site where someone expresses concern about thrust bearing failures in a high performance engine using modern oils. As it turns out, the EPA specified that engine oils needed to be reformulated to reduce phosphorus to no more than 800ppm since phosphorus adversely affects catalytic converters. Looking at the Mobil 1 oil charts, their Mobil
1 Racing 4T oil is what they specify for all 10w40 spec motorcycles, the zinc/phosphorus level is 1300/1200. That stuff is $10/qt.
Shell Rotella T has a zinc/phosphorus level of 1200/1100. I was at a local hardware store that had diesel oil. Rotella T 15w40 runs about $13/gallon. The one warning I've read about diesel oil is that it has high detergent levels.
Some people prefer racing oils which are not made for on-road cars since that oil does not have all the detergents. Valvoline VR1 can be bought from Amazon for $68/case ($5.60/qt). That oil has 1300ppm of phosphorus and 1400ppm zinc. The only issue there is that the oil doesn't have detergent additives, so oil change intervals should be more frequent.
Amsoil has several oils that have high ZDDP percentages, but they are also in the $10-$12/qt price range.
In addition to people with old motorcycles, the people who have old cars with flat tappets and cam lobes are really concerned about anti-wear additives. There is a tech bulletin on the Amsoil site that addresses that issue specifically, just go to
https://www.amsoil.com/search.aspx and search on 'flat tappet'
For an old bike that isn't an investment, you're probably just as well off running a decent 15w40 diesel oil and you can get Rotella at Walmart, Autozone and the like.
