I have '81 and an '82 Honda C70's. I don't know alot about motorcycles, and can't find very specific information online about the oil in these bikes. The repair manual says to use Honda 4 stroke oil SAE 10w40 or equivalent. I realize these bikes are pretty tough and will probably run on just about anything, but being a typical BITOG member, I want to understand what will optimize the bikes' maintenance. My twin boys turn 16 in a couple weeks and will likely be running the stuffings out of these Hondas. Sorry if these questions are a little basic: 1. The bikes have a shifter and gears, but there is not a clutch and they shift like the old Honda 3-wheelers. Does this have a "shared sump" or "wet clutch"? Something different? 2. I used to just run Honda 4-stroke or synthetic PCMO in them, but switched to Mobil 1 Racing 4T motorcycle oil recently. Does motorcycle-specific oil add anything to this type of engine/transmission setup? 3. With a .8 qt sump, money is no object on oil for these two bikes. If you could choose any oil for these, what would you go with? (synthetic motorcycle oil, hdeo, etc) What grade? (10w40, 15w40, 5w40, 20w50) Brand? (Mobil 1, Valvoline, Amsoil, Rotella, Delo)? I would appreciate hearing the thoughts of the BITOG members on what oil I should run in these 40 year old classic Hondas.