Use any oil you like in a 10-30 or 10-40. No synthetic oil, straight weight will also work. 15-40 is to thick, you need it to really splash around for a good cam break-in, and diesel oil no longer has enough additive for a proper break in, it has been reduced down like all other oils.
ADD break-in supplement to what ever oil you choose, I like Comp Cams or GM EOS, both easy to get and work good. Comp Cams also makes a break-in oil with enough additive in each bottle. Brad Penn oil is very good also.
Run the engine for 20 minutes or so, KEEP IT COOL, over heating is really bad! Garden hose over radiator really helps. RPM is key to oil splash, no oil is pumped to the lifter / cam contact point, its all splash off the crank. With out rpm (1800 + ) oil will not coat the cam lobes and you risk premature wear or total break down. With heavy springs, a cam can be worn out in as little as a few revolutions of the engine. Have the fuel and timing close, do not slow rpm to adjust. If you must adjust, do it at high rpm or wait till you are done with break-in. REMEMBER, it's the first few minutes that are most important!
I run the break in oil for 400 or 500 miles with just a filter change and quart to top off the oil level. All the good stuff keeps working, and if you cleaned the engine before assembly, the oil will stay clean. If you want to change oil right away, use what ever brand you are happy with plus 1/2 quart additive with each oil change hear on out till you get tired of buying additive. I would say after 10,000 miles the cam will be fully broke in and with your weak valve spring pressure, additive will no longer be needed.
Spring pressure dictates how much and how long to use Zinc additives. Full race engines need it for ever, used everyday engines don't need any, and broke in engines only for a while.
