There are many types of break-in oil out now. Comp Cams sells one, GM EOS, just to name a few. Any local auto parts store will have one on the shelve. Diesel oils do not have the zinc they once did since the new engines now have converters on them just like the cars do. Brad Penn oil is one of the most recommended on the market now. It has the highest levels of additives and many of the cam makers recommend it for break-in.
Any grade of oil will work, the heavy oils such as 15-40 might be a bit much for a new engine, I would step it down to a 10-30 or 10-40 with a quart of additive or a full load of Brad Penn 10-30.
A stock engine is way different then a race or street strip engine as far as valve spring pressure is concerned so less pressure is on the cam lobes. You didn't mention if this is a new camshaft or not so we will assume it is. Pre lube the engine with a drill motor no matter what oil you use, and rotate the crank four complete turns while running the drill motor. This will insure all the lifters are full and the rockers have started to receive oil.
Once broke in, check the oil for metal bits if the engine doesn't have a oil filter, if the oil is still clean, keep running it. A slight amount of material in the oil is acceptable due to cylinder wall and ring wear. What you don't want to see is brass or aluminum floating. After the first 500 miles or so change out the filter only if it has one and add back more oil. You can just change all the oil if you have the money, but be sure to add back the zinc, Comp Cams is $15 per bottle, thats why we run the same oil for a long time, its a lot of money to just dump. If the filter is doing its job, the oil will remain clean for a long time.
Joe
