break in oil and changes

roylerumble said

correct me if Im wrong, but isn't a multi viscosity oil like 5w 20 or 10w 30 suitable for multi temperatures and the 5w or 10w refers to the cold weather viscosity, lower the W number the thinner at cold temps? So SAE 30 would be the same at any temp? And break in oil has zinc and phosphorus addivitves for break in. Or is there a difference between conventional oil and break in oils....?

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Look at it this way.
The 5w30 oil is going to act like a 5 weight oil during start up of a COLD engine no matter if it's 40 below or 100 above zero.
Also, the ''w'' stands for winter not weight.
So, 5w30 is actually 5 winter 30 not 5 weight 30 as a lot of people believe.
When the engine is stone cold, the engine is in ''winter'' mode, so the viscosity of 5 is faster and easier to get to major lubricating points as early as possible. The oil thickens to 30 as the engine warms up.
After the initial break in with the break in oil, you still need to have a high zinc etc. package in the future oil for the rest of the engine's life whether it is already in the oil or it is added to conventional oils during the oil change.
Unless you have a roller cam, this is the reality of using a flat tappet cam these days in an older engine............