[against all odds]

Do you think it would be ok to use 5w-30 in a stock small block?

The reason i'm asking is because i can't find 10W-30(flat lifters) in the store and would rather not do mail-order, although i will if nessesary.

 

[LATECH]

5W 30 will be fine. Lots of myths about motor oil. Like 5 is the cold weight viscosity....wrong.
The first number is a reference to the cold pourability/flowability of the oil.It references the deviation of the viscosity (30) when the oil is cold.
The lower the number the closer it stays to its sae 30 rating when colder.
This means that the oil pressure build quicker(slightly) when cold, by using the 5w 30 than the 10w 30 .
The best way to ensure consistent viscosity and protect against engine wear is to run a synthetic.