Oil viscosity 10w30 vs 5w20?

Been using 10w30 oil in 96 ford winstar and found out it should be 5w20 which am guessing is thinner is 10w30 too big a diff from 5w20 or is it ok its been 2yrs on 10w30

It offers more protection for the engine, particularly in high-mileage engines and in warm conditions, but might wear out your oil pump more quickly. That pump wear is probably the biggest concern you should have, which is to say it isn't a big deal. If you drop to a lighter weight you might see a little better fuel economy, though.

Some auto enthusiasts swear by using a heavier oil weight during the summer and a lighter weight in the winter, and if you live in a climate where extreme temperatures are common this may be a good idea. But for me, I stick with what's in the owner's manual.

I would keep on using the 10w-30 in an older engine like that.

You will be fine with 10w-30.

5w-20 is considerably thinner and you may hear some engine noise now if you switch since I assume it has considerable mileage on it.