10w40 drawbacks

[tahiti429]

Your valve noise could be caused by worn rocker arms and push rods. Delta cams makes a kit to replace rocker arms and push rods. I have done this on my high mileage 95 4.0 ranger with great results. Search this forum, I'm sure someone has posted about it.

 

[bjurke]

the problem with 10w40 is the start up viscosity is too high. oil filter will be in bypass until oil warms up. the hot viscosity is too high. upper valve train lubrication will be poor until oil warms up. use what ford recommended. this info is off of (bob the oil guy) web site.