Originally Posted by paoester
Why not use the 8600 10w30 version of valvoline premium blue? It has HTHS=3.5 which is above Ford's recommendation of at least HTHS 2.9. Your 15w40 thick soup has HTHS 4.3, another category.
3.5 is plenty extra for fuel dilution and FL heat.
Because I got the 15w40 on sale. LoL that's the bitog way, right?
BTW it has delo in it now because I had 2 gallons on the shelf.
I don't think this engine cares what oil is in it to some extent.
Originally Posted by jetman
Looks to me to be thickening a little, possibly due to oxidation. Virgin viscosity is 15.1 @ 100 C. Otherwise looks good.
Here the product data sheet:
VPB 15w40 info
What scenarios cause thickening? I will look up oxidation issues