Hey Guys,

I have a 1999 Ford 7.3L and with winter on the way and the days and nights getting colder I've found my baby getting harder to start.

I don't think I'm having any engine issues its just the cold weather. So as to that I was just curious to what everyone thinks about running 5W-40 vs 15W-40 for cold weather use?

The coldest it's ever gotten here is -23F and that was setting a record, most I can except on a daily basis is 3 degrees F. That being said the 15W-40 at 3 degrees is thick like molasses so would it be better to run 5W-40 for the winter time?

I do plug my truck in every night but while I'm at school she sits out there in the cold all day long with no love.

 

5W-40 full synthetic helps a ton

 

I run 5w-40 year round. Anyone driving in cold weather should be using it at the very least, in the winter. 15w-40 is only for people in the far south where it almost never goes below freezing.

 

Thanks for the reply guys.
I went with some left over 15W-40 Full synthetic from AMSOIL got it free and it seems to be working great and is way less thick at the same temperature vs regular 15W-40.

AMSOIL makes a 5W-40 Full synthetic as well so I'll be checking that out in the near future.

 

So is it a bad Idea to be switching back and forth between the two on a yearly basis? Will this not cause any issues in the future?