Will 5w-40 Synthetic handle the heat of summer??

[Dzlnut]

I know that running synthetic in a 6.0 is the holy grail but you dont hear much about the subject with 6.4 guys. Is synthetic the way to go on the 6.4 or is it best to just stick with 15-40. I ran T-6 Rotella in my 6.0 and liked it but I was always a bit nervous to run it in the summer towing. I realize the the 6.0 and 6.4 are a completely different animal, I want to run what is best for longevity.

 

[Dave]

A 40wt oil is a 40wt oil the 5w addresses cold flow properties. You will be fine running it year round

 

[SDS97_7.3]

I run the Valvoline Premium Extreme blue 5w40 in my 6.4 year round

 

[swinky]

I run the Valvoline Premium Extreme blue 5w40 in my 6.4 year round

Looooooove that oil.

It's noticeably smoother than t6 in my truck.

 

[Black_Pstroke]

I run the Valvoline Premium Extreme blue 5w40 in my 6.4 year round

:whs:

 

[Dzlnut]

Thanks for the feed back guys.

 

[fine69]

I run the Valvoline Premium Extreme blue 5w40 in my 6.4 year round

Same here.

 

[Dzlnut]

I ended up using T6 5w 40 rotella synthetic

 

[Crazysob]

I usually switch to 15w40 during summer, but its really not a big deal. As they said its just the cold flow properties.