Engine/Transmission (1998.5 - 2002) 15W-40 vs. 5W-40 synthetic

[Silver_Ram]

I know they say your supposed to use the 15W-40, but why couldn't you use the 5W-40 year round. When the oil is hot they are both 40 weight correct?



Thanks,



Troy

 

[BDMiller]

I do use 5W-40 Mobile 1 Delvac year round with no problems. Seems to crank a little easier in the winter. The oil weight recommendations are based on temperatures you can expect to experience so if it gets real cold where you live go for the 5W-40.

 

[johncameron]

I'm running 0W-40 shell Rotella T-SB year round and it makes a huge difference for starting when it's below 0 in the winter.

 

[Cooker]

If you both options are synthetic, there is no reason not to go with the 5w40 year round.

 

[Silver_Ram]

I've been running 15W-40 synthetic & haven't really noticed any difference, & I thought about trying the 5W-40 synthetic. I figured it help cold starts, but when I tow my 5th wheel trailer, I'm not sure if the 5W-40 will be enough. .



Troy

 

[jwilliams3]

At temp the oil is 40 weight so there is no difference.

 

[DCaswell]

I have been using Esso 0w-40 now for 3 years & very happy with it. Truck starts easily when cold if it could not be plugged in

 

[GKinney]

me too

I've used Mobil Delvac 1 in mine for about 5 yrs now,,, run it year round. Just did valve lash adjustment last weekend at 89k mi. , everything looks like new under the valve cover!! I'm sold.