Jeep 4.0 Mobil Delvac 15w-40

[dgee]

What type of OCI should I run with Delvac and a 1996 Jeep GC 4.0
I picked up 5 gallons and want to use it during the warmer months.
I searched the forums but couldn't find a definitive answer for the 4.0 and 15w-40.
and also would i notice a big difference in gas mileage?

Car is driven 20 miles city round trip daily and 100 miles highway round trip every sunday. Moderate on the pedal with RPM's never exceeding 3K. also around 140K on the engine.

thanks guys

 

[Chris142]

The HDEO 15w40 will go 6k easily in your conditions.

 

[440Magnum]

Originally Posted By: dgee

and also would i notice a big difference in gas mileage?


What's it going to do, go from "lousy" to "royally lousy?"



Seriously, I doubt you'll see a big difference if any. The Cherokee's mileage is limited by the shape of the vehicle and the wastes in the AW4 tranny. What do you get, about 16? My 5-speed that my daughter drives will break 21 on the highway, but not my automatic.

 

[dgee]

Originally Posted By: 440Magnum
Originally Posted By: dgee

and also would i notice a big difference in gas mileage?


What's it going to do, go from "lousy" to "royally lousy?"



Seriously, I doubt you'll see a big difference if any. The Cherokee's mileage is limited by the shape of the vehicle and the wastes in the AW4 tranny. What do you get, about 16? My 5-speed that my daughter drives will break 21 on the highway, but not my automatic.


Well it's a 42RE and i get about 18 MPG with Rotella 5w-40.

 

[addyguy]

7-8k easy.

I'd say 10k, but too many here would scoff at that!

 

[gomes512]

I took Rotella 15w-40 on the 4.0 out to 7.5K for the past 4 summers. TBN still always rang up above 1.

 

[dgee]

Originally Posted By: addyguy
7-8k easy.

I'd say 10k, but too many here would scoff at that!


sounds good. also what would be the minimum temperature to start using this oil. lately the temps have been from middle thirties to low fifties.
i dont want to risk any unnecessary start up wear with a 15wXX oil.

 

[rslifkin]

Personally, I'd say that once it's at least in the 40s consistently, and won't get below freezing at night, go ahead and switch. Just go easy on it for the first couple minutes after startup if it's below 60 - 70*.

 

[440Magnum]

Originally Posted By: dgee
Originally Posted By: 440Magnum
Originally Posted By: dgee

and also would i notice a big difference in gas mileage?


What's it going to do, go from "lousy" to "royally lousy?"



Seriously, I doubt you'll see a big difference if any. The Cherokee's mileage is limited by the shape of the vehicle and the wastes in the AW4 tranny. What do you get, about 16? My 5-speed that my daughter drives will break 21 on the highway, but not my automatic.


Well it's a 42RE and i get about 18 MPG with Rotella 5w-40.


Woops, I saw the GC and somehow my brain read "Cherokee." You're lucky. The 42RE is as much or more of a power-soak as the AW4, but at least it shifts better... and you have rounded corners for better aerodynamics ;-)

 

[dgee]

Originally Posted By: 440Magnum

Woops, I saw the GC and somehow my brain read "Cherokee." You're lucky. The 42RE is as much or more of a power-soak as the AW4, but at least it shifts better... and you have rounded corners for better aerodynamics ;-)


i wish i drove around in a jelly bean

but i'm getting 18mpg with 31's and a basket on top. can't complain

Originally Posted By: rslifkin
Personally, I'd say that once it's at least in the 40s consistently, and won't get below freezing at night, go ahead and switch. Just go easy on it for the first couple minutes after startup if it's below 60 - 70*.



sounds good thanks!

btw my oh my how Stamford has changed these past few years. Every time I pass by on 95 i see something new being built!

 

[pavelow]

Originally Posted By: dgee
What type of OCI should I run with Delvac and a 1996 Jeep GC 4.0
I picked up 5 gallons and want to use it during the warmer months.
I searched the forums but couldn't find a definitive answer for the 4.0 and 15w-40.
and also would i notice a big difference in gas mileage?

Car is driven 20 miles city round trip daily and 100 miles highway round trip every sunday. Moderate on the pedal with RPM's never exceeding 3K. also around 140K on the engine.

thanks guys
For your climate, I'd run 5W40 Rotella T6. It'll make life easier on your starter in the winter and your oil psi will rise faster upon startup with the thinner 5W. I ran Rotella T6 in my Jeep 4.0 for many years and liked the oil. A weepy rear main seal made me make the move to M1 high mileage 10W40.