Best oil for 96 Jeep 4.0L

[ToyotaNSaturn]

Friend is changing his own oil tonight and asked what's best for his engine. It runs great and has 136K. I told him Delo 400 15w-40, but it's his daily driver and it's still winter 'round here, so that might be a bit thick until spring comes.

Dino or synth....

Suggestions please...

 

[Jelly]

Castrol HM 10w-30

[ February 07, 2005, 04:44 PM: Message edited by: Jelly ]

 

[Tree Hugger]

I use Delvac 1300 15W-40 in my '98 Jeep Sahara with the 4.0L. Year round, no problem, and I'm about 80 miles striaght north of you...

 

[NewGuy]

FWIW..I have this same engine in a 92 Comanche with almost exactly the same mileage. I use Havoline 10W30 with great success. It runs well and uses no oil between 3K OCIs, plus it is $1.16 at Wal-Mart.

I think that Jelly's Castrol 10W30 HM suggestions is a good one as well. After reading the correspondence on BITOG over the last week, I might try one of the HM oils myself. Does the 4.0L burn any oil? Any leaks? Any issues with the PCV valve and deposits? These are common issues with these engines, but with some TLC this engine will last 200K easy. His transmission will probably crap out before the engine.

 

[Gary Allan]

What is he? Is he a 3k/3m type ..extended drain type...short trip or highway commuter?

It would make a difference on what I would use.

 

[Fuelrod]

Those old Rambler Motors are not to fussy about oil..Look on the can for the words "Motor Oil"

 

[MarkC]

I'm currently using Chevron HM 10W30 in my 96 Cherokee, and it runs great with 105K, no leaks, no consumption.

 

[brian]

I run Mobil Delvac 1/Truck & SUV 5w-40 year round with excellent results. This oil will hold up well for 10-15Kmi or more which is nice because I do a lot of highway driving. Also when pulling out small trees in my yard I feel more comfortable knowing there is 75w-140 in the axles and 5w-40 in the engine. Nobody seems to see a reduction in fuel economy with a xw-40 or an increase switching down to a xw-30. If I used the vehicle around town or lots of short trips in the winter a 0w-30 or 10w-30 would probably be my choice. These engines seem to last 200-300Kmi with mininal work so anything is probably overkill.

The automatic tranny used in recent Jeep 4.0's (like my Cherokee) is the Aisin-Warner AW4 (used in Toyotas) so it should be pretty reliable. Cherokee owners with Dana 35c rear axles proabbly need to pay more attention to that than the engine oil they use.

 

[Brett Miller]

That's exactly why I put Amsoil Severe Gear in my wife's Jeep axles.

 

[Gary Allan]

quote:

---

Nobody seems to see a reduction in fuel economy with a xw-40 or an increase switching down to a xw-30.

---

My only exception to that statement, brian, is in regard to dinos and lower ambient temps. In a synth ..I think you're 100% correct. My son lost a buttload of mpg using a 15w-40 in the winter. The oil takes too long to warm up and is so much thicker than the D1 he had in before. This is where temps span from (maybe) single digits to the teens. It was solved by using a H20/oil oil heat exchanger.

 

[JeepZJ4.0]

Go with a 10w40. A high mileage 10w30 is pretty good too since its a thick 30wt.

 

[brian]

Gary,

Wouldn't it have been cheaper to put synthetic in the engine rather than fit a heat exchanger? I reckon for experimentation the cost was not a big issue?

Brian

 

[Gary Allan]

Not really. The exchanger was $36 delivered off ebay ...plus the advantage is for life. The faster you get to operating temp, the less you tax your fuel economy.

This was, btw, an experiment comparing 15w-40 and 5w-40 for 7500 miles thru the winter. We had both been using Delvac 1 and I switched to Rotella T synth and he to Delvac 1300. Fuel economy on my son's Cherokee was the only issue. No start up or other type complaint was noted. Fuel economy dropped from about 18 for his 16 (approx) commute to around 12. It was almost totally restored with the exchanger due to the rapid warm up of the 4.0 coolant allowing the oil to thin much faster. If left unchecked, the condition would have paced the costs of the exchanger and the D1 costs.

That's why I asked what the service duty of the jeep was and what kinda of "oil guy" the owner is. If it's a relatively short trip commuter, the oil never reaches anywhere near its 100C visc. Hence a 30 weight may work just as well as a 40 weight. A 10w-40 may do fine ..but not if he's into extended drains (or it's a synth).

 

[brian]

In my Cherokee fuel economy has been all over the place since the middle of October, one tank its 16.6 the next it might be 18.5. I'm not sure why. I adjusted the rear drums back then because one side was "clicking" (even with the clicking the fuel economy was 18-18.5). I wonder if one of them intermittantly sticks? But I don't see any wear of the shoes or feel heat on the drums. I wonder if the economy change has to do with any changes in fuel formulation in mid October? At the time I also changed the oil (Delvac 1 -> Lubro Moly 5w-40), T-case fluid (Mobil 1 ATF -> Mobil 1 ATF), and air filter (K&N -> WIX paper). One by one I put everything back - K&N, Delvac 1, but the fuel economy still varies more than I remember it. Maybe my memory is not all that good?

-brian

 

[JeepZJ4.0]

I should of said, I use Mobil 1 0W40. My gas mileage went up, as well as driveability compared to the 15w40.

 

[MarkC]

Gas mileage on my Cherokee (5-speed) has always been fairly constant, never less than 18 in mostly city driving, and up to about 24 on a long highway trip if I keep the cruise control on and stay below 80 mph. I've always used a 10W30, except for one OCI with Delo 15W40 late last summer. Noticed no difference in MPG or anything else.

 

[Pablo]

Amsoil 15W-40.