rotella in a jeep

[coralman]

98 jeep grand cherokee 4.0 engine. I spend a great deal of time on jeep forums. a lot of jeepers run rotella 15w40, they say for the high zinc content, since the motor is a flat tappet design. This oil is designed for diesels. I was considering running the 10w30 version. But I see they offer the T5 synth mixture as well. I've worried about the synth in a high mileage motor creating seal leaks, and don't know that the T5 has the additive package needed for the tappets. Any advice is appreciated. Just a daily driver, no towing or offroad. Reside in northern florida where the temps are hot in summer and cold about month these days.

 

[Zaedock]

10W30 would be fine. There's no need to run anything special in a 4.0L. The valve springs are low tension so extra ZDDP is not required.
FWIW, I run group III 5W30 in my trail Jeep and its fine getting the snot beat out of it.

 

[Donald]

I am running T6 in my 4.0 engine, because I wanted to try something other than PU and I have lots of T6 because of my Cummins diesel. A UOA was sent out recently, see how it comes back.

 

[SwampSurvivor]

T6 or T5 would be an excellent oil for a 4.0.

If I lived in a warm climate, I wouldn't hesitate to run 15w-40 in a 4.0.

 

[fins]

I have had three Jeeps over the last 15 years..........I ran Rotella 15-40 in all of them.
Sometimes I would mix 0-40 with the 15-40 for winter.

I just changed the oil a few days ago in my 2005 LJ wrangler........I have switched over to QS Defy with added zinc that is suppose to be good in flat tappet engines.

Since the trends seem to be towards thinner oils I even went with 5-30......maybe I am imagining it, but the jeep seems to idle smoother and more quite.

 

[salv]

I loved Delo 15w40 in mine during the spring and summer months.

 

[Chris142]

Mine seems to lose some power with 15w40. Plus flat cams are very rare considering the amount of jeeps running around on sn oil. Ive gone back to regular 10w30.

 

[renegade_987]

Most people like Rotella T6 5w40 in the 4.0's, but 10w30 will be fine too. No real need for a 15w40

 

[440Magnum]

Originally Posted By: coralman
98 jeep grand cherokee 4.0 engine. I spend a great deal of time on jeep forums. a lot of jeepers run rotella 15w40, they say for the high zinc content, since the motor is a flat tappet design. This oil is designed for diesels. I was considering running the 10w30 version. But I see they offer the T5 synth mixture as well. I've worried about the synth in a high mileage motor creating seal leaks, and don't know that the T5 has the additive package needed for the tappets. Any advice is appreciated. Just a daily driver, no towing or offroad. Reside in northern florida where the temps are hot in summer and cold about month these days.


The 4.0 has very mild valve springs so the contact pressures on those flat tappets are way, way lower than a 1960s big-block V8 in a muscle car. It doesn't really NEED high ZDDP levels once its broken in (and by the way, its not the zinc that does the protecting, its the phosphorous bound to the zinc...).

But also there's no arguing the fact that the 4.0 runs extremely well with a heavier grade diesel-type heavy duty oil as has been proven by dozens of oil analyses. I use T5 synthetic in both of ours- its fairly cheap, readily available, cleans well, and the engines work well on it. Why not use it?

 

[KCJeep]

Rotella is a great match for the Jeep, but the 15w40 is needlessly thick IMO, even the Rotella 10w30 is quite thick being on the top end of 30 grade.

The full conventional 10w30 or the T5 10w30 would be my pick. If you want a 40 grade the full syn T6 5w40 would be much superior to 15w40. JMO.

 

[ddtmoto]

QS Defy in the correct weight would be the ticket. Very quiet and smooth running 5w30, 10w40 and 10w30 that I have been using in some of my units...

 

[coralman]

Thanks for all of the replies and advice! I appreciate it.

 

[MKZman]

I have been looking for a 10W-30 and Rotella just seems to be a good deal -- inexpensive, readily available at many places, part synthetic, and all the right API specs.

 

[JR]

If you want zinc and phosphorus go with redline 4stroke kart 5w-20 oil.
phoshorus, avg PPM 2500
zinc, avg PPM 2400
i rann it in a intec 206 i had hopped up some, engine builder thrown it into the deal.

ken

i have had a couple 4.0's. i used hdeo or vr1.
Vr1 and many hdeo's can be had easily in 10w-30.

 

[KCJeep]

Do not put 5w20 in a Jeep 4.0.

 

[Zaedock]

Originally Posted By: JR
If you want zinc and phosphorus go with redline 4stroke kart 5w-20 oil.
phoshorus, avg PPM 2500
zinc, avg PPM 2400
i rann it in a intec 206 i had hopped up some, engine builder thrown it into the deal.

ken

i have had a couple 4.0's. i used hdeo or vr1.
Vr1 and many hdeo's can be had easily in 10w-30.


That level will cause more harm than good. You can't compare a 5.5HP single to a 4.0L I6.

 

[Garak]

Originally Posted By: JR
If you want zinc and phosphorus go with redline 4stroke kart 5w-20 oil.
phoshorus, avg PPM 2500
zinc, avg PPM 2400
i rann it in a intec 206 i had hopped up some, engine builder thrown it into the deal.

That amount of ZDDP is corrosive. If the Jeep is racing and has its oil changed every race and gets a new engine on occasion, go for it.