5w30 in a Jeep 4.0L

[Nick1994]

Well it sounds like it'll survive on the 5w30 I have in my stash if I keep the OCIs to the 3k mile/1 year I already do. Thanks guys.

 

[GMBoy]

Go ahead and use it up. It's still a 30wt at operating temp. I used to run mobil 1 10W/30 in my 2000 Cherokee Limited (XJ) 4.0L in summer and 5W/30 M1 in winter. No issues in over 100k miles. Only bad thing is I still wish I hadn't sold it!!

 

[dlundblad]

Its interesting to see the fuel economy hits noted with T6.

 

[Lex94]

PYB 10w30 and PUP 10w30 were the smoothest and quietest and with much better fuel economy in my testing...Even over the 5w30 grades.

Maybe one of you Jeep 4.0L people can try Royal Purple synthetic SAE 30.

 

[KCJeep]

They run fine on 5w30 they just tend to shear it close to a 20 grade by 3k miles which is not the best for the old Jeep 4.0, so keep the OCI's fairly short and you'll be okay with 5w30.

Optimum for a Jeep 4.0 is a top quality 10w30 (like PYB or Valvoline) or a slightly heavier 30 grade like Defy, Pennzoil HM or Rotella. A 40 grade that is on the thinner side also works well.

 

[84zmyfavorite]

I Currently have 7 Jeep Cherokees, 5 of which have the Jeep 242 4.0Liter Inline Six. These engines are Not a close tolerance engine, right out of the factory. The technology of these engines comes from the Sixties. They Live in Harmony with 10w oils when cold that thicken to a Thick 30 weight or Thin 40 weight when warm. The Flat feet of the lifters sliding over those camshaft lobes, .0025" clearance(at the tightest, from factory) between journals and bearings just Prefer and seem to work best with a 10w-30 ar 10w-40. Especially if there is a manual transmission behind a Jeep 4.0$ 5w-30 is Great below 20 degrees in the Jeep 4.0 though. Just not as good as a 10w above 20 degrees.

 

[jorton]

Originally Posted By: DoubleWasp
Use a 5/30 with better shear resistance.

Valvoline stays in grade.

 

[Kuato]

Originally Posted By: Nick1994
So I have always heard on here about how 5w30 and 0w30 are completely compatible in 10w30 applications. BUT, I recently saw on a thread where a couple people said to use 10w30 in a Jeep 4.0L, that it would shear down a 5w30.

Why is the 4.0L the only exception where it's recommended to not use a 5w30 in it? I ask because I have lots of Castrol GTX SynBlend 5w30 in my stash for my grandfather's 96' Cherokee with the 4.0L that I maintain and my brother has a 91' Cherokee with the 4.0L and he too has lots of the same oil in the same weight waiting to go in there. Also my grandfather's Jeep currently has the PurePlus Pennzoil Platinum 5w30 in it (it gets a yearly oil change, about 3-4k miles per year).

So, is it not very safe to use 5w30 in a 4.0L? What if it were for 5k miles?



While living in southern Virginia, I used 5w30 and 0w30* in my 2004 4.0 from when I bought it in 2008 until I traded it last year(post accident). Stellar UOAs with both.




* with one exception when I had some leftover Amsoil 10w30 that I used for a long trip, while towing, in up to 40 degrees (104F).

 

[niero]

Personally, I've always run Valv high mileage syn-blend at 5w30 or 10w30. I have had many recommendations on jeepforum.com saying 5w30 is just fine in the I6 engine, FWIW.

 

[Lex94]

Consider Pennzoil Gold 10w30 year-round. That would seem to be the sweet spot.

 

[84zmyfavorite]

There is a Pennzoil Gold 10w-30? Ive only seen 5w-30, better fire up the Ol Jeep and go huntin for some! That would be the SweetSpot,...for awhile.

 

[dlundblad]

I havent seen 10w30 Gold (Dexos Blend) either.

The Pennzoil 10w30 HM flavor is a blend however.

 

[Lex94]

Originally Posted By: 84zmyfavorite
There is a Pennzoil Gold 10w-30? Ive only seen 5w-30, better fire up the Ol Jeep and go huntin for some! That would be the SweetSpot,...for awhile.


I have to hunt it down as well...It is my next test oil after my current Delo 15w30 - which I had to travel 55 miles to find.