0W-30 in a Grand Cherokee ZJ 5.2 318 Magnum

[OlDirty]

Hello,
I found this website, which seems to be one of the #1 addresses concerning oil questions, especially for me it is perfect, because the Grand Cherokee ist quite rare in europe (germany).
So my question is, whether it is okay to fill 0W-30 into the mentioned engine, or might it be bad for it.
I already read, that those old iron-block engines need thicker oil, like 10W-40.
But I thought, that it makes sense to use this one, because I often do short trips of about 3-4 miles into next town.
It´s this one: Mobil 1 Fuel Economy 0W-30

 

[simple_gifts]

What year, how many miles on your ride.

Modern "Iron Block" engines have been using 30 weight oils for 30+ years.

 

[Sam_Julier]

What oil grade is specified?

 

[OlDirty]

Oh sorry, it´s a 97´Grand Cherokee ZJ with 204.000km, that´s about 127.000 miles.
Manual says: SAE 15W 40 or 10W 40 with API SG, SG/CD, SH, SH/CD and Energy Conserving II or CCMC G4

 

[redbone3]

I spent 8 years in Germany and many miles on the autobahn. If you drive like the typical German, you need the 40 weight oil.

 

[Flareside302]

Mobil 1 0w40 would be my go to

 

[OlDirty]

There is another deal right now, where I can get Mobil 1 Turbo Diesel 0W-40 for just 11$. I know, it´s diesel oil, but often there is no real difference between gasoline and diesel oil. Don't know how it is regarding this one...
You think this one would be better?

 

[440Magnum]

The engine in that Jeep is one of Chryser's finest- the 5.2 (Liter) is the 318 (cubic inch) smallblock that has its roots back in the late 1950s. Tough, reliable, simple engine, even in "Magnum" form of the 1990s with revised heads and fuel injection. I had an earlier 318 that I ran to over 400,000 miles, and my father had a Magnum like yours that he ran to well over 250,000 miles- and we used 10w30 or 5w30 exclusively in those (0w30 was not around when we owned them). And we live in Texas with 100F summers and rarely much below freezing in the winter.

A 30-grade oil like 0w30 is fine for the 5.2, but be aware that it runs a relatively low oil pressure in Magnum form with stud-mounted rockers and through-the-pushrod oiling (this is what your engine has- the earlier versions had rocker shafts and oiled the valves through the rocker shaft). ~40-50 PSI is common, where as over 60 PSI was common with the older oiling layout. This means that you might get oil pressure light flicker at idle with a thin oil. 0w30 wouldn't normally cause that, but I wouldn't go any thinner.

As others have said, a 0w40 oil as is common in Europe would also work very, very well in that engine. Many people over here also use diesel-rated oils in these engines as you suggested- I see no problem with that. For many years it was spec'd for 10w40 oil in hot climates before 10w40 oil fell out of favor in the late 70s in the US. But it was primarily spec'd for either 10w30 or 5w30 through the majority of its years in production.

 

[SLATRON]

go for the Mobil 1 if manual calls for a 40 oil and driving crazy fast there. but the 30 should be okay as well, the manual was written when thicker oils were spec'd and 0w was rare. both good oils imo

 

[OlDirty]

That´s a perfect answer! Thanks a lot

Now I feel save to make that purchase. I also get this one for 11$, which is very, very cheap. Normally I would have to pay double of that.
Always good to hear from somebody who owned the same engine and has a lot of experience with it.
Thank you guys!

 

[Clevy]

I had a ram with the magnum 5.2 engine. I used whatever cheap 5w-30 I could find and that truck was driven like a truck,full load of tools under the cap and pulled a trailer full of material half the time to the job sites.
The other half of the time it pulled a trailer full of scraps to the dump.
I got sideswiped with over 400k on the odo and that truck still started first turn. It had eaten 1 tranny by then though but the second was still pulling fine.
The 318 even in magnum form is still a legendary 318 and on this side of the pond they are just as durable as the chev 350 and the ford 302.
You'll be fine with a 0w-30,or a 40 grade. They aren't picky so you don't need to be either.
I abused that truck to no end and it came back for more every day. I loved that truck.

 

[dlundblad]

The 5.2 specs 15w40? Is that just a European thing or did the US ones call for that as well?

My mom had a 95 Zj with the 5.2.. I sure miss that thing.

 

[VNTS]

The magnums in the US called for 10w-30.

If he opts for 0w-40 TDT, he would be fine.

The only problems these engine have is the blown manifold plenum valley gasket.

Fix is to remove the intake and install a Hughes plate.

Other than that, change the oil and they will easilly run 250-300K miles.

 

[OlDirty]

I forgot to mention, that I use LPG instead of gasoline (gasoline just till the engine reaches 40 degrees celsius). Does that make any difference?

 

[440Magnum]

Originally Posted By: OlDirty
I forgot to mention, that I use LPG instead of gasoline (gasoline just till the engine reaches 40 degrees celsius). Does that make any difference?


LPG is easier on oil than gasoline. No worries.

 

[OlDirty]

Originally Posted By: 440Magnum
LPG is easier on oil than gasoline. No worries.

What does that mean? Less chemical reactive?

 

[Clevy]

Originally Posted By: OlDirty
Originally Posted By: 440Magnum
LPG is easier on oil than gasoline. No worries.

What does that mean? Less chemical reactive?



LPG burns cleaner,so the oil itself will never go black. I had a propane powered work van for years and one of my ford cube vans is a propane/gas dual fuel.
The oil lasts much longer in service because propane burns cleaner therefore the oil retains its tbn for much longer.
I don't think there is any sulfur in propane so no sulfuric acids to combat.
The oil will still lose its viscosity over time however tbn is far less of a concern using propane as fuel.
You can easily double the oil change interval because tbn will last much longer.

 

[jamesyarbrough]

Originally Posted By: OlDirty
Oh sorry, it´s a 97´Grand Cherokee ZJ with 204.000km, that´s about 127.000 miles.
Manual says: SAE 15W 40 or 10W 40 with API SG, SG/CD, SH, SH/CD and Energy Conserving II or CCMC G4


See guys we are the only ones in the world using thin oil. Its a conspiracy! Thats why im not on the thin train.

Oldirty a 0w40 or 0W30 would be just fine. Folks here in America put hundreds of thousands of miles on them with 5&10w30 and 10w40.

 

[OlDirty]

Thank you

Originally Posted By: VNTS
The only problems these engine have is the blown manifold plenum valley gasket.

Fix is to remove the intake and install a Hughes plate.

That´s an issue I experience... when I have enough time and money, I will fix that with the Hughes plate (or any similar one, available in Germany)

 

[440Magnum]

Originally Posted By: OlDirty
Originally Posted By: 440Magnum
LPG is easier on oil than gasoline. No worries.

What does that mean? Less chemical reactive?


Less carbon blow-by, no fuel dilution. Same amount of moisture, so acidity creep is probably similar.