Oil weight for 4.0L-- 15W40 in Australia?

[winkosmosis]

My XJ has some slow leaks, so I'm considering switching from the recommended 10W-30 to 15W-40. A lot of people use this weight, especially since Shell Rotella T has extra ZDDP which is apparently good for the tappets-- Yet I'm still not sure I want to disregard the manual.

BUT, I remember reading somewhere that in Australia, Chrysler recommends 15W-40 for the 4.0L because Down Under common wisdom is that thicker oil protects better.

Whatever the reason, if Chrysler says it's OK, I would have no problem trying it. Can any Aussie Jeepers confirm what oil weight your manual recommends? All I can find on the internet is rumors and hearsay, but no one directly quoting the manuals.

Edit: BTW, I live on Maui and probably the lowest temp the XJ will be started at is mid 60s. No colder than Australia I believe.

 

[alosix]

Quaker State used to make (might still) a 'Truck' blend that was 15w40. Ran it through my TJ for a change or 2. Only difference I noticed was it was a bit slow to start when it was cold out.

FWIW, I'm @ 146k and its run Mobile 1 Syn 10w30 since its 3rd or 4th oil change. It has a seep @ the rear main and one near the cam position sensor. The amount hasn't changed in ages though.

Edit: Also.. I used to live where it actually gets cold out your 60 degree bottom should be fine for a little thicker oil.

 

[wjeeper]

Cant tell ya what the Jeep manuals specify for the Australian market but I can tell you I use to run 15w-40 Shell Rotella 9 months out of the year in my 4.0. No ill effects that I am aware of in the 50,000ish miles I put on with it in. In fact its what I run in my both 2.5L four poppers now. (it was cheap since our farm gets it in the 55 gallon drum)

I think that running a heavier weight isn't a bad thing at all in these motors. It seems to hush some of the valvetrain clicking. But in the same breath I think the 4.0 really isn't that picky what you feed it as long as its kinda close.

 

[DaJudge]

I run 10-40 in my XJ. Better for cold starts then the 15-40 but holds up great in the heat of the southwest.

 

[winkosmosis]

10W-40 isn't any thicker than 10W-30 when cold right? I assume I'd need the 15W-40 to combat leaking

 

[DaJudge]

10W-40 isn't any thicker than 10W-30 when cold right? I assume I'd need the 15W-40 to combat leaking

You are correct, however using a thicker oil to combat leaking is not a good idea. Fixing the leaks would be much better. You will be putting more wear on components during cold starts.

 

[alosix]

10W-40 isn't any thicker than 10W-30 when cold right? I assume I'd need the 15W-40 to combat leaking

I think you'll need new seals to combat the leaking.. That or wait WAY too long to change the oil to let enough crud build up in it to block the leaks

A buddy of mine has gone through this with his XJ. First switched off of synthetic, then went thicker in the hopes it would quit leaking. It still leaked. It might leak a little slower now, but it still leaks.

 

[winkosmosis]

Well I think my distributor seal is leaking and the valve cover gasket is also wet but not dripping. I don't think I can do the job and mechanics here are terrible and expensive. I literally can't afford getting seals replaced but I'm about to do an oil change this weekend.

 

[alosix]

Well I think my distributor seal is leaking and the valve cover gasket is also wet but not dripping. I don't think I can do the job and mechanics here are terrible and expensive. I literally can't afford getting seals replaced but I'm about to do an oil change this weekend.

I have at least the distributor seal leak.. haven't looked at my valve cover lately If I ever get around to replacing it I'll post up how much work it was.

I doubt it can be much.. there isn't a whole lot holding it on there.

Jason

 

[winkosmosis]

I have at least the distributor seal leak.. haven't looked at my valve cover lately If I ever get around to replacing it I'll post up how much work it was.

I doubt it can be much.. there isn't a whole lot holding it on there.

Jason

There's a lot of stuff in the way though. Plus I'm clumsy. I broke my oil pressure sensor the last time I changed my oil filter

 

[alosix]

There's a lot of stuff in the way though. Plus I'm clumsy. I broke my oil pressure sensor the last time I changed my oil filter

Ah yeah.. XJ much more crowded in that area than my TJ is... Well until I stuff a donaldson air filter into that area to hook to the snorkel

 

[winkosmosis]

How does viscosity scale with temperature?

For example, the 15W isn't any thicker than a 10W freezing temperature right?

My running temperature is about 200-210F. At that temp is the 40 a thicker oil than a 30 at 192F? (which is what I usually got to on cold days in Houston)

 

[troy]

I've got a 100K using shell rotella 15w40 on my XJ 4.0. I'm in MN, so I switch to Rotella 5w40 around December - February. I have been caught with 15w40 in temps down to -20F. It did not like it, but still started.

I did notice a little less leakage, lifter ticking was improved, and oil pressure came up from 5-10 psi to 20-40. Jeep now has 245K and still feels like plenty of power. Almost zero oil consumption between changes at 5K intervals.

Just my experience, I'm not a oil brand or weight snob. Many inline sixes will run forever in very poor conditions and maintenance. My thought process is that this engine is an "old" tech engine and does not benefit from low viscocity oils like the tighter newer engines. In the wifes '07 Mazda, I've run 5w20 synthetic since new.

 

[winkosmosis]

I found a viscosity chart. http://www.widman.biz/uploads/calc-graph.html

10W-30 at 195F (90C): 13.2
10W-30 at 210F (100C): 10.4

15W-40 at 195F: 20.0
15W-40 at 210F: 15.6

 

[winkosmosis]

I got some Chevron Supreme 10W-40. But I'm scared to veer from Chrysler's recommendation. I really wish some Australian would confirm that 40 really is OK