Jeep 4.0 winter oil

[willy peter]

I've got a 2001 Jeep Tj with a 4.0 with 30K on it. What oil should I put in for the winter? I have used Pennzoil Conventional 10w30 over the summer, but the manual says 5w30 can be used in the winter. Is synthetic worth it even if I am still going to change it every 3K miles? BTW I live in northern Michigan so it does get pretty cold around here, averaging in maybe the 20's.

 

[KJA426]

A synthetic 5w30 would probably be ideal for your winters but a conventional 5w30 would still work. I'd go for SM G4 Mobil 1 5w30 and do your regular change intervals.

 

[Bob Miller]

Havaline 5w30 or motorcraft 5w30 should be fine for winter.

 

[willy peter]

Is there any benefit to synthetic if I am not going to use an extended OCI? My local Autozone has recently come out with a new "autozone brand" synthetic which isn't much more expensive than regular oil. Is this stuff truly synthetic or is it just to lure in people who want synthetic but don't want to spend a lot?

 

[Eddie]

I ran my 4.0 for 197,000 miles on Mobil 1 10w30 all year in northern ILL. and never a problem. The Jeep ws in an unheated garage over night which may have helped.

 

[MarkC]

used oil analysis on the 4.0 with Mobil 1 10w30 have shown high iron wear, so I wouldn't use that weight or lighter Mobil 1 in this engine.

 

[MNgopher]

A 5w30 conventional will work fine for your winter application. A 10w30 would likely "work", but the 5w30 will work better. Don't waste your money on a synthethic if you are going to stick to a 3000 mile oil change. The synthetics arguably offer some cold start benefits, but the 5w30 conventional will work just fine in your climate.

 

[willy peter]

So does anybody know anything about this autozone brand synthetic?

 

[99]

conventional 5w30 or 10w30 will be fine. You could even go with a synthetic 5w40 like Shell Rotella T Syn or Mobil 1 Truck and Suv if you wanted a synthetic oil. I believe the 5/10w30 synthetics are too thin for the 4.0.

 

[99]

quote:

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Originally posted by willy peter:
So does anybody know anything about this autozone brand synthetic?

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Never heard of it. I personally wouldn't buy it because I don't trust house brand oils.

 

[MNgopher]

quote:

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Originally posted by 99:
conventional 5w30 or 10w30 will be fine. You could even go with a synthetic 5w40 like Shell Rotella T Syn or Mobil 1 Truck and Suv if you wanted a synthetic oil. I believe the 5/10w30 synthetics are too thin for the 4.0.

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Currently running 10w30 Citgo Synthetic in my '88 XJ. Check out the UOA posted under myname if you think a synthetic 10w30 is too "thin" for a 4.0l.

 

[Jerry]

There was some postings of used oil analysis showing 40 weight having lower numbers than 30... search button

 

[Gary Allan]

Some appear to do okay with 30 weights. MNgopher appears to have run both ways on it and, at least in his service/climate/etc ..the 30 weights do well. They also do well for short trip types. They didn't do well on my wife's 99. Her Fe dropped to about 30% of her 30 weight reading with using a 40 weight. It tends to point to viscosity/oil temp as the cause. If you don't really ever get up to temp ..your 30 weight isn't a 30 weight. As with everything else ..YMMV.