10w-40 in Jeep 4.0

[Redhawk454]

I want to run 10w-40 for my next OCI in my 2006 Jeep wrangler rubicon 4.0

Owners manual recommends 10w30 for decent cold starting and fuel economy but I want to switch to 10w-40 from now on.

I don’t care about fuel economy, I just want my 4.0 to last as long as I can..

4.0 has a little 150k mile.

Is it a bad idea?

 

[joegreen]

No it’s not a bad idea. 10w40 will work perfectly fine with no issues

 

[Redhawk454]

Thanks

 

[FCD]

The 4.0 is an old school design that is not picky at all about oil, you could probably even run a 15w40 HDEO

 

[atikovi]

Owners manual recommends 10w30 for decent cold starting and fuel economy but I want to switch to 10w-40 from now on.

Both being 10W, cold starting will be the same.

 

[nwjones18]

10w-40 will be just fine.

 

[Chris142]

10w40 is in mine right now.

 

[thescreensavers]

The 4.0 is an old school design that is not picky at all about oil, you could probably even run a 15w40 HDEO

Being in S.FL thats what I run year around, 15W40 is cheap.

 

[addyguy]

Buy a cheaper and slightly stouter 15W-40 for that 4.0.

 

[JavierH19]

No problem. But buy either cheaper or better 15w-40 or similarly priced QS 5w-40.

 

[jeepman3071]

10w40 won't make it last any longer vs 10w30. There is a whole thread on the Jeep Strokers forum site where they did UOA comparisons on 30w vs 40w oils and there was little difference between them. With a 2006, your main concern with that engine is the oil pump drive gear assembly (OPDA) which is an issue on 2005 and 2006 4.0L engines.

 

[HoosierJeeper]

Won't be an issue. ran it in my 96 XJ!

 

[AZjeff]

There is a whole thread on the Jeep Strokers forum site

Have you tried jeepstrokers.com lately?

Is there a valid reason for me to run -40 oil in the new-to-me 4.0 with 115k miles?

 

[kschachn]

10w40 won't make it last any longer vs 10w30. There is a whole thread on the Jeep Strokers forum site where they did UOA comparisons on 30w vs 40w oils and there was little difference between them. With a 2006, your main concern with that engine is the oil pump drive gear assembly (OPDA) which is an issue on 2005 and 2006 4.0L engines.

A UOA isn't going to measure wear and provide comparative oil quality.

 

[chainblu]

Personally, I'd be surprised if 10w40 gave you any more measurable longevity (over 10w30), but if it makes you feel better go for it.

 

[sw99]

I would run the lowest price quality 10w30 and not even worry about the 242.

 

[jeepman3071]

Have you tried jeepstrokers.com lately?

Is there a valid reason for me to run -40 oil in the new-to-me 4.0 with 115k miles?

I haven't been on that site in years, but I don't really see a reason why a 40 would work better or worse.

 

[jeepman3071]

Personally, I'd be surprised if 10w40 gave you any more measurable longevity (over 10w30), but if it makes you feel better go for it.

Either way the body of the vehicle will rust out long before a measurable difference is seen. I'd be more concerned about startup wear in colder climates.

 

[blufeb95]

What climate are you in? Are you having any consumption issues or anything that you need to go thicker? I'd probably stick with a quality 10W30 or 5W30 synthetic if you live in a colder climate, and use the oversized Fram PH8A size filter or equivalent for less restriction.

 

[Redhawk454]

I’m in southern IA where we can get those cold winters..

Someone I know said not to use synthetic oil in a 242 since the engine was designed in 1962 and because the tolerances are greater, synthetic oil will cause leaks since it’s smaller on a molecular basis than conventional.