You can prolly use 15w40 down to freezing without any worries. If the engine does seem to turn over a bit too slow you could always try a good quality 10w40.
Jeeps 4.0 OIL
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You can use a 15w-40 in just about any temp. My son used it last winter down to the single digits. The 4.0 didn't care. He was churning 70+ weight for a few miles ..but the engine could care less. The only thing you're doing is wasting a little more energy than the 4.0 does on its own.
If you want the thinnest stuff that will do the job, get a 10w-30 that's on the heavier side. Swap it out every 6 months. If you do over a certain number of miles a year, consider a synthetic. I would not recommend any 5w-30 in this engine although many do use them without any issues.
If you want the thinnest stuff that will do the job, get a 10w-30 that's on the heavier side. Swap it out every 6 months. If you do over a certain number of miles a year, consider a synthetic. I would not recommend any 5w-30 in this engine although many do use them without any issues.
See? Told you Gary was on the case!
Don't use Mobil 10W30. Try Havoline, Pennzoil,or Castrol.
I don't know about Mobil 10W40.I just advise against the Mobil 1 10W30 because the UOA's I see here show much higher wear rates than almost anything else,and every 4.0 I've heard that ran it sounded louder than normal.
You could do the T&SUV 5W40 if you want to spend the money.
I used the regular Castrol 10W30 for my 4.0 when I lived in NC, Regular Chevron 10W30 after I moved to Seattle, and for the past year the HM 10W30. You might not find Chevron in FL, but Havoline is about the same, though Chevron says it's a bit better in the add pack.
If you look through the Jeep 4.0 UOA's you'll find some good stuff.
I was impressed with aztec's UOA on Valvoline Maxlife, which was the best I've seen on this engine.
The HM has cST of 12 @ 100, while the regular sports a 10.8. The 10W40 regular is 14.8, so as you see, the HM is a good place in between. Starts out with a higher Base number as well, 7.9 rather than 7.4.
You could do the T&SUV 5W40 if you want to spend the money.
I used the regular Castrol 10W30 for my 4.0 when I lived in NC, Regular Chevron 10W30 after I moved to Seattle, and for the past year the HM 10W30. You might not find Chevron in FL, but Havoline is about the same, though Chevron says it's a bit better in the add pack.
If you look through the Jeep 4.0 UOA's you'll find some good stuff.
I was impressed with aztec's UOA on Valvoline Maxlife, which was the best I've seen on this engine.
The HM has cST of 12 @ 100, while the regular sports a 10.8. The 10W40 regular is 14.8, so as you see, the HM is a good place in between. Starts out with a higher Base number as well, 7.9 rather than 7.4.
I've had very good results with 40W's and high 30W's in both 4.0's and my 2.5L TJ.
Here's my bro's last UOA on Schaeffer 15W-40 Blend. http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=001920
I've since switched his TJ to Mobil 1 5W-40 and it just seems his motor runs pretty **** smooth compared to the 10W-30 we first ran in it. A HDEO 15W-40 in your climate will work fantastic and these oils have a great additive package to boot. Change em every 6 months and be done with it. I honestly don't think it really matters in these designs. I've seen guys well over 150K on cheap 10W-30. I personally think they run smoother on 40W's and the UOA's show a lower wear rate but in the scheme of things it probably does not matter.
Here's my bro's last UOA on Schaeffer 15W-40 Blend. http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=001920
I've since switched his TJ to Mobil 1 5W-40 and it just seems his motor runs pretty **** smooth compared to the 10W-30 we first ran in it. A HDEO 15W-40 in your climate will work fantastic and these oils have a great additive package to boot. Change em every 6 months and be done with it. I honestly don't think it really matters in these designs. I've seen guys well over 150K on cheap 10W-30. I personally think they run smoother on 40W's and the UOA's show a lower wear rate but in the scheme of things it probably does not matter.
Hello, I'm might be getting a wrangler and currenty we have a 98 cherokee(4.0 170K).I was advised here a few months back that 40wts are idea in these engines or a thick 10w30s. I used val Maxlife 10w30 for a while and was quiet and ran good, now i'm using Delo 15w40 and all is good. Question is can i use this oil in our mild Florida winters 40- 60 deg (cold start)?
What should i use in a new wrangler 4.0? Will a thin 10w30 be good so it will cause more waer and break in faster? Mobil 5000 10w40/ delo 15w40?
BTW the cherokee does short trips trffic a bit of highway,daily commute stop and go,20miles trips or less.
What should i use in a new wrangler 4.0? Will a thin 10w30 be good so it will cause more waer and break in faster? Mobil 5000 10w40/ delo 15w40?
BTW the cherokee does short trips trffic a bit of highway,daily commute stop and go,20miles trips or less.
In Florida you can use Delo 15W40 all the time if you like. but... you don't always need a 40 weight in the 4.0. If I were you, I think I'd use a heavy 10W30 in the Cherokee.
As for the Wrangler, a 10W30 isn't going to cause more wear than a 40 wgt.
I wouldn't be mixing Mobil with Delo. If you want to mix, it would be better to stick with the same brand, Chevron or Havoline with the Delo.
Just what I think. I'd do some UOA's if I were you, and ask Terry what he thinks.
I'm sure Gary will have better advice than me.
As for the Wrangler, a 10W30 isn't going to cause more wear than a 40 wgt.
I wouldn't be mixing Mobil with Delo. If you want to mix, it would be better to stick with the same brand, Chevron or Havoline with the Delo.
Just what I think. I'd do some UOA's if I were you, and ask Terry what he thinks.
I'm sure Gary will have better advice than me.
Where's that UOA on the jeep using the Delvac 5W-40...that was sweet!
Seeing as you are from south Florida, you can stick with the 15W40 year round. If you'd like, you can drop down to a 10W40 in the "winter", but I don't think it's really necessary. Enjoy that weather....it's 15 and dropping where I'm at.
As for a 15W40 down to single digits, I'd err on the side of caution with that one, but that's just me. If you are seeing temps that low, I can't even see why someone would go that thick in a 4.0. A 5W40 would be a better choice if a 40wt is what you absolutely had to have. For the majority of us folks that see a real winter, 10W30 or even 5W30 would be a MUCH better alternative and make life MUCH easier on the engine during those brutally cold starts.
As for a 15W40 down to single digits, I'd err on the side of caution with that one, but that's just me. If you are seeing temps that low, I can't even see why someone would go that thick in a 4.0. A 5W40 would be a better choice if a 40wt is what you absolutely had to have. For the majority of us folks that see a real winter, 10W30 or even 5W30 would be a MUCH better alternative and make life MUCH easier on the engine during those brutally cold starts.
5W30 TropArtic in a 85 2.5 Cherokee 130K. Seems to work good. Now about 2f. I had 5W30 M1 in it and it loved it. But it started leaking prit near everywhere. So I went to cheap stuff. I've had this Jeep since 2000. Pd $150. for it, bad AX 5. Now with salvage yd tranny I get around in the snow easier. It is my winter beater. Don't drive it in the summer. I put some 10w30 gtx in when i first got it, but since it has seen nothing but 5w30. Engine is seemingly bullet proof. 
. I love cast iron at -30f.
J.
. I love cast iron at -30f.J.
"As for a 15W40 down to single digits, I'd err on the side of caution with that one, but that's just me."
The other day I started up the 1.6L Integra after it had sat around all afternoon without the engine block heater plugged in... the temp, 2F.
Oh the humanity... Delvac 15W-40 was not its friend. It loves the stuff when it's warm out, but we haven't had a chance to change it out yet.
So yeah, single digits with the 15W-40 is not the best of times.
The other day I started up the 1.6L Integra after it had sat around all afternoon without the engine block heater plugged in... the temp, 2F.
Oh the humanity... Delvac 15W-40 was not its friend. It loves the stuff when it's warm out, but we haven't had a chance to change it out yet.
So yeah, single digits with the 15W-40 is not the best of times.
I currently use Amsoil 10W40/Baldwin filter in my wifes 96 Cherokee with 150K on it. Started this morning with no problem whatsoever at -5 or so. No added noise, no problems. I don't think a 5W would make much difference.
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No noises out of our jeeps (our TJ's and son's Cherokee) in the cold (usually a very limited time to the single digits ..if at all). The 2.5 does crank a littel slower in the below freezing temps, but that's about it. Currently all have 5w-40 synth ..either RTS or TSUV.
For those that care, we had our coldest overnight temp yet, 0F, and that's without the windchill factored in. This morning, the Jeep (97 4.0 TJ) made all kinds of racket for about 3 seconds with a 10W30, Mobil 5000 and a Purolator Premium Plus filter. Up till today it has been quiet on startup, but this very cold overnight freeze really stressed it. I would've NOT wanted to hear what it would've sounded like with a thicker oil in it. Had I known it would've gotten this cold this fast, I would've used 5W30 at my last oil change.
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I should restate my "slower cranking". My 2.5 hits on the 3rd "wrr" all the time ("wrr-wr-rr-wr). The 2nd "wrr" is slightly elongated in the cold. It's also elongated in the warm/hot weather, but the cranking event is quicker/shorter. My PCM was flashed before I took delivery and probably has an advanced timing curve that should be corrected even more. Since you can only reflash the PCM twice, I've not bothered to do it since the situation presents no operational issues. It's never had a 30 weight in it except for the factory fill so I can't say how it does with it in the below freezing temps.
This last week with several mornings below zero and sinlge digits, my 88 Cherokee 4.0l has been starting fine on Citgo 10w30 synthetic without any strange noises. Startup seems to be comparable to 5w30 dino and the Shell Rotella T Synthetic 5w40 I had been running in the past.
I do remember a few winters ago running Dino 10w30 and it was not a very happy camper in the cold weather. UOA bore out I wasn't doing the engine any favors!
I do remember a few winters ago running Dino 10w30 and it was not a very happy camper in the cold weather. UOA bore out I wasn't doing the engine any favors!
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