New to me High Mileage Jeep

[run2jeepn]

I just bought a 2011 Jeep Wrangler Unlimited with the 3.8L 4spd Auto. It has 160k miles on it and a very small rear main leak. Jeep runs smooth. I have non the service records. I believe I'm the 3rd owner of it. the 2nd owner only had it a 1yr and put 1000k miles on it. He changed the oil and put in 5w-20 synthetic with a Wix filter. The Jeep didn't burn any oil from what the last owner told me, but again he only pout 1000k miles in it in a year. So that doesn't tell me much. Jeep runs strong still.

My question is should I switch to 5w-30 or even 10w-30. Stay with synthetic oil?

Was thinking of switching to a slightly thicker oil and adding some Blue Devil Rear main sealer.

Not sure if it matters, but it has 37's and 4.88 gears. Has some added weight from bumpers, full size spare and hard top.

 

[Graham Piccinini]

I'd go with Mobil1 0W-40 and stick with it for the length of the ownership. That engine is pretty tough, but in conjunction with all other upgrades and increased load on the engine - M1 0W-40 may be a good idea, if you're keeping it for the long haul. As you most likely already know, this engine is a known oil burner, but if you keep it topped off - it will outlive the rest of the Wrangler.

 

[XCIDMigs]

OP Why are you not just using a synthetic HIGH MILEAGE oil of the jeep's OEM viscosity? You didn't tell us the location for use but I'm sure MOPAR has a slight variety listed. The old myth of using a thicker grade rated oil to combat leaks and burning is just nonsense and may actually add to the problem not to mention can worsen MPG.

More thoughts...

WHAT RIGHT OIL TO USE FOR JEEP WRANGLER 2011 3.8L

Greetings, I need some help with the following, the last time a local mechanic changed the oil of my "JEEP WRANGLER JK 2011 3.8L Gasoline" , he put in SAE 10W-30 synthetic brand by CAM2 Super Pro Max, API Service SN-RC ILSAC GF-5, the Manual says to use API certified 5W-20 meeting Chrysler...

bobistheoilguy.com

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[run2jeepn]

OP Why are you not just using a synthetic HIGH MILEAGE oil of the jeep's OEM viscosity? You didn't tell us the location for use but I'm sure MOPAR has a slight variety listed. The old myth of using a thicker grade rated oil to combat leaks and burning is just nonsense and may actually add to the problem not to mention can worsen MPG.

More thoughts...

WHAT RIGHT OIL TO USE FOR JEEP WRANGLER 2011 3.8L

Greetings, I need some help with the following, the last time a local mechanic changed the oil of my "JEEP WRANGLER JK 2011 3.8L Gasoline" , he put in SAE 10W-30 synthetic brand by CAM2 Super Pro Max, API Service SN-RC ILSAC GF-5, the Manual says to use API certified 5W-20 meeting Chrysler...

bobistheoilguy.com

.

From what I've read I get mixed results. I guess when the 3.8L came out it took 10w-30 and as time went. Dodge kept changing the oil from 10w-30 to 5w-30 and now since 2007 they put 5w-20. Guys have bought Mopar Crate 3.8L's and the Oil caps say 10w-30 on many of them. I also thought with the higher mileage and engine wear bumping the oil weight up would help? Thats why I'm asking, if I knew it all I would have never asked.

 

[Graham Piccinini]

OP Why are you not just using a synthetic HIGH MILEAGE oil of the jeep's OEM viscosity? You didn't tell us the location for use but I'm sure MOPAR has a slight variety listed. The old myth of using a thicker grade rated oil to combat leaks and burning is just nonsense and may actually add to the problem not to mention can worsen MPG.

More thoughts...

WHAT RIGHT OIL TO USE FOR JEEP WRANGLER 2011 3.8L

Greetings, I need some help with the following, the last time a local mechanic changed the oil of my "JEEP WRANGLER JK 2011 3.8L Gasoline" , he put in SAE 10W-30 synthetic brand by CAM2 Super Pro Max, API Service SN-RC ILSAC GF-5, the Manual says to use API certified 5W-20 meeting Chrysler...

bobistheoilguy.com

.

Worsen MPG? Lol... Read OP's post. I'm pretty sure the MPG is the last thing on his mind. The Jeep is upgraded with more weight on itself, and more weight on those 37"tires. All of that weight and upgrades put extra stress on the engine, which is why I still recommend M1 0W-40 (Plenty of UOAs available on this website, from a variety of vehicles, showing how great this oil is when it comes to minimizing engine wear). For a stock Jeep your blanket statement may have been applicable, but for a heavily upgraded unit all precautionary measures better be taken. Speaking of which - OP make sure to change the differential/transfer case/transmission fluids too. A coolant replacement would be a great idea as well. Assuming this will be a trail rig... And for the rear main - ATP AT-205 worked great for many engines. Some owners even use it in a spray bottle for all other rubber components on vehicles.

 

[ka9mnx]

Worsen MPG? Lol... Read OP's post. I'm pretty sure the MPG is the last thing on his mind. The Jeep is upgraded with more weight on itself, and more weight on those 37"tires. All of that weight and upgrades put extra stress on the engine, which is why I still recommend M1 0W-40 (Plenty of UOAs available on this website, from a variety of vehicles, showing how great this oil is when it comes to minimizing engine wear). For a stock Jeep your blanket statement may have been applicable, but for a heavily upgraded unit all precautionary measures better be taken.

That being said, 0w-40 has no benefit for his engine from what is spec'd from the manufacturer.

 

[benjy]

show your location for better recommendations as ambient temps are important!! they are known for rear main leakage + using a 5 or 10-30 oil helps. pick one even thrifty super tech synthetic thats almost as cheap as brand name conventionals

 

[ka9mnx]

From what I've read I get mixed results. I guess when the 3.8L came out it took 10w-30 and as time went. Dodge kept changing the oil from 10w-30 to 5w-30 and now since 2007 they put 5w-20. Guys have bought Mopar Crate 3.8L's and the Oil caps say 10w-30 on many of them. I also thought with the higher mileage and engine wear bumping the oil weight up would help? Thats why I'm asking, if I knew it all I would have never asked.

Each time a manufacturer back-spec's an oil grade they thoroughly test that oil in the engine. It's not a hap hazard decision. And, you are looking for a problem you don't know exists (high mileage engine needs thicker oil). I have 2 vehicles with over 250K miles that, at the next change, will be getting 0w-20 (they were back spec'd to 5w-20). If you are concerned with the rear main seal leak, try a HM oil as was suggested.

 

[jeepman3071]

The 3.8L doesn't care what is in it, it will drink all of it. I would use 5w30 and just keep it topped off.

 

[Graham Piccinini]

That being said, 0w-40 has no benefit for his engine from what is spec'd from the manufacturer.

Manufacturer/OEM recommendations are for stock applications. But here the Jeep in question has increased loads all around as compared to stock. If you think a 5W20 will protect against wear as good as Mobil1 0W40 in that 3.8L engine, then I'll be glad to attribute to a little test...
Test: I'll buy OP 1 UOA kit, and you buy 1 UOA kit. He'll use 1 after this run of 5W20, and he can use the second kit after a run of M1 0W40. OP supplies the oil, me and you supply the UOA kits, and we'll see which oil comes up with smaller "wear" numbers. Fair enough?

 

[tiger862]

Valvoline Advance Synthetic with Maxlife in 5w20. That engine doesn't care what grade is in it. There is so much misinformation but truth be told you keep an eye on the oil level it will last for years. The engine is under powered for the Jeep but with the gearing you have it will help.

 

[cb4017]

In my 08 JKU I ran 5w-30 almost from new. The engine just seemed quieter and happier with the slightly thicker oil. I used 5k OCIs and sent samples for UOAs on a regular basis. I even tried a run of M1 0w-40 once. Mine was still going strong at 110K miles when I had an LS 5.3 engine swap done.

The 3.8L engines in the JK use oil. Mine went through about a qt every 5k miles. They also seem to spin main bearings. Lots of reading at the JK Forums if you're interested.

 

[ka9mnx]

Manufacturer/OEM recommendations are for stock applications. But here the Jeep in question has increased loads all around as compared to stock. If you think a 5W20 will protect against wear as good as Mobil1 0W40 in that 3.8L engine, then I'll be glad to attribute to a little test...
Test: I'll buy OP 1 UOA kit, and you buy 1 UOA kit. He'll use 1 after this run of 5W20, and he can use the second kit after a run of M1 0W40. OP supplies the oil, me and you supply the UOA kits, and we'll see which oil comes up with smaller "wear" numbers. Fair enough?

Nah, that would be a waste. It would only prove we are both right.

 

[run2jeepn]

show your location for better recommendations as ambient temps are important!! they are known for rear main leakage + using a 5 or 10-30 oil helps. pick one even thrifty super tech synthetic thats almost as cheap as brand name conventionals

Southern Missouri - So we have all 4 seasons and it can change 15min at a time.

I ran Supertech Full Synthetic 5w-20 in my Charger the whole time I owned it. over 90k and never had an issue. I switched to ST early on bc I ran into a guy who had over 300k on his charger and never had any work done to. Changed his oil every 8k using ST Full Synthetic. I run it in my wifes 3.6L Dodge Journey aswell.

 

[run2jeepn]

The 3.8L doesn't care what is in it, it will drink all of it. I would use 5w30 and just keep it topped off.

See I also read that the Oil Consumption was fixed in the last couple of years and doesn't happen in the 2011s.

 

[blufeb95]

What type of rear main does Chrysler use, teflon or rubber?

 

[92saturnsl2]

I vote for thicker oil, 15w40 in hot climate, or 0/5w-40 in more temperate areas.

I’ve had leaking rear main seals before and thicker oil made a noticeable improvement; it won’t stop the leak but might buy you time.

 

[tnt_motorsports]

I just bought a 2011 Jeep Wrangler Unlimited with the 3.8L 4spd Auto. It has 160k miles on it and a very small rear main leak. Jeep runs smooth. I have non the service records. I believe I'm the 3rd owner of it. the 2nd owner only had it a 1yr and put 1000k miles on it. He changed the oil and put in 5w-20 synthetic with a Wix filter. The Jeep didn't burn any oil from what the last owner told me, but again he only pout 1000k miles in it in a year. So that doesn't tell me much. Jeep runs strong still.

My question is should I switch to 5w-30 or even 10w-30. Stay with synthetic oil?

Was thinking of switching to a slightly thicker oil and adding some Blue Devil Rear main sealer.

Not sure if it matters, but it has 37's and 4.88 gears. Has some added weight from bumpers, full size spare and hard top.

I'd use a high mileage oil to see if that helps with the leak some. As others have said it won't fix it but might buy you some time. Maybe 5W30 HM. I just switched my 2005 Jeep from Mobil 1 to Super Tech Full Synthetic HM.

Just my $0.02

 

[IndyFan]

I just bought a 2011 Jeep Wrangler Unlimited with the 3.8L 4spd Auto. It has 160k miles on it and a very small rear main leak. Jeep runs smooth. I have non the service records. I believe I'm the 3rd owner of it. the 2nd owner only had it a 1yr and put 1000k miles on it. He changed the oil and put in 5w-20 synthetic with a Wix filter. The Jeep didn't burn any oil from what the last owner told me, but again he only pout 1000k miles in it in a year. So that doesn't tell me much. Jeep runs strong still.

My question is should I switch to 5w-30 or even 10w-30. Stay with synthetic oil?

Was thinking of switching to a slightly thicker oil and adding some Blue Devil Rear main sealer.

Not sure if it matters, but it has 37's and 4.88 gears. Has some added weight from bumpers, full size spare and hard top.

If that 3.8 didn't burn any in 1k miles, then it probably is fine. Mine will burn nearly 1 quart in 1k, usually. I've run all kinds of oil weights in mine and have just settled back on 0w20. It doesn't burn any more of that weight than it did 0w40 or 10w30. Runs like new, though. I just crossed 145k on mine. If not for the lifetime warranty, I probably wouldn't bother to change the oil. It goes through enough that by 7k miles I will have added another 5.5 quarts or so, LOL!

Maybe thicker oil will help with the seal leak? I've no experience with that.

The only thing I'd suggest is not to run a Mobil 1 filter. The anti-drainback valve in them must be at the perfect angle in this engine to fail. They are known for noisy starts with that filter. Mine did that, too, the one time I tried an M1 filter. I run the Fram TG or XG 3614. No noisy starts with those.

 

[Jackson_Slugger]

...
Guys have bought Mopar Crate 3.8L's and the Oil caps say 10w-30 on many of them...

Probably because they're rebuilds using 90's or early 2000's vintage recycled engines...

I'd use a syn high mileage 5W-20 or 30 like Valvoline or Mobil 1...