15W40 Heaven!
#81
JK Freak
Actually It has gotten better just by changing the way I drive it. Instead of lugging it around trying to save gas, I just drive it as any normal car or truck and let the engine rev.
I just got an article in an off road magazine that said the same thing. Drive the 3.8 like you don't like it and it will do better. Seems to be working.
I'll try that seafoam treatment at the next oil change too.
I just got an article in an off road magazine that said the same thing. Drive the 3.8 like you don't like it and it will do better. Seems to be working.
I'll try that seafoam treatment at the next oil change too.
#82
JK Enthusiast
Join Date: Jul 2012
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Originally Posted by BacasJK
Using 0w-40 Mobil 1 and no oil consumption.
Mopars love thicker oil. period.
Martin
Mine- 2011 blk. Rubi.
Hers- 2011 Slvr. Rubi.
Mopars love thicker oil. period.
Martin
Mine- 2011 blk. Rubi.
Hers- 2011 Slvr. Rubi.
#83
I noticed a significent decrease in engine noise when switching to 5w-30. I'v sent off a sample of my used oil since switching, and every wear metal is within universal averages except for copper, which seems to be excessivly high in every UOA (used oil analysis) I have seen for the Wrangler 3.8, including those who use 5w-20. I imagine there are lots of people on this forum who would be very interested in seeing a UOA of your oil when you drain it. That will give us a hard answer to the question of using thicker oil. I usually go through Blackstone labs and they charge $25.
Last edited by 13rubi; 09-04-2012 at 02:04 PM.
#84
JK Enthusiast
This makes sense. Puttting a more viscous liquid into the same space ( oil clearance of main bearings ) will increace oil pressure which in turn will prematurley wear out bearings not designed to work at that pressure. This is called bearing errosion. I would also expect to see and increase in tin and babbit in your oil too. Did you do and control pre 5/30 samples to compare? A thicke oil can also cause more wear on cold starts. As a dealer tech for over 17 years I am a big believer in using the manufactuers recamended oil wts. I have seen too many damaged engines with denied waranty claims to think othe wise IMHO.
#86
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That's interesting, seems there are mixed reviews.
Sounds like I won't be able to do this "trick," being that I'm in the MidWest. Summers get 100+, however, Winters fall very cold.
Mine's a JK '07, Manual 6speed, 3.8L. I'll keep an eye on this for the future, though.
Just changed my oil this weekend, used 5W20 royal purple, and then used a pint of the seafoam fuel cleaner. Still waiting to drain the tank and see any differences with the injection.
Sounds like I won't be able to do this "trick," being that I'm in the MidWest. Summers get 100+, however, Winters fall very cold.
Mine's a JK '07, Manual 6speed, 3.8L. I'll keep an eye on this for the future, though.
Just changed my oil this weekend, used 5W20 royal purple, and then used a pint of the seafoam fuel cleaner. Still waiting to drain the tank and see any differences with the injection.
#87
JK Junkie
Here's my 2 cents... Oil viscosity changes quite a bit with temperature. Engines have to be designed to handle variations in oil temperature, which is going to vary with RPM, power, ambient temp, etc.
One can use a viscosity calculator such as the one at bobistheoilguy, along with the viscosity specs for a 5w-20 oil at 100 and 40 Deg C, then figure how much temperature reduction from 100 C would make the 5w-20 oil equal the 100 C viscosity of another oil.
Just compared a 5w-20 with a 5w-40, there's about 18 deg difference in temperature (near 100 deg C) for equal viscosity in cSt. So 5w-40 is like running 5w-20 at 18 deg cooler temperature. And since they are both 5w for the winter rating, they have roughly equivalent viscosity for cold weather startup viscosity.
Bottom line, I'm not concerned about any bad side affects, other than a slight MPG loss, from substituting 5w-40 for a 5w-20. I've used 5w-20 and 30, and am running 5w-40 now. This engine doesn't use oil even with 5w-20, but there is a slight audible difference -- more like a Mercedes with 5w-40. Driving in Death Valley in summer, and the Oregon mountains in winter, 5w-40 synthetic makes sense for me. At some cold start temperature, a 15w-X becomes a limiting factor.
One can use a viscosity calculator such as the one at bobistheoilguy, along with the viscosity specs for a 5w-20 oil at 100 and 40 Deg C, then figure how much temperature reduction from 100 C would make the 5w-20 oil equal the 100 C viscosity of another oil.
Just compared a 5w-20 with a 5w-40, there's about 18 deg difference in temperature (near 100 deg C) for equal viscosity in cSt. So 5w-40 is like running 5w-20 at 18 deg cooler temperature. And since they are both 5w for the winter rating, they have roughly equivalent viscosity for cold weather startup viscosity.
Bottom line, I'm not concerned about any bad side affects, other than a slight MPG loss, from substituting 5w-40 for a 5w-20. I've used 5w-20 and 30, and am running 5w-40 now. This engine doesn't use oil even with 5w-20, but there is a slight audible difference -- more like a Mercedes with 5w-40. Driving in Death Valley in summer, and the Oregon mountains in winter, 5w-40 synthetic makes sense for me. At some cold start temperature, a 15w-X becomes a limiting factor.
Last edited by Mr.T; 09-05-2012 at 08:35 PM.
#88
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This makes sense. Puttting a more viscous liquid into the same space ( oil clearance of main bearings ) will increace oil pressure which in turn will prematurley wear out bearings not designed to work at that pressure. This is called bearing errosion. I would also expect to see and increase in tin and babbit in your oil too. Did you do and control pre 5/30 samples to compare? A thicke oil can also cause more wear on cold starts. As a dealer tech for over 17 years I am a big believer in using the manufactuers recamended oil wts. I have seen too many damaged engines with denied waranty claims to think othe wise IMHO.
In this picture, the current (leftmost) numbers are from Rotella 5w-40 Diesel oil. The next two are Royal Purple 5w-30, and the last is Penzzoil Platinum 5w-30
#89
#90
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On a side note, Rotella 5w-40 did give me occasional start up noise in the winter, but regardless, the oil sample was still better. I'v got 5w-30 in my engine now as I wanted to see the results of this last sample before sticking to 5w-40, and I'll probably sample it as another control sample. Next time I'm giving Mobile 1 5w-40 a shot to try and avoid start up noise, as it tends to have a bit better cold flow.
Man... I'v spent too much time on bobistheoilguy forums.