What are the pros and cons of using a synthetic 10W30 versus conventional motor oil in my 2005 4.0L? Thanks!
Which oil is best?
- Thread starter HeffTJ
- Start date
I use regular 10w30 or 10w40 dino oil. I also change mine every 4k miles.
not really sure about pros or cons.
not really sure about pros or cons.
Thanks. I'm also a stickler for changing every 3,500 miles. It's cheep insurance or maybe I was just raised to think so, but I do!
I would avoid synthetic. I tried it in my 4.0 and developed a rear main seal leak.
Next oil change, I went back to conventional oil and the leak stopped.
I didn’t know about the synthetic problem until I read about it in online forums, and proved it to myself in my Jeep.
It seems synthetic oil is “thinner” than conventional oil, and has the tendency to seep past seals.
I went with high mileage conventional BTW, and haven’t had any issues since.
Next oil change, I went back to conventional oil and the leak stopped.
I didn’t know about the synthetic problem until I read about it in online forums, and proved it to myself in my Jeep.
It seems synthetic oil is “thinner” than conventional oil, and has the tendency to seep past seals.
I went with high mileage conventional BTW, and haven’t had any issues since.
TJRick
TJ Enthusiast
The "every 3000 miles" rule was invented by quick oil change companies in order to make more money for themselves.
Unless your oil is dirty or it takes you six months to accumulate that mileage, you are wasting your money.
According to the Owner's Manual, you should change your oil every 6 months or 7500 miles under normal driving conditions.
TJ2
TJ Expert
These 4.0s aren’t very picky when it comes to oil. I have always run just regular 10W30 Dino oil and mine seems perfectly happy. I do always use a Mopar filter though.
While your statement is true, for normal driving conditions. Most of the USA, especially the East coast is considered severe duty driving. This warrants more frequent oil changes, every 5k.
TJRick
TJ Enthusiast
I'd say I'm in the "severe duty" area.... I typically change oil to how it looks more than milage. Never more than 4-5K otherwise.
TJ2
TJ Expert
Severe duty is considered any condition where the vehicle is used for towing, mountain/hilly areas and high traffic areas where the vehicle is sitting in stop/go traffic or idling for extended period or traveling at higher rates of speed.
Being a GM technician, I can tell you draining the oil out of a 4k mile vs 7500 mile engine is a difference of night and day.
I can also tell you that the engines that see a more frequent service interval are the ones that last longer.
Most of the engines I tear down for internal problems are due to extended service intervals.
So to me changing the oil every 3-4k miles is not a waste of time, it's preventative maintainence that will extend the life of your vehicle.
GM vehicles have a oil life monitor system and yes you could get 7500-10000 miles before the oil life hits 0%, but we still recommend every 5k when using GM Dexos synthetic oil.
Several of us (myself included) have tried synthetic only to find that the hydraulic lifters in the 4.0 start rattling and ticking like crazy. I couldn’t believe how loud it was. After about 50 miles I immediately went back to conventional 10w-30 and the noise went away.
Yep. I was an ASE certified master tech for 15 years - long time ago now - but the basics don't change. I certainly won't dispute the comments made by 4.0 owners who started to notice lifter noise, but I am willing to bet that had more to do with the weight of oil than the fact that is was synthetic. Regardless, changing oil and filter regularly is key to engine life.
Interesting..... I've used the Pennzoil Platinum Synthetic high milage formula for a couple changes now and haven't noticed any lifter noise. I'll have to pay closer attention maybe....