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Synthetic vs. Conventional Oil, which to use 5.7L

32K views 26 replies 23 participants last post by  GTREVINOWK2 
#1 ·
Normally this isn't a question I would ask as I have used Synthetic Oil for many years (Mobil 1 and Red Line) and even use it in my garden tractor. However my Indy shop will be changing the oil this week and is pushing me toward Conventional (mineral) Oil. The reason given was since the factory uses this for break-in the molecules have already bonded to the cylinder walls and rings and therefore I would be wasting my money in using a Synthetic.

I know there are benefits to using a Synthetic including a lower viscosity during the cold weather which helps in reducing wear of critical engine components.

The Indy shop is very good has been maintaining my past vehicles. They specialize in German branded vehicles but work on other makes as well. Their interest is just to give me honest advice and perhaps save some $$$.

Most likely I will go with Mobil 1 but I wanted to ask fellow forum members if they have gone through a similar thought process. As a side note, have you stayed with the factory recommended 5W-20? I used Mobil 1 5W-30 in my wife's car and tractor. It would be convenient to stay with one viscosity type but it is not essential.

Last question, as far as the oil filter, Mopar or other brand?

Thanks in advance.




Regards,
NHman
 
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#2 ·
that's a myth and really only applies to old engines which have been run in conventional for a long time and even then, its questionable.

synthetics usually have higher additives and detergent, and can "degunk" and open up seals, but it really is not the case with modern seals.
 
#4 ·
If you feel more comfortable with synthetic, that's what you should use. Some change to it at the first change, some wait until they have 10K miles on the vehicle. Do a search, you'll find many discussions on the topic.
The SAE 5W-20 viscosity grade is required for the 5.7L Hemi, it has to do the the MDS. Using a different viscosity will likely get you a check engine light. Although some have said they've used 0W-20 Mobil 1 with success.
The Mopar filter is adequate, but the Motorcraft FL-820S will also fit and is recommended by many here (including myself).
 
#6 ·
Stick with 5w-20 for the 5.7 with MDS, a buddy accidentally used 5w-30 and had trouble until he switched back. Filters seem to be a personal preference, I have liked purolator pure one filters, just my 2 cents worth on that. With modern engines and seals and modern chemistry there is no harm going back and forth with synthetic or mineral oil, but if you live in a colder climate synthetic is probably better.
 
#8 ·
The only tangible advantage I've noticed over the years with Synthetic is a smoother start in the winter, especially below -10 C. My Jeeps are parked outside and although the block heater (standard in Canada) helps the most in freezing weather, when I do forget to plug it in, the Synthetic comes to the rescue.
 
#10 · (Edited)
Man, for as many threads that exist over this subject, the lack of knowledge on this subject is amazing! Do people really read anything further than the first few sentences in those posts?
Both Dino oil and synthetic perform their responsibilities to provide lubrication and cooling for engines. There isn't any debate or argument over this. But if you still have to ask which one to use, then I'd suggest you move out from the rock you have to be living under to not know and understand the clear advantages of synthetic oils. Dino oil's have to use modifiers and other additives to be able to keep the molecular strings together longer in order to suspend particles and lubricate. That's why dino oil only lasts for 3,500 miles.
Sythetics don't need all those additional additives, and provides even better lubircation and cooling which allows you to drive longer between oil changes, which saves you time and money.

When synthetic oils first came out, the problem wasn't the oil, it was the gaskets that were being used. But for the last 10 years now, that has been addressed and you can use either synthetics or dinos and it won't hurt your engine or oil lines anymore. You can even go back and fourth between the two if you want now. Also oil pumps and sending units have been designed to deal with the "thinner" viscosities now to keep the correct oil pressure.
 
#11 ·
My personal preference is the new Pennzoil Ultra 5w-20 with the mopar filter
I'll expand a little since I re-read your original post. The comment about the molecules bonding to the metal was so far out in left field that I ignored it until I noticed it was an Indy shop that specializes in German vehicles. I have had run ins over the years with some of these Germain vehicle Indy shops coming up with all kinds of urban legends regarding oil, filters, gas, you name it. About the only place worse are Harley mechanics who still cling to the urban legend that synthetic oil is "too slippery"....... LOL

Modern synthetics are simply better at doing what a motor oil is supposed to do than anything that has come before. There is no argument to this previous statement that can stand the test of science, none. While there may be some older engines that need more zinc and other minerals than is currently allowed in modern motors that argument doesn't counter my statement. There's a corollary that is true as well, modern non-synthetic are also better at doing what they are designed for than their predecessors. With that being said, NEITHER oil will cause harm so what you use really comes down to what YOU think is the best thing for your motor.

BTW, the problem with seals about 20 years ago WAS partly due to the type of synthetics being produced. Some of the early Group V or Non-PAO based synthetics caused seal degradation do to the corrosive effects of diesters, polyolesters, alklylated napthlenes, alkyklated benzenes, etc. Currently, all main stream "100% synthetic" oils are made from a combination of Group III and Group IV Polyalphaolefin (PAO) base stock that do not degrade plastics AND are molecular compatible with mineral oil so they can be mixed without significant harmful effects.
 
#13 ·
I have run Amsoil 0w-20 in both my Hemi's; one has 14,0000 and the other 17,000 miles. I just changed oil in both again, we are moving to MA and didn't want to mess with it later. Runs great and the extended drain intervals are nice.
 
#14 · (Edited)
I run 5W-20 Castrol Edge (synthetic) and Amsoil EA048 oil filters on my 5.7 with MDS. Change em' every 5 months or 5500 miles. Issue here is 75 dollar oil changes but, for a 40K+ vehicle....cheap insurance in my book....


FYI....further research indicates that Jeep can (and will most likely) void your warranty if you do not follow the owners manual: You must change the oil every 6 months or 8K miles...period....pg 540

NOTE:​
•​
The oil change indicator message will not monitor the
time since the last oil change. Change your vehicles oil
if it has been 6 months since your last oil change even
if the oil change indicator message is NOT illuminated.

•​
Change your engine oil more often if you drive your
vehicle off-road for an extended period of time.

•​
Under no circumstances should oil change intervals
exceed 8,000 miles (13,000 km) or 6 months, whichever
comes first.

 
#23 ·
My 2003 Saab 9-3T Arc has 118,000 miles on it and still runs great after having its Mobil 1 synthetic oil changed every 15,000 miles. Yes, it has a high revving four cylinder turbocharged engine and has gone 15,000 miles on every oil change. I can't recommend synthetic oil enough.
 
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