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-   -   Synthetic oil on the 5.7? (http://www.jeepgarage.org/f75/synthetic-oil-on-the-5-7-a-67005.html)

zztopgun 10-22-2013 05:43 PM

Synthetic oil on the 5.7?
 
Got my 05 GC 5.7 with 90k on it and I have no idea if the previous owner used synthetic or not. I heard it can be bad to use full synthetic if it wasn't previously used. I'm just looking to get optimum engine performance and protection. I currently have a blend in it but most places don't offer blends for oil changes and I don't trust the jeep dealers. My local lube shop only offers regular or full synthetic. Any opinions and advice are greatly appreciated!

Thanks,

ZZ

lstowell 10-22-2013 06:01 PM

Re: Synthetic oil on the 5.7?
 
Quote:

Originally Posted by zztopgun (Post 915408)
Got my 05 GC 5.7 with 90k on it and I have no idea if the previous owner used synthetic or not. I heard it can be bad to use full synthetic if it wasn't previously used. I'm just looking to get optimum engine performance and protection. I currently have a blend in it but most places don't offer blends for oil changes and I don't trust the jeep dealers. My local lube shop only offers regular or full synthetic. Any opinions and advice are greatly appreciated!

Thanks,

ZZ

I would suggest using Seafoam or some other oil treatment before you cut over from synth blend to full synth. However, you could just use ordinary oil for changes and keep a bottle of good synth for topups, particularly if your dealer leaves it a bit low.

If you've been running oil good enough for the MDS, your engine should be pretty clean internally, enough you could cut over, and if you've been using a good synth blend, that would also do a good job of cleaning it out.

Still if it were my hemi, I'd Seafoam the oil soon after a change, run it a few hundred or less, then change again. If you are ultracareful, use your blend and keep an eye on it for contamination, then just cut over to full synth.

A good independent mechanic that knows the hemi's with mds should be able to tell you if you need to worry about cutting over.

Baalic 10-22-2013 07:42 PM

no need to sea foam before going to full synth, just change over and enjoy potential benefits.

Baalic 01-24-2014 02:20 AM

Re: Synthetic oil on the 5.7?
 
Sorry to revive a dead thread, but I just switched to RP for my very first oil change, so far, I actually don't see much change. Feels exactly the same as with factory oil fill, which was surprising as this is the first car/truck that I haven't noticed a difference on..... Guess the Hemi doesn't care what oil you use...... I'll keep up with the RP since I'm comfortable with it, even if it does cost a few extra bucks.... Anyone else have similar results?

*sox* 01-24-2014 03:48 AM

Re: Synthetic oil on the 5.7?
 
go with fullsyntetic, only so you have a clean engine and are much better for temperatur !

5.7 factory with MDS go with 5w20, or 0w20 Mobil 1

lstowell 01-24-2014 01:17 PM

Re: Synthetic oil on the 5.7?
 
Quote:

Originally Posted by Baalic (Post 964637)
Sorry to revive a dead thread, but I just switched to RP for my very first oil change, so far, I actually don't see much change. Feels exactly the same as with factory oil fill, which was surprising as this is the first car/truck that I haven't noticed a difference on..... Guess the Hemi doesn't care what oil you use...... I'll keep up with the RP since I'm comfortable with it, even if it does cost a few extra bucks.... Anyone else have similar results?

The hemi does care about the oil quite a bit, the stock oil is a pretty premium version in order to keep it lubed and allow the MDS to work. This may be why you don't see much difference going from a really good oil to another oil.

Jeep uses Pennzoil synth for the synth version of the Hemi. I cut mine over about 5K miles to that synth, and it hadn't used a drop from then to another synth change at 12.5K.

Note: I wouldn't seafoam or anything UNLESS your existing oil is cruddy looking--that may not have been stated well... it would only be used if the prior owner was a true jerk and didn't take care of a good engine.

Baalic 02-01-2014 12:51 PM

Re: Synthetic oil on the 5.7?
 
Quote:

Originally Posted by lstowell (Post 964847)
The hemi does care about the oil quite a bit, the stock oil is a pretty premium version in order to keep it lubed and allow the MDS to work. This may be why you don't see much difference going from a really good oil to another oil.

Jeep uses Pennzoil synth for the synth version of the Hemi. I cut mine over about 5K miles to that synth, and it hadn't used a drop from then to another synth change at 12.5K.

Note: I wouldn't seafoam or anything UNLESS your existing oil is cruddy looking--that may not have been stated well... it would only be used if the prior owner was a true jerk and didn't take care of a good engine.


Factory fill is a mineral oil not a synth oil, which is why I was surprised... I chalk it up to the fact that the detergents in the RP didn't really have anything to clean as it was the very first oil change in my 2014, and the other engines had between 30k to 70k miles when I bought them and switched to RP, which would have helped "regain" performance more then say, actually adding performance..


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