I gotta agree with Cheech. When I bought my Grand Cherokee, it always got changed by the dealer for the previous owner, so you know it was conventional. I switched to RP and at 6k it was black, much blacker than the conventional that came out. Cool thing is, the next change at 6k it came out clean, very clean. Leading me to believe that the first dose of RP did a damn good job of getting the sludge and gunk out...

I went from always using Mobil 1 to RP in the truck, it's not been changed yet, but I'm anxious to see if going from one synthetic to another yields similar results...

 

Well considering what happened with your Jeep I might change my oil early to get all that crap outta there.

 

I use RP and I never did any flush. RP is the most expensive of them all though.

 

Yeah, that's why I said in my earlier post to probably change it at 3k the first time...

 

That and considering the previous owner didn't exactly change it regularly make me more likely to change it earlier. The 2 changes I have done both only took 4 1/2 qts to fill it (it's a 3.7) and it is supposed to be 5, so I'm kinda worried there might be some sludge in there.

 

I say throw a quart of Marvel mystery oil in there withe the next oil change and run that for 2kmi and then switch to synthetic.

Make sure you have the right oil filter. They make shallow and tall filters for most makes models. maybe that could be a reason for the 4.5qts? or your not getting all the oil out when you drain.

 

When I changed it last week I drove it around like 15 mins to let it heat up and then pulled in the garage on a level floor and drained it for 10 mins until it was just dripping every couple seconds. The filters I have seen are all the same size, from FRAM that the previous owner had on there, to NAPA to the pureone on there now. I have talked to the other v6 guys and they said most of their's take 5 on a change or at the least 4 3/4 to hit the mark on the dipstick. I'll see how it looks when I get enough miles to drain this one.

 

you do not need to flush, the oil will just get dirtier faster because synthetic cleans out sludge