Shiano,

I run either Valvoline, Purolator or Wix.

Wix filters are a bit pricey (also sold as Napa Premium) but they are very high quality filters. A lot of great features built in to them. If you go to an autoparts store that carries wix they should have a display out with one cut apart. At work we use valvoline filters. Not as many "features" but definetly a high quality filter.  Made in USA. I have had ONE yes, ONE defective filter from valvoline and I have done HUNDREDS of oil changes with them. Purolator has a few different lines. Their premium line is close to wix, their standard line is definetly a cheaper quality. The canisters are thinner, but still, they are decent filters.

Fram is junk. I believe mopar filters are made by WIX, and stay away from off brand filters, especially imports from china.

As for torque and HP increases, thats a load of crap. It will not INCREASE horsepower, it will only recapture some of it lost to friction. These oils make these claims because they can reduce FRICTION  better (not necessarily wear). As for Royal Purple, HP "gains" are only like 2-3%.

Jiim

I was talking about HP at the wheels, not the engine. You knew what i meant. lol.

Wix is good, definitely. However, several independant studies have been done that found the Purolator Pure One and Wix were so close to each other on quality that to say one was better than the other based on performance was redundant. Therefore, you move on to the next factor: Cost. The Pure Ones have always costed less around here where i live, therefore, thats what i've been using since i learned the truth about the two.

And stay away from the Mopar filters. They are a mix of Fram, Wix, and Purolators. Whoever is selling the cheapest at the time, is the one that slaps the mopar name on the filter. The filters aren't built to Mopar specs b/c Mopar has no required specs for the filters. They rely on the filter companies to do that.

With the A604, it keeps alot of the hp of the V6 and the I4 from reaching the wheels, therefore, it's alot more noticeable when any of it is restored.

lol. yeah, when i worked at Advance Auto and O'Reilly Auto Parts, commercial accounts would get some sweet deals. Of course, the employees got the best deals. 10% above cost.

But if you run the synthetic, just like a fuel system cleaner [and i mean Lucas, not that watered down STP, Valvoline, Chevron, etc. crap] you have to let it work for a little before you notice the full results. After I changed to synthetic, my fuel mileage jumped from 24 to 27.5. So if you dyno it with the synthetic, wait until 2 changes later.

of course, a Lincoln Continental ended my cars life before i could do the second oil change [his fault]. But it was still worth it to me.

I'm the second owner of my car and I got it at 109k... Previous owner used Penzoil.. Started to use Castrol Syntec Blend w/ a Purolater Pure One Filter and noticed a nice increase.. About 100 miles b4 I had to change it I put in Seafoam cuz I heard good things about it... I was supposed to leave it in there for 100 miles but it was in there for about 50 miles... It was pitch black.... And sludge like... Why? Cuz Penzoil is parrafin based aka wax.... Let me tell you, my car didn't even have this much get up and go w/ a tune up.... So it proves Penzoil gums up your engine... I'm gonna use another can at the end of this oil change for the full 100 miles and reap the benefits from that... Just my 2 cents

I know I should've posted before now...I did the oil change two weeks ago @108,000 with Valvoline V-Tech and a Purolator PureOne.  I also replaced the air filter with the K&N stock replacement (not the cold-air conversion...I'm not THAT wealthy). 
The first thing I noticed was, as stated, the lack of ANY oil pressure at idle.  This started to bug me.  I went over to the local Chrysler Dealer, who first started to berate me for spending $50 an oil change on synthetic ("but I got a free carwash"), however when I mentioned that before, as well as now, I have no oil leaks at all, he changed his tune.  I guess several people in the last 6 months have been dragging their cars in with no oil in the crankcase, due to trying to run synthetic on cars with minor but evident oil leaks.  The lead mechanic then called the dealership's Mitsubishi partner and sent me over there.
I went there and spoke with a gent about the whole mess.  He said that if I'm running synthetic, don't worry overly much about the pressure (still do).  He also said that even though they commented on being able to run Synthetic for 5-7k, change it every 3500.  Same reason as mentioned above, the particulates it picks up, coupled with it's warm constant viscosity allows for gunk still hanging around.  Oh well.  It keeps me from throwing Marvel Mystery Oil in it.

The plugs I picked up were the Denso Iridiums, but I'm paying someone to put those in...the back three look like a Migraine waiting to happen.

The funny contrast here is that in my '99 Jeep Cherokee, the mechanics, dealers, experts, old-time-owners and television pro's say don't even consider using Synthetics in the 4.0L with high mileage.  Apparently, they recommend going to higher viscosities at higher mileage...

who knew?

ngk copper v-power