Castrol GTX HM 10w30 +STP/3,300mi/99 Durango 5.2

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Ok, I've got a 99 Durango with the 5.2L (318) V8 and selectable 2wd/awd/4wd. It's got 168,000 miles on it right now. My parents bought it new and I've had it for the past 6 years and ~60k miles. My dad always changed the oil every 3,000-4,000 miles with Wolf's Head 10w30 and a bottle of STP. Since I've had it I've been using Castrol GTX High Mileage part synthetic 10w30 and a bottle of STP every 3,000 - 3,500 miles. I use Purolator or Mopar (made by Purolator) filters.

The motor doesn't have any leaks, smoke, etc... and still runs very strong. It does burn about 1 qt every 2,000 or so miles. I usually don't drive very hard, usually not going over 2,000 - 2,500 rpm, but every once it a while such as getting onto the highway I let it wind out. I'd say I have pretty much a 50/50 split of highway and in town driving other than when I'm travelling between PA and SC (getting 17-18mpg surprisingly).

The climate really varies because I spend parts of the year in Pittsburgh and the rest in SC. My air filter is a k&n oiled reusable one in the stock airbox.

Anyway, here's the oil report.

orowh3.jpg



I'm no expert, but the way I read this it seems like there isn't much wear material in the oil. So any thoughts on the report and how well the oil is performing?
 
STP will increase the viscosity of your oil, so I'm not surprised it's reading in the 40-grade range. The wear looks great, and it seems like your K&N isn't letting too much dirt through. Did you warm the car up fully before getting the sample? For best results (and to see if your engine really is dumping too much gas into the oil), make sure to get the oil up to operating temperature by taking it on a long trip beforehand. Welcome to BITOG!
 
Instead of the STP,you should run an oci of GTX 10W40HM or 20W50HM and see what happens,but,if the STP has zinc/moly (or some other anti-wear stuff like I "think" I read here someplace?) it might be good for your high mileage engine. Your uoa looks great!
 
I had drove to Wal-Mart and back getting the oil before I changed it and got the same if I'm remembering right, do about a 12 mile round trip. The coolant was up to temp, but I'm suspecting the oil might not have completely been. Supposedly it takes a good bit of time for the oil to fully warm up in these engines. Most of the trips I make any more than 15 miles or so, so I would suspect that explains the gas content in the oil.


The reason I've been using the STP is the added zinc. Would it be worth not having that anymore?
 
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The 10W-30 and the can of STP did very well for this engine.

A viscosity of 11.36 is a nice healthy viscosity at the upper end of the 10W-30 range.

I'd keep doing the same if it was me.
thumbsup2.gif
 
Greetings:

Just a few thoughts on your Durango:

I would skip the STP from now on - it really isn't needed with today's oils. Your engine seems to be wearing well and should do fine without it. Oil has come light years since additives like STP were developed. Any good 5W30/10W30 today should serve you well by itself.


The 5.2 and 5.9 Magnum engines commonly blow the lower intake plenum gasket and the lower cover also warps. When this happens, the engine sucks oil into the intake and burns it up. It can also cause spark knock. Perhaps your lower intake plenum cover is warped and/or the gasket is blown. This might account for the oil that you are burning. Here is a video that should be helpful:



I believe you can open the throttle plates and look into the intake to see if any oil is visible in there. If there is oil in there, you can bet the plenum is blown.

Some additional notes:

You probably have the 44RE transmission. If you haven't done it already, I would change the filter, adjust the bands and replace the fluid with ATF+4 fluid. A good stacked plate transmission cooler installed in series with the radiator cooler in the return line would be a good edition for longevity. If your Dodge has a check valve in the return line, it would be a good idea to remove it because these sometimes fail and cook the transmission.

Best wishes for many more miles on your 318.

Andrew S.
 
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My dad said the dealer changed the plenum gasket years ago under warranty, so I don't think that's an issue. There's not oil or anything in the intake either. There's some oily residue coming from the crankcase breather into the air hat though. I just installed a catch can to see if it's a significant amount. I do plan on eventually getting one of the Mopar performance intakes that do away with the plenum pan though.

I do have the 44re transmission. I changed the filter and fluid a couple years back, didn't adjust the bands though. Adjusting them and adding a new transmission fluid cooler are on my list of things to do.
 
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Originally Posted By: that_guy318
I had drove to Wal-Mart and back getting the oil before I changed it and got the same if I'm remembering right, do about a 12 mile round trip. The coolant was up to temp, but I'm suspecting the oil might not have completely been. Supposedly it takes a good bit of time for the oil to fully warm up in these engines. Most of the trips I make any more than 15 miles or so, so I would suspect that explains the gas content in the oil.


The reason I've been using the STP is the added zinc. Would it be worth not having that anymore?


Keep doing what you're doing, if you like using it. The engine is wearing great.
 
Originally Posted By: ThirdeYe
Originally Posted By: that_guy318
I had drove to Wal-Mart and back getting the oil before I changed it and got the same if I'm remembering right, do about a 12 mile round trip. The coolant was up to temp, but I'm suspecting the oil might not have completely been. Supposedly it takes a good bit of time for the oil to fully warm up in these engines. Most of the trips I make any more than 15 miles or so, so I would suspect that explains the gas content in the oil.


The reason I've been using the STP is the added zinc. Would it be worth not having that anymore?


Keep doing what you're doing, if you like using it. The engine is wearing great.


^^This. Your uoa looks great! I'd just keep on keeping on.
 
Was the STP additive just the standard blue bottle or was it the high mileage version?
 
Thanks for posting! I have long wondered what a UOA with STP in the crank would look like, even considered doing one myself but got distracted with other experiments.
 
Yeah, it seems like the stp is working. I'm kind of surprised that there wasn't more zinc showing up on the report though. I'm going to keep using it though, it's worked for years, so why change it.

My grandpap said that he took the heads off of his 83 Pontiac with the 305 and 130k miles (the distributor got water in it, made it backfire, and screwed up something that I forgot the specifics of), and the original honing marks were still there, there was no lip at the top at all and the positions came right out. His rebuilder measured it and there was less than a thousandth of an inch of wear only at the bottom of the cylinder. He always ran stp in it since he bought it with less than 10k miles.
 
Blue bottle STP does have zinc, but less than the motor oil you are adding it to. It is primarily an oil thickener. I still have a soft spot for it though. No oil change was complete without a can of STP when I was a teen. Have used it in the Jeep fairly recently and it did seem to like it, the Jeep does favor thicker oils though.

Great UOA I wouldn't change a thing it's obviously working for you.
 
I think my engine likes the thicker oil too. I have right under 40lbs of pressure at idle and right under 60 or so at cruising speed.
 
Originally Posted By: that_guy318
Yeah, it seems like the stp is working. I'm kind of surprised that there wasn't more zinc showing up on the report though. I'm going to keep using it though, it's worked for years, so why change it.

Somewhere in the VOA section, I did the calculations to show that regular STP will actually dilute the zinc content of most motor oils. It's worse than useless as a ZDDP additive.
 
Originally Posted By: Garak
Originally Posted By: that_guy318
Yeah, it seems like the stp is working. I'm kind of surprised that there wasn't more zinc showing up on the report though. I'm going to keep using it though, it's worked for years, so why change it.

Somewhere in the VOA section, I did the calculations to show that regular STP will actually dilute the zinc content of most motor oils. It's worse than useless as a ZDDP additive.


It looks like it increased the zinc content of my oil though. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1414695
 
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