its not going to hurt anything, but if yo switch to synthetic you may develop some leaks as the synthetic oil is thinner than regular dino oil. so basically if you had something which was close to leaking w/ dino oil, it will leak with synthetic, wont hurt anything, but i wouldnt do it JMHO

 

Not thinner just better detergents which will open any leaks. Mine started leaking a little after switching to synthetic but w/e that's just the name of the game.

 

Correct.

It's the same viscosity it just flows better with better detergents. When it's cold regular oil can get thicker where-is the synthetic stays liquid like. This sitting on any small weeping gasket "can" leak more. The biggest thing here is the Fully Synthetic has better detergents which clean better. Any crap or weak spots then get cleaned out causing the leak. Think about it like removing mineral deposits on a small water leak. With the deposits it seals but remove them and you have a drip. Fully Synthetic is regular oil base but further processed then mixed with detergents, additives, and modifiers.

Now if you have any deposits between the compression rings or oil ring on the pistons then the better detergents can clean out this area thus causing burning oil.

Now considering that you have replaced the motor and you only have 25k on it shouldn't have to worry about it (if I read your 1st post correctly). Personally I would take it to your Quaker State Quick Lube over Jiffy Lube ANY DAY! I hate Jiffy Lube!

If you run Fully Synthetic 10W-30 then you need to change your oil about every 5000 miles where-is regular conventional needs every 3000 miles thus saving you money. As with anything, if you wheel or off road then your oil life goes down because of shearing of the lubricant additives. The oil base it's self is reusable and it is stripped from the additives and polymers then mixed in with new to be recycled at the manufacture. I have had cars running 7500 mile intervals and my truck at 5000 mile intervals because of what I do with my truck. My personal tests as well as Manufacture inside knowledge (Mobil 1 test results) by my father-in-law (tester and Chemical Engineer) mileage recommendations. If you follow these rules then you can save money and ware because it might cost more to do the changes when you do them BUT it adds up to save you money both in the long run and during the the amount of changes needed. But each to their own.


By using Fully Synthetic it will help you clean out the motor IF you have some kind of build up in it. But if you are tapping and had just the bearings replaced then it could be the wrist bearings. I guess the main question here is.....What exactly did you do to the motor?

Here is some other info I did over in the Durango 2nd generation: Oil Questions?

 

I guess that wasn't clear. I have the same engine in the car, with 175 grand on it. It had 155 grand on it when it 'sludged up' according to the original mechanic who did work on it. He dropped the pan, cleaned the sludge, and replaced rod and main bearings. It still had a tapping in the top end, but I didn't have money for him to do any more work.


Aha, this is a new component I hadn't heard about. It makes sense that it might be the wrist bearings. What exactly did I do? I do not know. Here's a chronology of events as I know them.

April 2009 at 155k - engine sludged. Level was good, but no pressure. They dropped the pan, cleaned it out (no, I did NOT see it) and replaced rod and main bearings (yes, I DID see them, and they were torn up.)

Late October 2010 at about 173K - two cam followers jumped off and were replaced along with the valve adjusters.

November 2010, a day after the car was delivered from the above repair (it sat for awhile), at about 173K - Another cam follower jumped, and all lifters were replaced at this point.

November 24, the coolant maxes and the oil pressure bottoms out. Try and baby it home, but end up towing it.

November 25, wrench on my Diesel Passat and mope.

November 26, eat turkey and mope. I found a 5.9 out of an insurance wreck for $300 on Craigslist. Debate the advisablility of putting that in.

November 28, spin off the old oil filter, put a new one in, put a quart of 5W30 and take it to JL for an OC. Pressure stays at the low end of 'safe' (let's assume 20PSI.) During some short errands, pressure returns to mid normal. WTF??

November 29, start it a couple times. Pressure normal each time. Take it on short trips. Pressure rock steady normal.

December 1, another short trip with normal pressure.

Today, December 2, took it to work - a 60 mile commute one way. Normal pressure - meaning that after things heated up, it came down but still above 20PSI and no fluctuations or dropouts.

I'd say I had a blockage somewhere that cleared. I would also say that my wrist bearings in at least one cylinder are shot. No way of telling without a scope where the issue is. At this point, I'll probably just run it till it drops, and put my pennies and nickels and dollars towards a replacement engine.

 

You should have more PSI than 20 with new bearings bringing the tolerances closer. The fact that you only have 20 psi means that the pump is on its way out to me.


If I were you (and you never heard me say this) get a bottle of SeaFoam fro your favorite auto parts store and pour half into the crank case. Then start it up. Do this on a warm engine by the way. Then with the hood open and the air hat removed gently pull the throttle plate open tell you get about 2000/2500 rpm's then gently drizzle (I mean GENTLY) some down the throttle body. You will hear the engine bog a little and drizzle down more when the rpm's get to normal. Do this until you have at least dropped 1/4 bottle down the Throttle Body.

Now keep in mind that your truck is going to smoke like MAD! This is the crap blowing out. Next drain the oil and change the filter with throw away oil and cheap filter. Pour the rest in the fuel tank (hopefully you have a 1/4 tank). Now let the new oil stay in for about 100 miles then change it again.

This will clean out the crank case and combustion cylinders. The next step would be addressing the oil pressure if this doesn't fix it.

 

I usually run the seafoam in the crank case for 100-150 miles, then change it. Let it cycle throughout the oil passages. I highly doubt it will fix your oil pressure issue.

Could their possible be something wrong with the gauge cluster? I mean did it sound like it lost oil pressure? Like you would hear the lifters and valvetrain ticking like mad.

 

Yeah, I guess so.

A reminder; the low end of the safe range; right above where the 'check gauges' warning lights - that's what I'm calling 20 PSI. I do not know if that's the actual pressure or not yet, haven't gotten a round tuit to get a mechanical gauge on.

Anyway,after two days of commuting, I have baseline behavior:

Engine starts out with oil pressure normal when cold.
After it gets to operating temp, it falls slowly to the low end of safe. "20 PSI."
It will stay here, quite constantly, but after about 45 minutes or so it MAY also drop to zero oil pressure and the warning light will come on. When this happens, I shut the engine off and wait 5 minutes. After 5 minutes, I can turn it on, and it again goes to the low end of safe. "20 PSI."

I've done Seafoam in it, and I'm now using 3 oz. of Auto-Rx during each oil change.

And I'm also looking for a 4.7L that I can get cheap so that I can replace this motor when the time comes. I'd rather do it now when it's running than wait till I'm stranded.

 

Bjamik, it's not a good idea to use something like sea foam in the crankcase for longer than prescribed. Stuff like sea foam is great at cleaning but not lubing.

Rah, try replacing the oil pump, it will be far cheaper than a new engine. Once the problem has been resolved you can send me the difference. Cash, check, or a money order are all acceptable forms of payment for me.

 

yup +1

 

sludge is bs drive the d through his shop and say the brakes didnt work cuz they had sludge in the lines stupid b****rd should have just said he didnt know