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I did have similar... 2007 Grand Caravan, oil pressure light would flicker when cold, at idle, also some knocking sounds from the engine (which I had thought were "normal"...) I replaced the lifters and the camshaft, oil pump, timing chain and things were "nice and quiet", until I found out (unfortunately a little too late) that the REAL reason was the lower end bearings - rod bearings and main bearings. (In the middle of a cross-country trip, one of the rod bearings went out completely, rod knocking and all...)
I tried to salvage it with new bearings (at the motel we stopped at) but by then the crankshaft was already damaged and after a few of miles of smooth running, the knocking came back and I ended up getting rid of the van and getting a different vehicle to continue the trip with. But in changing the rod bearings, the old ones turned out to be QUITE worn, the REAL reason for the low oil pressure.
I still got my money's worth out of the van (was at about 333,000 miles) but I was hoping to get it to 600, which I ended up changing my mind on at that point ;)
 

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Post #20. 5W-30 and 10W-30 sound good, no 5W-20 weakling. :) Higher output engines tend to use heavier oil for good reason.
Oil that’s too thin can also lead to insufficient oil pressure to properly operate your vehicle’s variable valve timing system, if equipped. Low pressure may also result in lifters not staying in contact with cams, causing noise and increased wear
 

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Post #20. 5W-30 and 10W-30 sound good, no 5W-20 weakling. :) Higher output engines tend to use heavier oil for good reason.
Well, oil viscosity should be determined by temperature range, bearing clearances, and/or oil pressure.

So as your engine wears out, in theory you should be increasing the oil viscosity to compensate for the increased clearance and reduced pressure.
 

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Well, oil viscosity should be determined by temperature range, bearing clearances, and/or oil pressure.

So as your engine wears out, in theory you should be increasing the oil viscosity to compensate for the increased clearance and reduced pressure.
I agree.
The move toward lighter motor oil is not driven by durability though. Driven by tolerances (of what or all components) is questionable as well. In fact, wear protection becomes a challenge for the additive package as viscosities go lower.
Although it will help improve fuel efficiency throughout the entire oil drain interval, it opens the door for increased wear and tear on critical engine parts. This makes the development of new additives suitable for ultra-thin oils in high power density engines that much more critical.
As for clearances/tolerances being a driving factor, all motor oil is very viscous (high viscosity, thinking molasses) during cold weather startup and engines tend to run cooler during cold weather. Same engines and "operating" oil specs are used north and south. Heat seems to be more of an issue than cold. Consider rocker arm needle bearing failure in the 3.6L engine using 5W-20 oil. Oil film too thin?, needle bearings aren't rocket science Toyota was known for higher tolerance engines for years and still used 5W-30 motor oil. Engines in North America, Ford for example, requiring 5W-20 were requiring 5W-30 in Europe. Go figure, but nothing to do with tolerances.
Maybe hype and marketing will be replaced by truth some day. :)

Tolerances or clearances aren't even mentioned in this article.
 

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Discussion Starter · #26 ·
Thanks for the specs and procedures.

I asked my mechanic to measure the oil pressure and listen to the engine as a second set of ears. These were his readings with the engine at idle (700 rpm):
Oil cold: 15 - 20 psi
Oil hot: 6 psi

I used to have a 1981 Dodge pick up with a 318. If I changed the oil and used the thin bulk oil we had at work (free!) the oil light would flicker when at hot idle. Raising the engine speed just slightly would turn the light off. The solution for me was to use thicker oil or add a can of STP with the thin oil. There was no singular thing wrong with the engine. It was just old and a bit worn. I sure wish I still had that truck.
I have some internal noise, similar to what coolcatcreative stated in post #22.

...the REAL reason was the lower end bearings - rod bearings and main bearings. (In the middle of a cross-country trip, one of the rod bearings went out completely, rod knocking and all...)
I tried to salvage it with new bearings (at the motel we stopped at) but by then the crankshaft was already damaged and after a few of miles of smooth running, the knocking came back...
I asked the mechanic who measured the oil pressure for me what he thought of my friend's proposal to change the rod bearings. He advised against it, saying he never had long-term success by replacing the rod bearings. The new bearings would perform fine, but some other bearing or internal component would fail within a year. That and I question just swapping the rod bearings, but not the main bearings. Wouldn't they all need to be changed?

Interesting about how some of you suggest abandoning the manufacturer's recommended 5W-20 weight oil and proactively moving to a heaver weight oil as the engine ages.
 

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And what do you think is going to happen if you switch to a 5W30? The manufacturer's recommendation was for a brand new engine with no wear issues. For whatever reason, you have a worn engine. A little heavier oil won't hurt anything. I actually used a 0W40 oil on my 2003 with no issues.
 

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Thanks for the specs and procedures.

I asked my mechanic to measure the oil pressure and listen to the engine as a second set of ears. These were his readings with the engine at idle (700 rpm):
Oil cold: 15 - 20 psi
Oil hot: 6 psi



I have some internal noise, similar to what coolcatcreative stated in post #22.



I asked the mechanic who measured the oil pressure for me what he thought of my friend's proposal to change the rod bearings. He advised against it, saying he never had long-term success by replacing the rod bearings. The new bearings would perform fine, but some other bearing or internal component would fail within a year. That and I question just swapping the rod bearings, but not the main bearings. Wouldn't they all need to be changed?

Interesting about how some of you suggest abandoning the manufacturer's recommended 5W-20 weight oil and proactively moving to a heaver weight oil as the engine ages.
He should of tested the pressure at higher engine speeds. The minimum pressure is 5psi at idle with the engine warmed up to operating temperature, and 30-80psi at 3000rpm.

Thicker oil would be one thing to try. Oil gets thinner as it heats up, and all the clearances inside the engine get bigger as the engine heats and expands.

The 5 in 5w-20 is the relative thickness of the oil cold, or rather 5W-20 behaves just like straight SAE 5 weight oil when it's cold. So it is very easy to pump on startup for a cold engine. The 20 in 5W-20 is the relative thickness of the oil at operating temperature, so the 5W-20 acts like a thicker 20W oil at operating temperature. The multiviscosity oils still thin as they heat up, but not as drastically as straight weighted SAE oil.

A 5W-30 multiviscosity oil would theoretically behave exactly the same at startup when cold as 5W-20, but would be thicker at operating temperature. A thicker oil will generate higher oil pressures, and will function better in a looser tolerance bearing. Large clearances need heavy oil, tight tolerances need thin oil.

I actually run 10W-40 in all my vehicles in Summer here in Dallas, Texas. We get 3-4 months of +100° highs and 80° nighttime lows, and only 1-2 weeks total of freezing temperatures. So 10W-40 in the summer half, and 5W-30 in the winter half. Similarly, you should have Summer Tires above 40°F, and Winter tires below 40°F, and the all seasons tires should go in the trash where they belong.

Chrysler made the 3.3/3.8 for 20-25 years, and they never recommended 5W-20 until later on, and they almost definitely did that for fuel economy reasons.
 
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Take a look at Walmart Super Tech 5W-40 Full Synthetic European Formula. Can't beat the price. Made by Warren Oil. Their products seem to test well.
I'm using it in my Jeep which has no oil consumption or pressure issues, but leaks at rear main seal some. I have also used it in a 2007 DGC 3.8L which had oil consumption issues.
10W-30/40 will be fine above freezing for your 2007 V6. I don't use 5W-20 for anything, not even my lawnmower.
 

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Discussion Starter · #30 ·
Since I get the brief noise at the first start of the day, should I stick with a 5W vs a 10W oil? The start-up sound is the same sound I hear after starting the car for the first time after an oil and oil filter change.

The mechanic was of the mind that with internal engine noise at 226,000 miles, there was not much value in checking the oil pressure. I had asked him to confirm the sensor was not kicking off a false reading, and that was about as much as he wanted to do for an engine that he considered a lost cause.
 

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Interesting about how some of you suggest abandoning the manufacturer's recommended 5W-20 weight oil and proactively moving to a heaver weight oil as the engine ages.
Unless I'm mistaken, 5w30 actually was the manufacturer's recommended oil weight until ~2004. Yet, the engine internals remained unchanged after that. That ought to tell you it's perfectly fine to use the slightly heavier oil.;)
 

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Since I get the brief noise at the first start of the day, should I stick with a 5W vs a 10W oil? The start-up sound is the same sound I hear after starting the car for the first time after an oil and oil filter change.

The mechanic was of the mind that with internal engine noise at 226,000 miles, there was not much value in checking the oil pressure. I had asked him to confirm the sensor was not kicking off a false reading, and that was about as much as he wanted to do for an engine that he considered a lost cause.
The oil pressure sensor switches at 2-4psi, 5 psi is the minimum recommended pressure at idle, and you allegedly have 6 psi. I've had or seen plenty of old Chevrolet straight sixes and V8s which are the same technologies as the pushrod 3.3L/3.8P V6's in our vans, that idled around 3psi without issues.

If the oil is leaking out when shut off such that it runs dry for a few seconds at startup, either you have some bad lower end bearings, a sloppy oil pump, or a bad oil bypass valve.

If it were me, I'd change the bearings out. You can easily drop the oil pan and reinstall it to access all of the bearings, and the bearings are maybe $20-$40 for the full set. Usually they'll get damaged before the crank journals do, but there's no telling until you open it up. A competent mechanic should be able to do it in a couple of hours or less, just swapping in new factory sized bearings.

If you have to pay for someone else to do it, and don't intend on keeping the van beyond a couple of years, it might not be worth it. Your lubrication system problems are not good for the engine, but it's probably not going to self destruct for a couple tens of thousands of miles either.
 

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Something internal changed in 2005, which is why 2005 and up burn oil. The 5w-20 was recommended to get the better gas mileage for CAFE standards. Heck, I've used 0w-20 in my 2004 with over 200,000 miles on it into the summer (full synthetic) with no noises or problems. I did replace my rod bearings at 192,000 miles chasing a vibration/slight uneven running issue. Did it in March, outside with snow still on the ground. New bearings from NAPA were about $36 at that time.

The main bearings will be much harder to change, because of the crosswise bolts through the sides of the block holding the main caps on. Some may be hard to access in the rear. There are two different torque specs for the rod bolts, depending on the type of rods you have (cracked with a bolt, or machined with a nut).

The mechanic sounds lazy if he doesn't even want to properly diagnose the issue (run the engine faster to check for proper running pressure). Probably wants the more expensive work of replacing the engine. :rolleyes:
 

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Something internal changed in 2005, which is why 2005 and up burn oil.
Pretty sure that only applies to the 3.8 and not the 3.3. My 3.3 is almost at 190k and at most, it used maybe one quart of oil within a 5k change interval. And, that was mostly before I fixed some small leaks it had.

The mechanic sounds lazy if he doesn't even want to properly diagnose the issue (run the engine faster to check for proper running pressure). Probably wants the more expensive work of replacing the engine.:rolleyes:
Agreed.
 

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Yes, the oil consumption seems to apply to the 3.8L V6 engine. The Jeep guys wrote volumes on their oil burning experiences with the 3.8L engine in their Wrangler JKs. Weren't too happy that Chrysler changed fron the 4.0L I6 in 2007.

 

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Yes, the oil consumption seems to apply to the 3.8L V6 engine. The Jeep guys wrote volumes on their oil burning experiences with the 3.8L engine in their Wrangler JKs. Weren't too happy that Chrysler changed fron the 4.0L I6 in 2007.
I don't blame them. Aside from the oil burning, the 3.8 was a gutless turd in a a Jeep compared to the 4.0. My neighbor had an '07 Wrangler. He ended up unloading it when it had around 40k on it because it was already using a ton of oil, and of course, Chrysler wouldn't stand behind the junk product they sold him. :rolleyes:
 

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Discussion Starter · #37 ·
The mechanic sounds lazy if he doesn't even want to properly diagnose the issue (run the engine faster to check for proper running pressure). Probably wants the more expensive work of replacing the engine.
The mechanic was upfront in making it clear hew was not interested in doing much diagnosing or any work on the vehicle. His contention was low oil pressure and the internal engine noise shows an engine at the end of its life. His thinking was engine repair or replacement would be a waste of money on a vehicle with body rust. And even if the vehicle was rust-free, in his experience, replacing rod bearings was a temporary bandage, that a high mileage engine with replaced rod bearings typically failed in the short term when the other high mileage parts on the engine failed, like main bearings.

If the oil is leaking out when shut off such that it runs dry for a few seconds at startup, either you have some bad lower end bearings, a sloppy oil pump, or a bad oil bypass valve.
When you say bad lower end bearings, do you just mean rod bearing like my friend suspects are bad? How does one pinpoint which of these three potential problem areas are causing the low oil pressure issue?
 

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Discussion Starter · #39 ·
C, so switch to 5W40, or 15W50, and drive on. And your mechanic is correct and certainly honest.
That's pretty much what I did yesterday. The heavier oil quieted the engine at the first start of the day and got the oil pressure up to where the oil light no longer illuminates.

I have another vehicle I can use (wife works from home) so when the van fails I will not have to rush to replace it. I hope that by waiting, the supply of vehicles will at some point increase and help moderate used vehicle prices.
 
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