I have a 3.5 VQ engine in my new pathfinder. I have read it somewhat is prone to sludging. Why do some engines seem to be more suseptible to sludge? Is it just knooks and crannies where oil seems to not flow? Is the VQ really know for sludging? My driving habits are between severe and regular. I do live in GA where it gets hot. I plan on going with the 7500 oci using M1 or PP and an OEM filter. I dont think this will be a problem. Where does the manufacture (oil and car) suggest the time (months) between oci fit in? Example Nissan 6 mo or 7500 mi or M1 guarantees 10k mi / 1 yr.
How is sludge formed?
- Thread starter stygz
- Start date
- Status
Oil sludges when exposed to high heat.
This can be due to owner neglect in changing oil.
Some engines are prone to sludge. This is due to their design where oil is exposed to extreme hotspots, either due to poor cooling of the engine block (localized) or too small oil passages.
I would definitely use synthetic oil in an engine prone to sludge. In fact I use synthetic oil in all my cars.
Pennzoil ULTRA is one of the best cleaning oils.
This can be due to owner neglect in changing oil.
Some engines are prone to sludge. This is due to their design where oil is exposed to extreme hotspots, either due to poor cooling of the engine block (localized) or too small oil passages.
I would definitely use synthetic oil in an engine prone to sludge. In fact I use synthetic oil in all my cars.
Pennzoil ULTRA is one of the best cleaning oils.
Last edited:
To follow on to what Corvette Owner said, sludge is decomposed oil that has been exposed to oxidation. Sludge is like suspended or deposited carbon chain particles that have little lubrication value, and can be somewhat abrasive and hamper the heat transfer process that keeps the hottest components from getting even hotter. It happens from exposure to high temperatures, is aided by fuel & contaminant dilution, and is typically sourced where the exhaust valve parts contact the oil and the hot parts on the pistons and rings. Sludging is a process that accumulates with time.
Oil with higher volitization temperature/ lower NOACK rating value is usually more resistant to producing sludge. It's usually found due to properties of the blend of an oil's base oils, where those with the better base oils such as group 3+, 4 and 5 (semi- and true synthetics) produce the best anti-sludging results. This allows longer OCIs (oil change intervals) before an unacceptable amount of sludge builds up.
Engines which are more likely to cause sludge typically are compact, hotter running, have higher levels of combustion blowby, and in many cases are internally dirty and neglected.
Oil with higher volitization temperature/ lower NOACK rating value is usually more resistant to producing sludge. It's usually found due to properties of the blend of an oil's base oils, where those with the better base oils such as group 3+, 4 and 5 (semi- and true synthetics) produce the best anti-sludging results. This allows longer OCIs (oil change intervals) before an unacceptable amount of sludge builds up.
Engines which are more likely to cause sludge typically are compact, hotter running, have higher levels of combustion blowby, and in many cases are internally dirty and neglected.
On my vehicles I have been pretty religous on the o/c. My 08 Impreza gets o/c every 8 mo or 7500 mi. I would consider the Impreza as severe use. Subaru states you can go with the longer 7500 oci using a syn oil. It has gotten Either Mobil 1, Pennzoil Platinum, or Pennzoil Ultra since 10k miles (we got the car new). Before that the dealer used motorcraft syn blend. My Pathfinder was also purchased new with only one o/c under its belt. It was done at the dealer as it was free. They put in Valvoline syn blend. I am a believer in syn oils, even planning on M1 in my new Honda HRX mower. I Think I stay of top of the o/c and should not have any sludging issues. Not sure If I will use M1 or Mobil 1 Extended Performance in the Pathfinder. I have never used the EP version.
Think of sludge formation as something akin to an old style oil paint curing on the wall. It goes from a liquid to a solid due to the presence of double bonds which undergo a free radical polymerization. In paints, you want this to happen and "driers" or chemicals that promoted the polymerization were added to speed the process. It is also accelerated by heat.
In oils, you will have a certain amount of double bonds and other types of reactive carbon sites that can promote the same type of polymerization leading to the formation of a solid material that we call sludge. Old group I and II oils had lots of these double bonds but as engines got hotter and the desire for extended oil change intervals grew, refining processes changed to eliminate more and more of these reactive sites. High pressure hydrogen additon is one method. So now with group II+/III oils that are "severely hydrotreated" and the use of synthetic oils such as PAOs and esters that contain no double bonds, the tendency to form sludge is SIGNIFICANTLY lessened.
The above posts tell you why certain engines are more prone to sludge formation....HEAT and POOR DESIGN. Your best weapon against sludge in such an engine is to use a good oil that is either a Group III, IV or V or a blend thereof and to make sure that oil changes are done on time.
In oils, you will have a certain amount of double bonds and other types of reactive carbon sites that can promote the same type of polymerization leading to the formation of a solid material that we call sludge. Old group I and II oils had lots of these double bonds but as engines got hotter and the desire for extended oil change intervals grew, refining processes changed to eliminate more and more of these reactive sites. High pressure hydrogen additon is one method. So now with group II+/III oils that are "severely hydrotreated" and the use of synthetic oils such as PAOs and esters that contain no double bonds, the tendency to form sludge is SIGNIFICANTLY lessened.
The above posts tell you why certain engines are more prone to sludge formation....HEAT and POOR DESIGN. Your best weapon against sludge in such an engine is to use a good oil that is either a Group III, IV or V or a blend thereof and to make sure that oil changes are done on time.
Last edited:
Aren't there several ways that sludge form? I know high heat is one way, but I've also read that the depletion of dispersants and the overloading of oil with contaminants is also where some types of sludge form. Some engines are known as sludge monsters primarily when the oil isn't changed at severe service intervals.
MolaKule
Staff member
Quote:
A. Black Sludge is defined as thick to solid material with low water content, of dark color, light oil insolubles,
and typically found in rocker cover, cylinder head, timing chain cover, oil sump, oil pump screen, and oil rings in variable quantities.
B. Cause of Black Sludge in more modern engines.
1. Promoted by mixed driving conditions in which there is stop and go and highway operations.
2. Starts with Nitrous oxides in Lean-Burn engines reacting with blow-by gasses.
3. High spark advance, high temperature of combustion, lean fuel/air ratios, high compression.
4. Fouled air ventilation systems (PCV), combined with low operating temperature driving conditions.
5. Longer oil change intervals.
6. Higher oil temperatures.
7. Lower sump capacity.
Sludge Discussion
A. Black Sludge is defined as thick to solid material with low water content, of dark color, light oil insolubles,
and typically found in rocker cover, cylinder head, timing chain cover, oil sump, oil pump screen, and oil rings in variable quantities.
B. Cause of Black Sludge in more modern engines.
1. Promoted by mixed driving conditions in which there is stop and go and highway operations.
2. Starts with Nitrous oxides in Lean-Burn engines reacting with blow-by gasses.
3. High spark advance, high temperature of combustion, lean fuel/air ratios, high compression.
4. Fouled air ventilation systems (PCV), combined with low operating temperature driving conditions.
5. Longer oil change intervals.
6. Higher oil temperatures.
7. Lower sump capacity.
Sludge Discussion
MolaKule
Staff member
Quote:
Is the VQ really know for sludging? My driving habits are between severe and regular. I do live in GA where it gets hot. I plan on going with the 7500 oci using M1 or PP and an OEM filter.
The VQ is not a sludger, but it does run hot.
On the positive side it does have about a 5.5 qt. capacity with filter change. I prefer PureOne filters.
If you do NOT do occasional highway driving, use the 3,750 OCI at least for the first 10,000 miles or so.
Is the VQ really know for sludging? My driving habits are between severe and regular. I do live in GA where it gets hot. I plan on going with the 7500 oci using M1 or PP and an OEM filter.
The VQ is not a sludger, but it does run hot.
On the positive side it does have about a 5.5 qt. capacity with filter change. I prefer PureOne filters.
If you do NOT do occasional highway driving, use the 3,750 OCI at least for the first 10,000 miles or so.
Originally Posted By: MolaKule
Quote:
Is the VQ really know for sludging? My driving habits are between severe and regular. I do live in GA where it gets hot. I plan on going with the 7500 oci using M1 or PP and an OEM filter.
The VQ is not a sludger, but it does run hot.
On the positive side it does have about a 5.5 qt. capacity with filter change. I prefer PureOne filters.
If you do NOT do occasional highway driving, use the 3,750 OCI at least for the first 10,000 miles or so.
Thanks for the tip. On my first o/c I did get in 2 hwy trips. One was about 1k round trip and the other was about 300 mi.
If the VQ runs hot M1 should add reassurance on the 7500 oci.
Quote:
Is the VQ really know for sludging? My driving habits are between severe and regular. I do live in GA where it gets hot. I plan on going with the 7500 oci using M1 or PP and an OEM filter.
The VQ is not a sludger, but it does run hot.
On the positive side it does have about a 5.5 qt. capacity with filter change. I prefer PureOne filters.
If you do NOT do occasional highway driving, use the 3,750 OCI at least for the first 10,000 miles or so.
Thanks for the tip. On my first o/c I did get in 2 hwy trips. One was about 1k round trip and the other was about 300 mi.
If the VQ runs hot M1 should add reassurance on the 7500 oci.
Through ignorance, laziness, and frugality.
I know way too many people who think gasoline ad wiper fluid is the only 2 fluids that ever have to go into their BMW's and similar autos. On the other side of the coin, I know others who have the most beat up cars and they are better maintained than Lambo's.
I know way too many people who think gasoline ad wiper fluid is the only 2 fluids that ever have to go into their BMW's and similar autos. On the other side of the coin, I know others who have the most beat up cars and they are better maintained than Lambo's.
Originally Posted By: hardcore302
Through ignorance, laziness, and frugality.
I know way too many people who think gasoline ad wiper fluid is the only 2 fluids that ever have to go into their BMW's and similar autos. On the other side of the coin, I know others who have the most beat up cars and they are better maintained than Lambo's.
Through ignorance, laziness, and frugality.
I know way too many people who think gasoline ad wiper fluid is the only 2 fluids that ever have to go into their BMW's and similar autos. On the other side of the coin, I know others who have the most beat up cars and they are better maintained than Lambo's.
Originally Posted By: hardcore302
Through ignorance, laziness, and frugality.
I know way too many people who think gasoline ad wiper fluid is the only 2 fluids that ever have to go into their BMW's and similar autos. On the other side of the coin, I know others who have the most beat up cars and they are better maintained than Lambo's.
Funny story, had a young guy probably 20 bring in a Land rover that was about 2 years old.. Lot of highway miles has 75k.. He asked for us to set tire pressure and add washer fluid.
So as a courtesy I checked his coolant, and pulled his dipstick, all that came out on the stick was sludge.
We asked when his last oil change was done. He laughed and said he didn't think it needed one, and it hasn't had one..
Well we told him it needed one.. So he said ok how much.. Told him it was suggest by LR to use a synthetic, he freaked, so no give me the cheap stuff.
Dropped the plug.. Nothing came out.. Poked a screw driver in, sludge.. All sludge.. Flushed about 10 qts f oil in the fill and right out the drain pan.. Was so bad..
3 months later, had a new one.. Asked what happened with the old one.. He traded it in...
Through ignorance, laziness, and frugality.
I know way too many people who think gasoline ad wiper fluid is the only 2 fluids that ever have to go into their BMW's and similar autos. On the other side of the coin, I know others who have the most beat up cars and they are better maintained than Lambo's.
Funny story, had a young guy probably 20 bring in a Land rover that was about 2 years old.. Lot of highway miles has 75k.. He asked for us to set tire pressure and add washer fluid.
So as a courtesy I checked his coolant, and pulled his dipstick, all that came out on the stick was sludge.
We asked when his last oil change was done. He laughed and said he didn't think it needed one, and it hasn't had one..
Well we told him it needed one.. So he said ok how much.. Told him it was suggest by LR to use a synthetic, he freaked, so no give me the cheap stuff.
Dropped the plug.. Nothing came out.. Poked a screw driver in, sludge.. All sludge.. Flushed about 10 qts f oil in the fill and right out the drain pan.. Was so bad..
3 months later, had a new one.. Asked what happened with the old one.. He traded it in...
The VQ can most certainly sludge on conventional oil because it runs hot. That alone makes it a good candidate for synthetics.
From what I've read on this forum, certain cars with poorly designed PCV systems
were prone to sludging. That would translate into a lack of proper ventilation.
Engines need to be vented to atmospheric pressure at all times.
were prone to sludging. That would translate into a lack of proper ventilation.
Engines need to be vented to atmospheric pressure at all times.
The add pack can only take so much... beyond that it can't take it anymore.
My armada has a VQ56 a relative of your VQ35. I use synthetic at 7.5-8k intervals and the engines looks spotless through the fill hole.
Originally Posted By: stygz
I plan on going with the 7500 oci using M1 or PP and an OEM filter. I dont think this will be a problem.
I think that's sensible. If you were going the severe service OCI, I'd recommend conventional.
I plan on going with the 7500 oci using M1 or PP and an OEM filter. I dont think this will be a problem.
I think that's sensible. If you were going the severe service OCI, I'd recommend conventional.
Well it looks like the the Pathfinder will get Mobil 1. I found some on sale at my base exhange for $4.49 a qt....plus not tax! Not sure If I will stock up or not. Also I will register my Pathfinder for the Pennzoil warranty and get the $20 rebate on a $25 PP 5qt jug at Walmart. I will probably use the PP for our Impreza as that is what it has been getting for the last 2 years. I will also pick up a qt of Mobil 1 10w30 for the Honda HRX lawnmower. I will also take advantage of the Mobil 1 rewards and get a new coffe mug for the new Pathfinder! That should set me up for the next year.
- Status
Similar threads
- Locked
