Sludge is a term I hear mentioned on most oil commercials nowadays. Company after company claims their oil prevents sludge. Is this merely marketing hype? What exactly is "sludge" and how is it created? Are there oils on the market which are truly better at "cleaning" out the inside of your engine? When someone claims good results from an oil, what does that actually mean?
Engine Sludge
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Oils contain additives that neutralize acids. When these neutralizing properties have been depleted, a substance known as sludge develops. An oil analysis can tell how much total base number or TBN is remaining. This TBN tells the level of active additive that can neutralize the acids. As far as I know, no one has posted or even analyzed "sludge"; therefore, what it is exactly is hard to say. I have seen from personal experience that Pennzoil Ultra really does clean the inside of your engine. My '99 Corolla has 120,000 miles with the previous owner, I suspect, running long intervals with conventional oil. Before running the Ultra, I had varnish stains on my dipstick, however, now the varnish is gone. I also noticed a thin layer of a sludge-like substance on the bottom of the pan that I drained my used oil into. I have always been hesitant to use Pennzoil products(as a previous Castrol fan), I am sold on the Ultra. To answer your last question, if your oil analysis results are within the expected ranges(e.g. for lead, copper, etc.)and thereby showing low engine wear for a certain extended mileage run on the oil, in my opinion that is a "good result".
Sludge seems to be the breaking down and "Globbing" of Old, heated Oil that hasnt had its acid neutralized into a tar-looking, sticky or hard, coating, on engine innards. A little more serious than Varnish which is just a stain.. it may cause issues, some are really bad. The fear is, a piec of "Sludge" can break off and act as a rock flung at x-thousand number of RPMs into a valve, killing it. Some people try "Engine flushes" if they are brave, to dislodge it and simply have it come out of the fill hole. Though ive never heard of an engine "Dying" that way, many like other things. Its a weird thing, sludge.
Redline, Royal Purple, and Mobil 1 0W-40 all clean the inside of an engine very well they just wont tell you they do. Pennzoil Platinum is not as agressive as Ultra, but it comes in grades Ultra does not and also does a great job.
There are those that will say Sludge cleaning isnt necessary. There is also this thing called Auto Rx that you can use with Castrol Syntec or a conventional oil, that will clean at least as good as and some say better than Ultra.
The logic, also, is that more sludge = higher heat = inneficient engine = more sludge = more wear/money/gas, repeat. Putting MMO in the gas, though i does not touch the oil, also helps "Clean sludge" though not if the Oil type, IIRC. MMO in GAS does no harm, and MMO in Oil SEEMS to not either, though it may not be needed. Maybe. It may have benefits, some hate it because its not Oil. The answer will take a LOT of reading, but its an "Approved sludge lessener" for way less than MMO.
Synthetic also claims to have "Beaten sludge," unofficially, fro the synthetic aficionados (Group III or whatever group, Castrol Syntec is Group III for ARX use it can work) in that many synthetic engines dont seem to have any where it was used, though someone else is quite good at saying "Its synthetic so what" and it makes for compelling debate and ponderance.
Sludge is preventable. Change your oil and filter. Oils have additives that clean. Some are better than others. Read the used oil analysis section!
No hype here... sludge happens:
https://bobistheoilguy.com/forums/threads/bmw-sludge-pictures.121578/
https://bobistheoilguy.com/forums/threads/sludge-in-ford-explorer-4-0-sohc.122660/
https://bobistheoilguy.com/forums/threads/sludge-in-ford-explorer-4-0-sohc.122660/
https://bobistheoilguy.com/forums/threads/sludge-in-ford-explorer-4-0-sohc.122660/
No hype here... sludge happens:
https://bobistheoilguy.com/forums/threads/bmw-sludge-pictures.121578/
https://bobistheoilguy.com/forums/threads/sludge-in-ford-explorer-4-0-sohc.122660/
https://bobistheoilguy.com/forums/threads/sludge-in-ford-explorer-4-0-sohc.122660/
https://bobistheoilguy.com/forums/threads/sludge-in-ford-explorer-4-0-sohc.122660/
Would it then be fair to say that to prevent sludge, whatever oil one chooses to use should be changed regularly along with filter? I realize that some engine designs and applications call for specific type of oil i.e. luxury imports, dodge srt and other souped up domestics. My question merely pertains to average joe passenger car.
Sludge is simply a byproduct of oil and heat.
Better oils, cooler engines, shorter OCIs all help prevent sludge.
Better oils, cooler engines, shorter OCIs all help prevent sludge.
Originally Posted By: outoforder
Would it then be fair to say that to prevent sludge, whatever oil one chooses to use should be changed regularly along with filter? I realize that some engine designs and applications call for specific type of oil i.e. luxury imports, dodge srt and other souped up domestics. My question merely pertains to average joe passenger car.
Yes, that would be fair to say. In most cases sludge forms because of neglect, although some engines have been worse than others. But regular, on time OCIs will go a long way to prevent the formation of sludge.
Would it then be fair to say that to prevent sludge, whatever oil one chooses to use should be changed regularly along with filter? I realize that some engine designs and applications call for specific type of oil i.e. luxury imports, dodge srt and other souped up domestics. My question merely pertains to average joe passenger car.
Yes, that would be fair to say. In most cases sludge forms because of neglect, although some engines have been worse than others. But regular, on time OCIs will go a long way to prevent the formation of sludge.
I've been told that using a different brand of oil at every change can cause sludge. Any truth to this?... As for the manual, I bought the car used and the old lady lost the manual. I change my oil every 5000 or less. Budget is tight, looking to use a cheaper priced oil.
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Originally Posted By: outoforder
I've been told that using a different brand of oil at every change can cause sludge. Any truth to this?
No more truth than using a different brand of gasoline every fill up will cause lowered gas mileage.
I've been told that using a different brand of oil at every change can cause sludge. Any truth to this?
No more truth than using a different brand of gasoline every fill up will cause lowered gas mileage.
The #1 cause of sludge is bad PCV [positive crankcase ventilation].
Faulty parts, or bad design.
#2 is OCIs [oil change intervals] that go too long.
Faulty parts, or bad design.
#2 is OCIs [oil change intervals] that go too long.
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