I have a quick question that may have been talked about before, not sure. but anyways, people like to talk about one oil keeping an engine cleaner than another and so on. my question is, does it really matter if one oil theoretically would keep and engine cleaner if you are going to change said oil at 3000 miles anyways? assuming your using a synthetic oil, would cleanliness be the same between the major brands like pennzoil, mobil, Valvoline etc? I understand some oils may be better or worse if doing extended drains, but if your changing at 3000k miles does it really matter?
engine cleanliness
- Thread starter skippermatt
- Start date
Answer: nope. Unless you’re idling for half those miles.
It can absolutely matter. Piston deposits can not be remedied by oci length. If your vehicle is prone to piston deposits 3k oci’s will not fix it. In fact most piston deposits occur early in the oci. A high quality oil can prevent piston deposits or an oil like Restore and Protect.
Not at all. Unless you have an engine with a known piston ring fouling problem.
there you have it OP, absolutely yes, and absolutely not...
It depends on the engine and the operating conditions, and yes some oils are better than others. Blanket statements can get people in trouble around here.
On a daily driver I would think it would NOT matter. Btw, oils are generally designed to run clean as in not leave deposits rather than remove existing deposits.
An understandment to say the least.
Depends on engine, use, fuel, OCI, etc. No one can answer this question with a definitive answer for you.
That being said, if you were to use a synthetic oil, and change the oil every 3000 miles, you would be doing better than most people, and would likely never have a lube related issue. Unless you are in the extreme, such as multiple short trips without warm up daily, then no oil will suffice.
There are followers here from all camps, and will get mixed opinions.
I am far from an expert, but from years of reading and messing around under the hood I have "conclusively" determined that Pennzoil, Quaker State, Castrol, Mobil 1, Valvoline, or any major store brand full synthetic oil of the correct viscosity with appropriate approvals all work about the same with a 3-5k OCI. Boutique oils won't provide much benefit at this OCI but may be a better choice for longer OCIs or special situations.
OTOH the recently released cleaning specialists (HPL, Valvoline Restore and Protect, Mobil 1 Advanced Clean, etc) may work miracles for existing deposits. Valvoline Restore and Protect removed some deposits on my Honda that the other oils left behind, but whether or not that is meaningful is another discussion - I only have 195k miles on the van and most OCIs were 5k with whatever synthetic was on sale (often a frankenblend of brands and viscosities). Only in the past year did it see Valvoline Restore and Protect.
OTOH the recently released cleaning specialists (HPL, Valvoline Restore and Protect, Mobil 1 Advanced Clean, etc) may work miracles for existing deposits. Valvoline Restore and Protect removed some deposits on my Honda that the other oils left behind, but whether or not that is meaningful is another discussion - I only have 195k miles on the van and most OCIs were 5k with whatever synthetic was on sale (often a frankenblend of brands and viscosities). Only in the past year did it see Valvoline Restore and Protect.
Last edited:
Somewhat engine dependent but yes It matters mainly because it can foul the rings and in some cases valves.
But only if you keep the car long enough - which most people don't.
So no - it won't matter for most people.
But only if you keep the car long enough - which most people don't.
So no - it won't matter for most people.
- Joined
- May 28, 2014
- Messages
- 2,596
I've never had to use any sort of "engine cleaner".
Never had any engine troubles or failure either.
Never had any engine troubles or failure either.
Patman
Staff member
I’m not singling you out here but I just wanted to point out that a lot of people say that but they also may have never put high enough mileage on any of their cars that it would see a problem. If you have never had a car with over 200k on it then engine cleanliness isn’t really a big enough issue to cause a failure. But if you’re the type to go 250k+ that’s perhaps where you’re going to see bigger differences between different oils. I think the potential for failure becomes greater at higher mileages if your oil isn’t doing a good enough job. (And obviously some engines are not as susceptible to getting dirty than others just by their design as well)
"does it matter" is a value judgment that you can only make for yourself.
My suggestion is that it's possible for 3000 mile OCI to actually make an engine dirtier than 5000 mile OCI and potentially even 10k OCI, and this can be worse with some oils than with others. It's probably worse with lighter grade group III oils and much better with light grade PAOs.
People tend to think of fresh oil changes as constantly replenishing the detergents in the oil, but they forget that fresh oil is also replenishing the lightest, most volatile and reactive parts of the oil that will be your source of deposits as well.
So it is not at all the case that simply changing oil very frequently is a panacea of engine cleanliness. What matters is the quality of the additive pack in that oil and the quality of the base oil blend in its oxidation resistance.
The key to engine cleanliness is 1) oil temp that allows the detergents to perform optimally, 2) lowest possible oxidation, 3)enough heat to keep moisture and dilution from accumulating.
It's tempting to think that constantly refreshing oil is a great way to have cleanliness, just like it's tempting to think that cold oil is the path for low oxidation because colder oil, by itself, oxidizes much less. But it turns out that cold oil also means a cold engine, which means blowby, dilution, moisture, and sludge precursors in an oil that is less chemically active and able to manage all that contamination load.
As a result, cold oil temps tend to mean FASTER oil degradation, not slower, when you account for the entire system effects.
This is how someone can end up with stuck rings in a VW/Audi engine while using an oil tested to MB229.5 or Porsche A40 or LL-01. These stringent specs assure that oil resists high temperatures.
But what test measures resistance to cold temps? To prolonged fuel dilution and combustion blowby? What happens when instead of torturing the oil with track days and autobahn runs, you torture it with 5 months of winter operation in an engine where the thermostat spends very little time open? It just as much torture, but it's a torture almost no standards are testing or validating.
Stringent specs only validate to the condition of the spec. And when that spec is not representative of your usage, it can lead to a false confidence.
So instead of saying "oil doesn't matter, change every 3k" I would suggest that of course the oil matters, which is why you want to choose a 10k capable oil if you can demonstrate that an oil is 10k suitable for you (via used oil analysis).
So, where is this "dirt"?
- Joined
- May 28, 2014
- Messages
- 2,596
95 Explorer - 215,000 miles before it was sent to scrap yard with bad rack and pinion
96 Crown Victoria - over 300,000 miles
Front end suspension failed because of rust issues as well as frame.
75 Malibu - front end collision
Miles on car was at least 200,000 plus
3 vehicles from the past years
Explorer- oils used were Kendall and Royal Purple HPS
Crown Victoria - oils used were Motorcraft, Mobil 5000
Malibu - oil used was Havoline oil
Last edited:
Lots of variables, but in general 3K changes will prevent the worst case from ever happening. Personally I do 5K changes with filter every other time (on the 10's). Never had any issue the past 45 years.
Similar threads
- Locked