We Are Obsessed But Does It Really Matter

[Jackson_Slugger]

You mean yet another seagull post?

 

[slo town]

You mean yet another seagull post?

I confess that I don't know what that means.

Scott

 

[CarbonSteel]

I confess that I don't know what that means.

Scott

You know...a seagull that flies in, dumps a load, then flies away and never returns. Fairly consistent behavior...

 

[aquariuscsm]

I'm curious . How many people do you know that had an engine blow up because of a Quick Lube place ? I've never met one myself . I've read a lot of stories on the Internet though ...

Me, not a single one. I'm honestly one of the very few people I know who changes their own oil.

 

[aquariuscsm]

Great, then maybe someone can explain why every real world study shows that the vast majority of engine wear takes place in the first 20 minutes of engine operation from a cold start...

My theory is that the metal parts haven't fully expended from the lack of heat, and haven't perfectly mated to each other yet. But has nothing to do with the oil.

 

[aquariuscsm]

Here is your question, I like Motorking’s answer.
https://bobistheoilguy.com/forums/threads/can-too-thick-of-oil-be-damaging.295900/

Motorking could not be more wrong.

 

[Bill_W]

Motorking could not be more wrong.

He was there… You were not. I am sure it threw a code if the car went into limp mode.

 

[coolformula]

I think changing your oil "often" 5-8k miles using a the kind your car needs (10-40W etc) is key.

All these is more nerd or academic in the purpose of our discussions (please don't flame me).

Hope everyone has a great 2023!

 

[ZeeOSix]

Not so… Pressure is applied to parallel oil branches. If there is less resistance the flow will go there. Bearings just need feed pressure and create its own pump pressure. The main oil pumps purpose is to feed lubrication after it’s initial PSI to a ambient pressure location and that is where the lubrication is needed.

The oil pressure seen in an engine is the result of the PD pump trying to force it's output oil volume through all the force fed journal bearings (crank, rods, cams) ... they create the majority of an oiling system's flow resistance to the pump, and therefore oil pressure is created. Journal bearings move oil flow through themselves based on both their rotational speed and the oil viscosity, and also the feed pressure from the oil pump adds to the bearing total flow volume - so total flow volume through the bearing is rotational flow + feed pressure flow. Any well designed and healthy PD oil pump is going to ensure more than adequate oil flow to the oiling system, especially at high RPM when the pump volume is typically way higher than the minimum required (see graph in post #39). The added oil flow through the bearings due to the pump feed pressure helps keep the oil temps down inside the bearings.

The faster the bearing rotates, the more oil it flows, and also the faster a bearing is rotating, the more oil flow volume is leaving a PD pump due to increased engine RPM which is also being forced through the bearings. The faster a journal bearing rotates, the larger the MOFT becomes as the journal tries to self center itself within the bearing diameter (all other factors held constant). Also, the faster the bearing rotates the more heat is produced from oil shearing inside the bearing. So what this boils down to is that the worse thing for a journal bearing is a low oil viscosity combined with low engine RPM while "lugging" the engine at low RPM. That combination creates a small MOFT. And if low RPM lugging was done after the oil got extremely hot for some reason, then that's even worse. The second worse thing for a journal bearing is using an oil with a HTHS that is too low to maintain adequate MOFT as the oil heats up from high RPM shear within the bearing, like running an engine real hard on a race track, or doing extended towing under high loads in high temperatures for extended periods. High loads in the cylinders and rods also causes a decrease in MOFT at certain crankshaft angles - that's part of the "lugging" factor at low RPMs that should be avoided.

The main goal is to always maintain some MOFT headroom to ensure that metal-to-metal contact in the journal bearings is not happening during all driving conditions. That can be done by keeping the oil temperature down, and/or using a higher viscosity, higher HTHS oil. There is a direct correlation between oil temperature (HTHS viscosity), engine RPM and MOFT. MOFT headroom is good, zero MOFT is bad ... it's simple.

 

[ZeeOSix]

Thanks… I was looking for that figure. The big chunk is main bearings. Second is piston jets. The oil pump relief starts around 2000 RPM. Higher viscosity would be less flow due to pump relief and that is higher bearing temp. You cannot use engine oil pressure reliable with oil bypass happening..

Even if the pump is in pressure relief at say 90 PSI at oil temperature of 100 C, there will still be more flow than needed going through the oiling system if the oiling system engineer knows how to specify an oil pump for the engine it's feeding. As the oil temperature increases, it becomes harder to get the pump to hit pressure relief. I highly doubt guys doing track days are hitting pressure relief when the oil is at 250-280F.

 

[ZeeOSix]

According to the article the tight bearing clearance requires thinner oil. Also it is not just tight bearing clearance but the crank needs perfect balance. (blueprinting crank back in my time) Hardware fix required there too.

Most production engines on the street have around 0.0015-0.0025" bearing clearance. Therefore, a thin oil still works, but as the graph below shows, a thicker oil still gives more bearing MOFT even in tighter bearings.

 

[M104]

The only difference i've been able to notice is that A3/B4 oils seem to clean a dirty engine a bit more than A3/B3 over the years. Other than that, in my engines, as long as there's oil in the sump there's no difference. I've stopped chasing fuel economy through oil a long time ago after doing my best tanks on 15W40. I used to own a diesel Mercedes that is still on the road with over 500k km, 15k km oil changes with the cheapest 10W40, the body is rotting away and the engine still starts at the first rotation of the crank, has good compression and burns close to no oil. Oil is overrated. (not saying you shouldn't have some in your sump)

 

[KEVINK0000]

It's not just vapours, it's a combination of several factors:
1. Parts that don't fit properly
2. Excessive start-up enrichment
3. Poor atomization
4. Poor combustion
5. Heat-activated additives that haven't reached activation temperature

That's why calling it "startup wear" is a misnomer. I believe @kschachn touched-on it earlier in the thread, but it's really warm-up wear, and it's a period during which the engine is working toward getting normalized, and while in that state, wear is elevated.

BTW, a heavier oil will be heated more quickly; will generate more heat, due to the shearing action of the pump and bearings. It has nothing to do with the polymers.

If you are on the pump relief, yes, there is a difference in flow, if you aren't, there isn't.

As you noted, the fitment of oil/coolant heat exchangers has been a huge improvement, bringing oil up to temperature much quicker and keeping it where it should be. This also aides in facilitating the use of thinner oils by controlling viscosity through temperature.

Glad someone brought this up. I believe this is the correct way to state the facts of initial startup wear.

If the oil isn't warm (normal temp), the engine isn't either.

 

[KEVINK0000]

Oils change colour for a number of different reasons, one of them is carbonaceous materials as a result of incomplete combustion, this was very common with carburetors. At the same time, yes, you have the other nasty byproducts of this process (including the vapours you mentioned) making their way past the rings into the sump.

However, the reason these things are getting by the rings is #1. Ring seal is poor during warm-up (but improves as warm-up takes place) as is piston fitment due to change in shape and size when cold vs at proper operating temp.

So, you take excessive startup enrichment, poor atomization and poor combustion characteristics, all of which produce more nasty byproducts, including the one you mentioned, and then you put it in a cylinder that isn't being properly sealed, you create a recipe for a not-insignificant component of that to end up in the pan. The engine doesn't stop producing acids and other nasties once warm, but their ability to migrate into the oil pan is greatly reduced. On top of that, you have some of your additive AW chemistry that hasn't hit the activation temp yet and this is going to present as an increase in wear.

Amusing anecdote: Our Expedition used to produce pretty clean oil, despite being idled regularly for warm-up in the winter and having a ton of miles on it. You could always see through it on the stick. Both our HEMI's, but the 6.4L in particular, makes the oil very black, very quickly. This isn't due to idling it, but a function of this particular engine architecture (hence why it has dual ignition) that results in carbonaceous material being generated at low engine speeds, something the Modular didn't have an issue with.

DI, which produces soot, has made this issue far, FAR worse, hence we see its "signature" on the rear valances of many cars.

Per the drop of water note, this happens in cold climates during the winter even when the engine is fully up to temperature. If the exhaust system isn't hot enough to keep the water as steam, it will condense. Water is a natural byproduct of combustion, regardless of the engine's state of warm-up (from just starting to fully at operating temp).

It’s not the DI that’s producing that soot, that is the result of very rich mixture under boost. I don’t think you will find a NA DI engine car with the same residue. Which has always interested me from an emissions standpoint. Open loop is a license to pollute apparently.

 

[wemay]

Most production engines on the street have around 0.0015-0.0025" bearing clearance. Therefore, a thin oil still works, but as the graph below shows, a thicker oil still gives more bearing MOFT even in tighter bearings.

View attachment 132887

Thanks for the graph ZeeOsix but I don't know many people (except a few here LOL) upping their viscosity from a 0w20 to a 10w60, 15w40 or 20w50.

When looking at the difference between 0w20 and 10w30, it appears to be very small. Plus, we don't know where in their specific hths ranges these sampled oils fall. I'd be more interested in one comparing 5w30 (3.0 hths)to a 20 (2.6). If I find something, I'll post.

 

[KEVINK0000]

If the postings from my fellow owners of 20+ year old Jags are any indication, the fatal issues with older cars are primarily worn out complicated electronics, not engine wear.


These older cars are at the bottom of the depreciation barrel and not worth spending thousands on new computer and other electronic components. Some people are finding places that can repair these type parts, but that’s the exception, not the rule.

Back to the topic, on modern cars I know about engine wear does not seem to be an issue in any case up to the 400,000 mile mark. There are however too many examples of newly designed engines that turn out to be oil consumers and worse.

Perhaps the engineers that designed them lied about their resumes like did the newly elected US Congressman from Long Island.

Z

You have done this before.

Please stop injecting politics into this discussion. We have enough of that just about everywhere else.

 

[1 SX]

For me its more so of keeping the engine at optimum efficiency and performance for the longest time possible... Yes it will wear, but hopefully slower and will have power for longer ect... I don't see this 2.4L making 500K, But a solid 300K with no oil consumption with decent performance still would be a really nice plus.

EDIT: Wait.. is this a thin vs thick thread?

Anyways I use 5W30 all year in both 2.4l..

Factory spec for 5W20..

 

[TiGeo]

To the OP - no, I don't think it actually matters for the vast majority of drivers driving their vehicles in "normal" conditions. Regular 5-10K oil changes with basically whatever oil (I do think you should use an oil that has the approvals/specifications that the manufacturer calls for) should get most people well into the ownership years/mileage they are looking for - most folks don't keep their vehicles 10 years/100K. Towing. Track. Heavy duty all day stop/go. That's the use where things go sidewaways but even then....it probably doesn't matter if you just decrease your intervals/change it more frequently. Oil and maintenance are like any other thing related to cars by enthusiasts...some take it to the nth degree b/c they can/want to...not b/c they need to.

 

[bullwinkle]

How does that happen?

The water droplets are from the cat initially lighting off, before the exhaust gets hot enough to vaporize it into steam. I’ve had a few Hondas that were somewhat short tripped, cat in the front, muffler mounted horizontally in the back with no drain hole. They did not last very long…

 

[bullwinkle]

Glad someone brought this up. I believe this is the correct way to state the facts of initial startup wear.

If the oil isn't warm (normal temp), the engine isn't either.

Piston slap means aluminum piston and cast iron block haven’t expanded and gotten the proper clearance yet, I would think that aluminum, iron, and chromium (from rings) might wind up in the oil due to cold start wear.