What Acids?
- Thread starter wn1998
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Acids are formed by combustion but they are then neutralized by the additives in the oil.
The active acid neutralizing capability of the engine oil is expressed as TBN. The TBN is rarely depleted in 3 months or less.
The active acid neutralizing capability of the engine oil is expressed as TBN. The TBN is rarely depleted in 3 months or less.
1. Show your UOA data that proves conclusively that they're full of it.
2. Ask them for the real data upon which they base their short OCI opinion. You will be met with silence.
3. Refer them to our UOA section. Invite them to find a group of UOA that disproves the proposition that except in some very special cases, 3/3 is a waste of time, money, and oil that can't be objectively justified.
That ought to do it.
Oh yeah, one more thing, ask for and talk about particle counts. In clean, healthy engines, using a decent filter, the PCs will generally be very low in even 5-10k mile oil for anything above about 5 microns, which is around the tightest clearance found in a normal piston engine. Professional intperpretational (I mean Terry, of course...) of the PC numbers will demonstrate that particle accumulation, another refuge sought by those trying to rationally justify very short OCIs, also fails to support their argument.
Nope, that's fuel dillution.
The Sulfer in fuel and the water produced during combustion produce SO2 and sulfuric acid compounds which are the acids. Liquid fuel in the oil acts as a solvent and keeps the lubricant from performing optimally.
The Sulfer in fuel and the water produced during combustion produce SO2 and sulfuric acid compounds which are the acids. Liquid fuel in the oil acts as a solvent and keeps the lubricant from performing optimally.
With modern engines, even the unburned fuel/dilution issue is not the across-the-board major problem some think it is. With a healthy fuel injected engine, that has a properly functioning crankcase ventilation system, dilution isn't the problem it was with the carbureted engines of a generation ago. Sure, we occasionally see some dilution in our UOAs, but rarely is it a bad case. My wife's 4.7L Sequoia is normally not driven for more than 2-3 miles at a time (we put roughly 10k per year on it, including maybe one or two road trips). In three UOAs, (one in which the GC we used went 13 months & 10k miles), we haven't seen dilution (or water accumulation). Haven't seen any dilution in my G either, but it gets at least two long highway runs (200 mi each way) weekly, balancing out the commuting short trips. The issues Bryan raised are valid, but only if your engine is actually accumulating fuel and water in the oil. Another reason why I like to do occasional UOA.
I almost couldn't sleep last night after thinking about my post Ekpolk !
Modern fuel injected engines do not have the fuel dilution issues that carburated vehicles did.. If you ever started a car with a mechanical choke you can remember how rich they burned fuel and must have dumped alot into the crankcase. Todays engines are constantly tuning the ignition timing, and fuel injection to maintain the optimal mixture resulting in very little unburned fuel.
In the past it was possible to see the dipstick level rise with fuel dilution This is no longer common.
Modern fuel injected engines do not have the fuel dilution issues that carburated vehicles did.. If you ever started a car with a mechanical choke you can remember how rich they burned fuel and must have dumped alot into the crankcase. Todays engines are constantly tuning the ignition timing, and fuel injection to maintain the optimal mixture resulting in very little unburned fuel.
In the past it was possible to see the dipstick level rise with fuel dilution This is no longer common.
MolaKule
Staff member
And don't gorget anout the nitric acids produced by NOx generation due to combustion.
Molakule: You sure you got adequate ventilation in that lab of yours???
Seriously,
The presence, and to some extent, concentration, of nitric acids would be reflected in the TBN (or perhaps the less commonly seen for oil UOA, TAN) measurement, right? Of course, I don't mean concentration in the sense of a precise measurement, just that a TBN of 1 might suggest that there's been more acid present than a TBN of 5, for example.
MolaKule
Staff member
hehe Ek, you caught me. Anout, snort, ahem, cough!
Standard revised version:
"And don't gorget about the nitric acids produced by NOx generation due to combustion."
Basically what I was saying is that soluble elemental and decomposed sulfur, along with nitrous gases from combustion, BOTH contribute to acids in the oil.
It is the alkili components of the detergents that neutralize these acids, and as acids build, the tbn comes down.
But unless you have a loosy-goosey engine with high blow-by and run the oil past its prime, these acids are very weak and are neutralized before much harm is done.
Standard revised version:
"And don't gorget about the nitric acids produced by NOx generation due to combustion."
Basically what I was saying is that soluble elemental and decomposed sulfur, along with nitrous gases from combustion, BOTH contribute to acids in the oil.
It is the alkili components of the detergents that neutralize these acids, and as acids build, the tbn comes down.
But unless you have a loosy-goosey engine with high blow-by and run the oil past its prime, these acids are very weak and are neutralized before much harm is done.
I would like to understand the nitration process better.
Bryanccfshr,
With enough heat and enough oxygen, atmospheric nitrogen can be oxidized (burnt). This is an endothermic reaction (up hill battle).
With enough heat and enough oxygen, atmospheric nitrogen can be oxidized (burnt). This is an endothermic reaction (up hill battle).
Dead on Bryan.
I can vividly recall my parents' two Dodge Darts (a 68 and a 73) and the wonderful smells they generated as a result of the "automatic" choking of the carb. Especially in the winter (EDIT: I grew up in New Hampshire - cold cold in the winter), often after struggling to get the car started, they'd let it idle to warm up for a while. With all the excess raw unburned gas running through it, it smelled like an oil refinery disaster in progress if you got within 50 feet of the poor car. Today, I cringe at the thought of what this must have been doing to the oil.
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