Shorter OCI as engine gets older?

[The Critic]

Originally Posted By: dblshock
clean'r up, start TCW-3 oil in the fuel 640/1.


Sounds like a great way to potentially contaminate the spark plugs, oxygen sensors and catalytic converters...

 

[dblshock]

Sounds like a great way to potentially contaminate the spark plugs, oxygen sensors and catalytic converters... [/quote]

Contraire my friend.

 

[Rolla07]

They say to never judge oil by its color but there are only so many ways to think. Either change oil before it looks dirty, trust a used oil analysis or keep the same intervals as you have always done. My car has a 5k mile interval per manual. I tend to get bored and change my oil out sooner than that. At what mileage does it look "dirty"?
If it makes you sleep better just change it more often.

 

[SilverC6]

Certainly the rate of wear is less as more miles rack up on the car.

Wear does continue though or you would never wear out an automotive engine.

So a car with 200,000 miles would necessarily have more space between the rings and the cylinders than when it had 50,000 miles.

To the OP, I would shorten the OCI's down to 7,500 miles.

If for no other reason, just to monitor the engine until any change going on becomes apparent.

You can always return to 10,000 mile intervals later.

 

[artificialist]

Sometimes when an engine gets old, the fuel injectors stop spraying in a consistent pattern, resulting in unequal fuel distribution and too much liquid fuel entering the combustion chamber. Both situations would cause incomplete combustion, dirtier emissions, and more oil contaminates.

The other thing that can happen is an engine sensor that is failing, but not badly enough to create an error code. That can lead to an excessively rich mixture which would generate more emissions, and lead to more contamination of the oil.

What are the condition of your spark plugs? I have seen numerous cars state that the spark plugs are good for 100,000 miles, but actually only last 60,000 miles. If the spark plugs are weak, that also leads to dirtier combustion and more heavily contaminated oil.

How well is the piston and ring design in this engine? One engine I know of that has a bad piston and ring design is the 1991-2002 Saturn 1.9L DOHC engine. Even if you changed the oil every 3000 miles on those engines, they would still have major varnish.

 

[bluestream]

Originally Posted By: dblshock
clean'r up, start TCW-3 oil in the fuel 640/1.


Are you kidding??

 

[dblshock]

Originally Posted By: Bluestream
Originally Posted By: dblshock
clean'r up, start TCW-3 oil in the fuel 640/1.


Are you kidding??

Not at all..run it in all my engines...numerous threads on the subject.

 

[SilverC6]

Originally Posted By: dblshock
Sounds like a great way to potentially contaminate the spark plugs, oxygen sensors and catalytic converters...

Contraire my friend.



Ashless 2 cycle oil burns cleanly in the combustion process.

I believe I'm extending the seal life in my son's Mazda RX8 with a constant diet of Super Tech 2 cycle outboard oil in its fuel.

Of course that engine injects lubricating oil into the combustion process as needed.

 

[gregk24]

Originally Posted By: Clevy
Originally Posted By: gregk24
Yes, engines DO wear and will allow more blow by than when it rolled of the lot for the first time. So shortening your OCI does make since, by how much? No one could tell you. IMO 10K is to long anyway, too long if you want your engine to hit 200,000 miles or more anyway. If you want your car to go the distance, I would change it every 5k +/-.



Truly absurd.


The only vehicle I own that doesn't have 200k is my charger and I'm running 10k intervals on everything from my fleet of work vans to my personal vehicles.
How long have you been here?
Haven't you learned that wear actually DECREASES as miles rack up on oil?
Any my engines are spotless inside.

Wanna try again or are you so stuck in that way of thinking you simply aren't able to learn anything new?


What type of driving do you do?

 

[nitehawk55]

Flush her out with some MMO !!

 

[Istvan_Buda]

I'm going to change oil after every fuel fill up...better safe then sorry

 

[dblshock]

Originally Posted By: Istvan_Buda
I'm going to change oil after every fuel fill up...better safe then sorry


i'd be damedsure it's botique $6.00 a quart!

 

[Doog]

Originally Posted By: The Critic

Does anyone else practice a shorter oil change interval after a certain point?


No, I stick with the manufacturers OCI until 200k then sell or trade. None of my engines really consume much oil at 200k so I see no reason to shorten the OCI. You might want to switch to a high TBN oil or possibly a High Mileage oil. But that's about all I would do.

 

[jorton]

Next time you check your oil wipe the dip stick with a white paper towel. Look for a black mark on the paper towel. If there is one, clean all of the carbon off the dipstick. Then check every so often to see how long it takes for carbon to collect on the dip stick. If it takes only 2 weeks I would say the crank case is a little smoky. If it takes 6 months I would say that's normal.

 

[daves87rs]

With the age and the beating that my wife's car takes, I think Critic's asking a pretty fair question here.

It depends on many things, but there is nothing wrong with cutting back a little. Thanks to this site, I've nearly gotten her car to almost 7.5k on nearly purely city driving. But her car is about a week away from hitting 100k, and between the age (11 years),milage (100k) and the really rough winter we had, I'll be cutting back more to 5-6k. And the winning combo I have (Quaker State Ultimate Durability and a fram Ultra), means I might change it an extra time (maybe two), by I'm not sweating it..

One of the biggest reasons I am doing it is for a extra level of comfort. I'm not seeing her car like I used to, so if nothing else, it will get checked more often. And help combat our crazy weather here.

My wife is in no rush to get rid of it, So whatever extra care I can put it it, I will.....

 

[crazyoildude]

oils today clean better than ever so they turn black faster

 

[Kuato]

I keep the same interval. If you're concerned with oil condition, the only way is:

Originally Posted By: OneEyeJack
Oil analysis for $25.


^this.

Originally Posted By: The Critic
...

Without a baseline, the info obtained from a used oil analysis would be meaningless...unfortunately.

...


Then do more than one to establish the baseline. Until you do, it's all conjecture.

 

[MrQuackers]

I just changed the oil 3 times in one day on my 1.9 liter DOHC s-series engine. I just resealed the cam cover and thought it would be a good idea since I had the cover off. I put in Mobil 1 Turbo Diesel Truck for the final oil change. It likes it!

 

[Trav]

Originally Posted By: The Critic


And 90k is fairly high mileage

Thats what they would like people to believe so they trade in. In reality it is absolute bovine excrement a little pessimistic.

If you think it may be a little dirty just shorten the OCI for a couple of changes then back to business as usual.

 

[fdcg27]

I have a couple of thoughts.
First, if you think that your car is now halfway through its life, then why even worry about OCIs?
You could probably double your OCIs and the engine would be fine for another 90K.
Second, while you're right about industry standard durability, that applies to the car as a whole, not just the engine.
The average 200K car will be at least ten years old, and every part of it will have suffered through years of use. While it isn't a consideration where you live, here such a car might well have extensive rust damage. It will also have suffered through years of neglect in the hands of its second or third owner.
Mechanically adept folks willing to get their hands dirty can keep a car serviceable and safe well beyond 200K.
Most folks who rely upon paying others to do the work won't find this economically realistic and will scrap the car.