How do engines die?

[vincenzo masiello]

So, my current car is the first one I had this long and that’s been aging in my possession. I’m planning on keeping it forever (or whatever practical with cars that may mean) and did replace the transmission two years ago and little by little took very good care of it at lower and lower costs while little by little becoming an expert about everything about it.

It currently has close to 150K miles. It has an indicator of “oil age” or “oil life time” that decreases with time and is manually reset back to 100% at the time of oil changes. I’ve always been using this number in addition to miles and time to make the oil change decisions.
I usually change engine oil with the best high-mileage brands every time that age gets to around 55% which most of the time makes me change oil every month (too frequent, I guess!). In the last 10-20K miles, I started loosing some oil between changes (aging, tear and wear) that may get up to 1qt loss. I have the following questions:

1.If, theoretically, I change oil every 2 months, and add a qt every week (hypothetically), doesn’t that make for more than a total oil change (disregarding the filter)?

2. If the answer to 1 is “yes” or “kinda”, then can I start increasing the time/miles between oil changes? (probably from 55% to, say, 25% of oil age)

3. Is there an upper limit for the amount of lost/burned engine oil at which some kind of diagnosis/inspection/repair has to be done? and what usually, is the repair?

4. If the answer to 3 is no, and that engines can get to a point where there won’t be any need for oil changes because oil is being ADDED continuously (only filters may be changed from time to time), then when is it a “good” time to rebuild/replace an engine?

5. I heard that replacing is better than rebuilding, and that remanufactured are the best option when it comes to the cost/quality compromise , and I tend to agree with both to some extent. How long (in KMiles) do those 3800 GM engines usually last (original and re-man’ed) for a well taken care of car?

thanks
(my car is a 2008 grand prix with all the luxury options that were available that year, and has close to 150K miles, I’m in PA, USA)

Topic

[Richard Kirshy]

1.If, theoretically, I change oil every 2 months, and add a qt every week (hypothetically), doesn’t that make for more than a total oil change (disregarding the filter)?
Yes

2. If the answer to 1 is “yes” or “kinda”, then can I start increasing the time/miles between oil changes? (probably from 55% to, say, 25% of oil age)
[color=orange]If your losing or burning that much oil you have larger issues than time or miles between oil/filter changes
[/color]
3. Is there an upper limit for the amount of lost/burned engine oil at which some kind of diagnosis/inspection/repair has to be done? and what usually, is the repair?
[color=orange]I’d say if the conditions your describing are factual, you’ve long passed the upper limits.
As to what[/color] ” diagnosis/inspection/repair has to be done?”
[color=orange]That will depend on a few things….
Is it leaking? bad seal(s) or gasket(s)
Is it burning? Bad rings, worn vale seals
[/color]

4. If the answer to 3 is no, and that engines can get to a point where there won’t be any need for oil changes because oil is being ADDED continuously (only filters may be changed from time to time), then when is it a “good” time to rebuild/replace an engine?
[color=orange]Losing or burning that amount of oil is not only bad for the environment, but could easily get you a few tickets.
When is a good time to repair / rebuild or replace the engine???? …..
According to nominal oil consumption specs, probably when you started losing more than a quart of oil in 1,000 -1,500 miles of driving.[/color]

5. I heard that replacing is better than rebuilding, and that remanufactured are the best option when it comes to the cost/quality compromise , and I tend to agree with both to some extent. How long (in KMiles) do those 3800 GM engines usually last (original and re-man’ed) for a well taken care of car?
[color=orange]One persons idea of well maintained may not be the same as another.
If you discount certain design flaws, no reason that the basic block and heads should manage 150,000 – 250,000 miles, again, this is all dependent on driving conditions, driving habits and maintenance[/color]

[vincenzo masiello]

thank you for the answers.
I never mentioned 1000-1500 miles, but i mostly get to 55% after driving 3500-5000 miles.

I don’t have any smoke out of the ordinary coming out of the exhaust to assume oil burning and i left cardboard pieces under engine overnight several times with negative “obvious” leaking clues. I don’t really care about the environment and I voted for Trumps in the last few elections, and I totally believe that my money is more important than the planet or the milky way.

what would you do if you were in my shoes?
Is there a reasonably priced diagnosis? or does it cost close to replacing? (a nice experienced mechanic gave me a price of replacing with a reman’ed engine for $2600)

[Richard Kirshy]

Given the excessive amount of oil loss
If a experienced mechanic suggested a motor replacement, he should of explained the reason(s) for that

i left cardboard pieces under engine overnight several times with negative “obvious” leaking clues
If your dealing with a bad seal or gasket, it is possible to be losing oil while driving when the oil pressure is higher.
Might try crawling under the vehicle and look for oil wet spot(s)

As to diagnosis testing, a compression test and leak down test will determine the health of the motor and localize what area(s) are lacking.

[Author]

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