@wesw You can’t tell your oil’s condition from “simple observation”. The only thing you can tell is how black it is which gives some indication of the amount of carbon, but not necessarily if the carbon is at a danger point.
The acid number or base number in an oil analysis tell you how far the oil has deteriorated from normal; too much acidity causes corrosion. Too many wear metals will not showe up to the naked eye. If you burn propane or natural gas, the oil is subject to nitriding, another contamination you can’t see.
The viscosity is hard to measure by observation; again, too viscous shows too much carbon and sludge, too thin is likely fuel contamination and dilution.
In short, if you oil looks “really bad”, you already have done damage to your engine.
Too much water will show up as foam, and make the oil coffee colored. When you reach that point you probably already have a serious problem.
As pointed out dedicated car owners use oil analysis to see if their drain interval is too long or too short. They also use it occasionnally to see if there is any damage developing in the engine, such as bearing failure. I gladly spend the $30 or so to occasionnally do so.
If you switch from dyno oil to synthetic long life (10,000 mile) oil, and go from 5,000 mile oil change intervals to 10,000 mile oil change intervals, a used oil analysis can confirm your car will last as long as it would have otherwise.
You THINK it’s addressed in that…but it isn’t. It does NOT confirm it will. That’s a false assumption. Sorry.
@MikeInNH, are you saying that if I test my synthetic oil at 10,000 miles, and the test shows the oil is in as good of shape as dyno oil at 5,000 miles, the synthetic 10,000 oil will somehow harm your engine in spite of the fact that it passes a used oil test and shows it is still usable?
Could you please explain how that logic works? How would you design the research to test this theory?
It’s one thing to shoot down my idea, but it’s another thing to propose your own solution. Anyone can stand back and criticize someone else’s idea, but it takes a thinking mind to propose a better idea.
maybe you underestimate my powers of observation. I can certainly tell more than how black it is.
I can tell if there is fuel in it. smell
I can tell if there is water in it. sight
I can tell if there is grit in it. feel
I can tell if its deteriorated. feel
I could probably test the ph with a pool test kit if I wanted, I don t
what can you really do about trace metals in your oil ?
start saving for a motor I guess…
anyway I change my oil regularly, problem solved
are you saying that if I test my synthetic oil at 10,000 miles, and the test shows the oil is in as good of shape as dyno oil at 5,000 miles, the synthetic 10,000 oil will somehow harm your engine in spite of the fact that it passes a used oil test and shows it is still usable?
Usable to what degree? That it’s 100% as effective as NEW OIL? I don’t think so. What the oil analysis is telling you is that it’s still lubricating…and that the oil is NOT going to destroy your engine any time soon. Even oil that only has 5k miles has heavy metals and other particulates smaller then 25microns (typical good filter). Over long periods those particulates can do minute damage to engine components (cylinder walls, bearings…etc). After 15k miles those particulates are 3 times more present then at 5k miles. So I stand by my statement - 15k oil change intervals (even with periodic testing) does NOT show the engine will last 300k miles.
@Whitey.
Excellent thoughts and a good idea. I like that you are willing to put your money where your mouth is. My plan is less ambitious. I plan to just start doing it. Why? I only keep a car for ten to fifteen years and my miles have dropped to about 10k per car per year. Looking forward to the results. Just remember that we are all pretty old so drive those 10k miles quickly. take a couple of long trips.
@MikeInNh.
I think we still conflating mineral oil with full synthetic oil. When you change your mineral oil and it becomes NEW at 5k miles, used synthetic oil at 5k on it’s way to 10k, DOES STILL HAVE better lubricating properties, especially related to cold start up. That is pretty easy to tell on any cold morning for me with my newer car with synthetic over my old with mineral oil and that is valuable start up wear that is saved.
After 10 k miles, synthetic oil is still suppose to have retained it’s viscosity rating as well better then mineral oil at 5k. You have said, you are changing you cars oil on one with mineral oil. Now if on the other, you change synthetic on your newer car at 5k miles, then it’s entirely different debate. Yes, your car will be better served, just like changing a mineral oil at 3k instead of 5k on your old one.
But you have already decided to go to 5k in mineral over the previous 3k in mineral. So, you are doing the same same adjustment with synthetic…just doing it with a better oil at higher intervals.
I hear you say, “I don’t think so”; well, with tests and analysis, there is little reason to just think. You will know as do the people I know do with their fleet cars.
Ok Mike. How would you design the experiment to test your theory?
I’m not sure there is a laboratory test. A good real-world test would be have a double blind test of a few thousand vehicles and run them to 300k miles. Some - the oil will be changed every 5k miles…others - every 15k miles. Then keep track engine problems as the vehicles approach 300k miles. I guess you could do this in a lab with just a handful of vehicles. But a small example might be meaningless.
These comments were made because regardless of your statements, for clarity sake, you seldom said specifically which type of oil you promoted for which interval.
Please read completely, fleet cars of people “I know” not those in your sample, which includes my state with vehicles well over 200K and uses extended intervals and uses analysis and my two neighbor businessmen who each use their vehicles till the bodies rot…including delivery vans and plow trucks…mileage: well over 150K miles and some trucks over 300K. They don’t analyze the oil.
"Typical Dag…You LOVE to interpret (WRONGLY) what other people have said. "
If you take it personally and want to get into a peeing match because you can’t take anything that even remotely seems contrary to your beliefs without getting defensive and abusive, that’s your problem. Just wear water proof shoes cause you’re on your own. Noted.
These comments were made because regardless of your statements, for clarity sake, you seldom said specifically which type of oil you promoted for which interval.
For clarity sake…this whole thread has been about synthetic. I NEVER said synthetic…but yet you made the argument that I did say regular dino oil. Re-read your own post.
Please read completely, fleet cars of people "I know" not those in your sample, which includes my state with vehicles well over 200K and uses extended intervals and uses analysis and my two neighbor businessmen who each use their vehicles till the bodies rot...including delivery vans and plow trucks.
Since you live in ME…what state agency keeps their vehicles past 150k miles. I want to know…because last year we bought 4 cars from the state of ME for use by town employees…and they all had less then 150k miles…one had less then 100k miles. No state agency in NH keeps their vehicles past 150k miles. And I know NY doesn’t either.
If you take it personally and want to get into a peeing match because you can't take anything that even remotely seems contrary to your beliefs without getting defensive and abusive, that's your problem.
No - the problem is Dag…YOU like to twist peoples words and argue about something on one else said so it looks like you’re winning the argument. MB and others have called you on it many times over the years.
@db4690, clearly it is the 5.7L since it is the only V8 on your list. I’m sure you know more about the issue. I quote from a published study. You work with these vehicles every day. And you work for California state govt., don’t you? What do you know about the study?
Close . . . I’m a fleet mechanic for a large California city
As a matter of fact, I never heard about the study, until you brought it up
But I have seen those gaskets disintegrate. For what it’s worth, the vehicles seem to be over 10 years old when it happens. What’s more, the warning signs are often quite evident for some time. Not only do they leak coolant into the crankcase, they also leak externally, and this is usually visible when you’re doing an inspection. It starts out as seepage, when coolant starts trickling down onto the ground, it’s a good bet the gasket is a complete goner
Unfortunately, the 4.3 V6 shares the same problem, because of the gasket composition. That is a heads up for any regulars reading this who have a pre-2004 GM 4.3 V6 under the hood. I said pre-2004 because starting with the 2004 model year, GM used the updated style intake gaskets on that engine.
For some reason, it seems that the older GM 7.4 V8 doesn’t suffer quite as badly. Those intake gaskets also leak, but the composition was different.
Do you really think that states set a limit on all their vehicles at some arbitrary 150k mile limit ?
Some Marine patrol car use, administrative and detective division and other agencies that are not number one priority for hard use vehicles ( including high idle time) in our state use trucks and cars that have been transferred from regular use. Sometimes cars are also shifted to legislative use and still get plenty of miles put on them well past the 150k. Even the state DEP could get a vehicle car or truck, rotated to them. Their plow trucks and heavy duty work vehicles may be kept well past that mark and NONE are routinely sent out to pasture on some arbitrary 150k schedule. The department of transportation gets new vehicles every 150k ?
Please read some of your own posts where you continually refer to different oil change limits and never mention which type of oil. And no, this whole thread has not been about synthetic oil only. Read other posts by others in this thread you can see that. Read Whitey’s opening comments that include the remark referring to both regular and synthetic oil being part of the discussion. So no, this whole thread has not automatically been about synthetic oil.
Lastly. Your abusive words speak for itself. You may hide behind that fact but even MB with whom I am on totally opposite ends of the political spectrum is more cordial then you with your comment.
The intake gaskets on the 3.4 are apparently not as bad as on the 4.3 and 5.7. The rubber sealing part of the gasket often splits after years of use, but the gaskets don’t literally disintegrate, as on those other ones. From what I can tell, at this point
Here’s what happens on the 3.4. The 3.1 is very similar
Do you really think that states set a limit on all their vehicles at some arbitrary 150k mile limit ?
Never said it was arbitrary. 150k limit (or less) is very common. I suggest you do some research. Look at fleet vehicle auctions. I see very very few anywhere near 200k miles as you claim. Let alone approaching 300k miles which I’ve CLEARLY STATED MANY TIMES is the number I keep my vehicles.
Please read some of your own posts where you continually refer to different oil change limits and never mention which type of oil.
Since this whole thread has been about extended oil changes with Synthetic oil…why do I have to mention what type of oil.
take a couple of long trips.