I have a feeling I know the answer...but...don't laugh. My last oil change was 12/15/09 at 46,391 miles. I now have 50,400. It is a 98. I didn't drive it that much. Now that I got Magnaflow 16732 muffler it is like a new car and I am driving it more. Get an oil change ...right?

 

Right! At least once a year.

 

I hope this is a joke thread, Have you ever read the manual? You are at best 3 years over due.

 

I would change it and then out of curiosity, would send a sample in to Blackstone to get it tested to see if the oil was actually even phased.

 

I would be interested to know as well.

 

Um......

 

.. Oh right... you said not to laugh!


I have a feeling it would be just fine.

 

For piece of mind I would even drop the lower oil pan if you have the two piece pan. I don't remember what years had the two piece but I know my 2000 does.
It would be interesting to see if anything has settled on the bottom.

Edit:
Here's a thread that I used.
http://forums.corvetteforum.com/c5-t...-fod-pics.html

 

Right!

 

The owner's manual states that you should change the oil at least once a year (even if you don't drive it enough to do a regular oil change due to the oil life monitor calling for one). I would certainly change it now.

 

its not that much

 

It's moisture you are trying to avoid. The oil sits water condenses on top of the oil. Oil doesn't go bad from sitting on its on. I'd drain it and start fresh. I've ran old barn finds with the oil in them just to see if the motor is sound. Squirt a little marvel mystery oil or atf in the cylinder, let it set a bit and bust the crank loose with a break over if needed and you're good to go.

 

I already know the answer to this , we did extensive studies over two years of development. The reason the OLM was coded, and we said use the Oil Life monitor because it works, or One year, what ever comes first. The reason we tell you to change the oil after one year is because when the oil is exposed to carbon and internal combustion, the DNA of the oil turns acidic. This is a very big thing and over time the acidic condition attacks all the seals in the engine. Things like valves seals and cranks seals and o rings are at risk. I had the clueless argue that its impossible to say that exactly at 1 year the oil turns acidic. The idea is the PH changes before one year but the level of acidity is not bad enough to cause any problems. but a year is a good marker for proper maintenance, to avoid problems down the road. No one wants want to be running acid through their lubricating system. this is similar to changing the water lines on your washing machine every five years to avoid problems. Even if all the heavy metals are below a dangerous level is the PH of the oil itself that is a problem. Even if a engine sees 500 miles in a year, the oil still becomes a liability. That's the reason for the change in One year recommendation. The oil life monitor was designed to save the owner money by giving them a real idea of how the oil is broken down over time, and mileage has very little to do with the integrity of the oil. We even bumped the base line up to 15,000 miles in 2000 because the Oil Life monitor worked so well. Originally it was 10,000 miles. this is where the reset starts. Over time the OLM reads the engines run characteristics against the base line and reduces its life and displays that life on the DIC. You can take the OLM down to 0 because there is still soe life left in the oild. we designed the 10 % warning as a means to let the owner know that an oil change is necessary. At this point you should make an appointment to have it changed, or go and buy oil and a filter, so that when the OLM gets to zero you can change the oil and get the most out of your oil without any cost to the engine life. remember we built this car to run to 200,000 miles. A benchmark for engine life, the LSX engine is the first North American engine designed to go 200K. Every other engine design was benched to 100K. This was a mandate brought to you by Dave Hill. The OLM is a big part of this effort.
This is just some more inside information as to why and how we designed this platform, with the owner in mind.
Bill aka ET
Bill aka ET

 

Very interesting response ET. I'm intrigued that the carbon exposure of the oil causes the PH to turn acidic. I thought oil life was a function of degradation due to exposure to the high temperatures of combustion. I guess everything is a factor in the end (metallic contamination, thermal degradation, PH transition to acidic...etc). Is the source of the carbon from the byproducts of incomplete combustion or from the carbon of the steel? Would a synthetic oil deter PH alteration as compared to a conventional oil?
Thanks for your insight.

 

I'm still hoping the OP gets the oil tested and lets us all know the results.

OP, as a suggestion, if you do this, when asked how long since the last oil change, answer "Unknown." Reason being, if the testing facility doesn't know, they then can't factor age of the oil into their evaluation. Kind of like a blind taste test. Makes them present the results solely on their chemical analysis without any undue influence from knowing how long the oil had been in the crankcase.

 

Part of the oil additive package is an acidic neutralizer (TBN ). The problem is most people do not get a TAN test because it cost 36 dollars by itself. ( TAN = Total acid number ) Blackwell and others offer this test as an option. many people use the TBN to determine how much additive is left in the package. GM did Outside testing on oil over time and spared no expense in doing this. I know most people just want to see the heavy metals numbers and the extraneous minerals. If you don't ask for and pay for a TAN you wont get it. the Blackwell standard test I believe is around 40/45 dollars.. add the TAN to it and its about 80 dollars. Most people change their oil too much, especially those who are concerned enough to have their oil analyzed. People who are lazy about their oil changes usually are tight with a dollar and would never spend 80 dollars on a proper oil analysis. The additive package ( TBN ) wears very thin after a year. That's why we tell people to change it every year. Its pretty simple insurance. I find it always funny how construction workers and city municipal water workers can determine that GM engineers don't know what they are doing and just throw out these numbers as if they pulled them out of a hat.. I also find it interesting when I see the occupations of some of the people that refute the maintenance schedule and recommendations just to save a buck and interpret these maintenance schedules any way they see fit. Like its ok to run 87 octane all the time, run your engine cold, don't use the OLM, etc. Thousands and thousands of dollars were spent in the development of this engine, yet many people are willing to listen to a maintenance man at a bank, or a retired postal worker, instead of the guys who built this car.
Now use an non- spected GM oil in your LSX engine and you wont have the High temp additive that helps to keep the oil stable at high temps found in an LSX engine. Its there for a specific purpose, to increase the flash point temperature, to reduce the chance of high temp thermal breakdown which destroys the additive package.

 

I am a real newcomer here and amazed at what I have learned already. Evil Twin your writings here re oil are incredibly insightful and helpful. Thanks a lot for taking the time to write something like this!

 

You make it sound like a 15 minute job to drop the pan...I have a small leak in my upper two piece. I believe it cost $1200- to replace pan gaskets.

 

First of all, it's Blackstone, not Blackwell, that does the testing. Secondly, the standard oil analysis costs $25 and the TBN is an extra $10, for what you said would run $80 is actually just $35. Quite a difference. Don't believe me, here's the link to Blackstone's pricing: http://www.blackstone-labs.com/tests-price-list.php

As to the specific comment "The additive package ( TBN ) wears very thin after a year. That's why we tell people to change it every year." Wear on the additive package depends on factors more important than age. More specifically, the factors that go into the calculation used in the OLM. Basically, the actual use of the oil in lubricating the internals of the motor. As an extreme example, let's say the oil sits in the oil pan for a year with no use. It would have no wear on the additive package. It would be no different than it sitting in the jug on the shelf. Does the additive package wear out sitting in the jug on the shelf? I hardly think so. So to say "The additive package ( TBN ) wears very thin after a year." is quite misleading. It's more from the actual use of the oil and less from its age that results in deterioration of the additive package. BTW ET, correct me if I'm wrong (although I'm pretty sure I'm not) but age is not one of the factors used in the OLM, is it?

 

I hope you are not talking to me... you seem to think my 30 years at GM and my two engineering degrees was wasted on flying paper airplanes in the office.. You are so quick to jump on an obvious typo...you are argumentative and have no place quoting me.. If you have an opinion and you want to express, post it to the op please do so. But don't quote me with your silly and childish typo catch as if that was important to the fact of my post. BTW I worked exclusively on the code for the OLM in 95 and finalized it in 96, Im an absolute expert on its function. I also have seven proprietary designs in every C5 on the planet.. so you keep catching my typos and Ill keep posting what I know about a C5.