30 yrs ago the oil was not as good as today, machining tolerances were worse, and oil filter technology has come a long way

 

I am going to AutoX for the first time tomorrow. My oil has about 3,000 miles on it now and is at the level it should be. Should I add a half qt. - 1qt. and then change it afterwards...?

 

I don't know about that....listening to my DIC used to get me into all kinds of trouble.

It may be unnecessary but I change my oil when the indicator shows around 60% oil life remaining. IMO fresh clean motor oil is always preferable to older, dirtier motor oil.

 

Personally, for track events, I always ensure my car has fresh oil.

 

To change the oil before the DIC indicates is illogical.

 

Every 3 MONTHS or 3000 MILES, here. Oil is cheap, engines aren't.

 

Can one person here show me oil analysis data at 3000 that shows the oil is "bad" and should have been replaced?


Your car, your money, yeah yeah.

What a foolish waste.

 

Mobil 1 Test Results
http://neptune.spacebears.com/cars/stories/mobil1.html

"what have we learned so far? Here are a few points to ponder, based on our experience with the Mobil 1 phase.


Getting just one oil analysis only tells a tiny piece of the picture. It essentially would serve only as a pass/fail mechanism; without a trend to monitor, the most interesting parts of the analysis would be impossible to see.
Total base number is a moving target. There are multiple methods for testing it, which makes comparisons between laboratories worthless, and none of the methods have repeatability rates worth getting excited about. While TBN is worth considering as part of the larger picture, as a singular measure it is too flawed to rely on.
Engine wear actually decreases as oil ages. This has also been substantiated in testing conducted by Ford Motor Co. and ConocoPhillips, and reported in SAE Technical Paper 2003-01-3119. What this means is that compulsive oil changers are actually causing more engine wear than the people who let their engine's oil get some age on it.
Topping up the crankcase is a critical component of extended oil change intervals, and frequent filter changes are most likely the key to extreme-length intervals. The cumulative effect of even minor top-ups, let alone a filter change, substantially increases the longevity of the oil.
Based on the results we've got here, we'd recommend 8,000 miles between oil changes on an engine that uses no oil at all, perhaps 10,000 miles on an engine that uses some oil, and 15,000 miles or beyond with a filter change every 5,000 miles. This, of course, isn't any kind of guarantee, and you must evaluate for yourself what your engine requires. One thing we're pretty sure about though: 3,000-mile intervals is a huge waste of resources."


GM Oil Life System & Simplified Maintenance
Frequently Asked Questions
http://www.gm.com/company/gmability/...qa_040104.html



GM Engineer States that Oil Change Intervals Average 8,500 Miles with Oil Life Monitors...........

http://www.performancemotoroil.com/G..._Monitors.html

Typical drain intervals with General Motors’ Oil Life System, the onboard computer algorithm that tells drivers when it’s time to change their motor oil, are 8,500 miles, versus 5,000 for GM’s competitors, a GM executive told last week’s World Tribology Congress. Drain intervals over 30,000 miles are achievable with minor engine modifications and appropriate oil quality.

“We cannot say exactly when it will happen, but drain intervals will be lengthened,” James A. Spearot, director of GM’s Chemical & Environmental Sciences Laboratory in Warren, Mich



Personal test done by a BMW owner with data sheet...

How often do you change your oil? Maybe too often... | ted serbinski
http://tedserbinski.com/2006/04/03/h...aybe_too_often


NY Taxi experiment........

Consumer Reports Article
The surprising truth about motor oils
July 1996, pp 10-13
http://www.xs11.com/stories/croil96.htm


Corvette forum member gets analysis done...

http://forums.corvetteforum.com/show...l+life+monitor

 

Use the DIC...it is based in sound science.

You will hear things like "cheap insurance," or doesn't cost that much, or I have always done it this way...This is all emotion. No problem with that, but if you are looking for an informed opinion, default to science, not others emotions.....

Use synthetic, start thinking about the change at 15% left, and always recycle your used oil....

 

Ok, I brought it up in an earlier in this thread, now I will flat out ask:

Who here goes by the DIC, has a modified engine (heads, cam, blower, turbo, etc.), and races their car...?

 

Modified heavily is another story.

But I would love to see oil analysis data on such an engine sometime and see if it is drastically for worse shape then the DIC would say.

A basically stock car I am sure the DIC will still give you good data on when to change even when racing occasionally.

The equations will just adjust for the greater heat, RPMS, etc.

And the manual does indeed say to add an extra quart for race day, and drain afterwards. That is going to refresh that oil a bit.

 

My point is that everyone in this thread who is so quick to speak up that - ''If you change your oil any sooner than the 7,500 mile or 15,000 miles, or what ever the hell intervals the DIC says, you are crazy and wasting money'' - all probably have bone stock cars, that are never raced. I'm even going to go as far as guessing that they have probably never owned heavily modified cars in the past, or been involved in any kind of motorsports - period.

This is just a guess. Anyone in this thread care to prove me wrong? Because you never see professional drag racers, Nascar racers, WRC racers, F1 racers, etc., etc., etc. changing their synthetic oil until 15k, right? Guess it's just emotional...

If you are going to just buy a Corvette, or any performance car for that matter, to just cruise around in then do whatever you feel like I guess... it's your money, it's your car. I just hope I don't run into one on the used car market one day.

 

ok...if you have 60% of your cold beer left do you pour it out for new fresh clean beer?



unfortunately alot of you C6 guys may not be familiar with a forum member we used to have here Evil Twin..anyway the guy was part of the team who designed the oil life monitor system....you guys who refuse to accept the facts that the DIC knows best are one of the reasons he left this forum. He tried in vain to convince members here of certain FACTS about these cars and people would argue with him...argue with a guy who actually helped design and build the very car they are driving. He was not the most tactful person and often lost his cool with people and eventually decided to just leave the forum. So all of you who know whats best for your cars despite what millions of dollars of research has proven can continue to throw away your money in the belief you are actually making a difference. The fact is most of you won't own the car long enough to ever know. I venture to say over half of you don't keep your cars more than a few years.

I agree with the guys who talk about more frequent changes for heavily modified cars as my 99 is supercharged and cammed but I still go by the DIC and ya know what....it barely gets more than about 4K before it hits 10%....I have NEVER saw oil life go more than 5K even before mods....when Mike Norris opened my car up a couple years ago to do the cam he remarked how it looked great..no signs of anything abnormal....strangely enough I change my oil by the DIC...

well now my 99 has about 80K on it still runs great....no oil related issues and still listen to my DIC

 

Not sure what your point is about NASCAR, F1 racers, how do they have anything to do with a Corvette and when to change the oil? Just doing heads, cam, and headers probably will not affect the oil life. Getting on it does and goes into the algorithm that GM developed. Some people get 15,000 mile intervals going by the DIC. Heck, I only got 5500 miles on my last oil change going by the DIC. I guess I must drive my car a little harder and live in a hotter climate.

Given that, I see you have a twin turbo setup. That is a different animal, I would not use the DIC for your car. The turbos are hard on the oil because of soak back. I liked some of the European cars that kept the oil flowing through the turbo after shutdown it eliminated soakback.

 

All those guys are race only engines. that is a total different animal agreed? Not an engine designed to last decades and be driven on the street. But to win a race, sometimes just ONCE before a total rebuild.


We are talking C6 Corvette engines here.

As for used car market, if they changed the oil when the DIC said I would be overjoyed! lots of jokers out there would probably just hit reset.

 

We are talking stock or lightly modded cars turbo_tom, don't blow a gasket. We figured you would have gotten that point...

Don't assume to know anything about anybody here, it is unbecomming of you....I've been working on and racing cars since I was 12, sorry to burst your bubble....I will say I was a frequent oil changer years ago, before engineering school...after engineering school I can say that change intervals other than what is indicated on the DIC are just a response to emotions....

I do not track or drag this car, I have no time anymore...but I will put 14 to 20 k a year on it, enjoying it in other ways....the hours of stop and go traffic is probably similar to most track conditions anyway....

 

Most "experts" I've read say the filter should be changed every 12 months or 5000 miles. IF you're going to do that, why not change the oil as well. If you don't follow that train of thought, the oil monitor is a good benchmark, imo. I kind of compromise and change at 5000 miles, which is probably going to go over the 12 months by a bit. The bottom line remains: it's YOUR car, do what you think is best.

 

when was the last post of someone who had to replace their engine? just wondering.

 

It's an old myth that the heavier the oill weight the greater the protection. Most all of us are starting and stopping many times in our daily useage of the car. It's the initial start up that in most cases that causes the most wear especially in the piston rings. The lower viscosity ( multi viscosity ) in synthetic form will give almost instataneous lubrication. The heavy weight oils take time to flow and even when they do they flow slower.

 

Tom,
I do understand your point. While my motor is basically stock (by class rules), I do have a modified PCM running the car very lean on race fuel, my cats and mufflers are gone, and the engine lives at 4500+ rpm... and I don't follow my OLM. My oil changes come out to about every 500 miles in my track only car. Your use is somewhere between mine and the average daily driver.

My suggestion, if you haven't done so already, is submit your oil to Blackstone and see how its holding up at the intervals you are currently using. You may find you can go longer, and you'll likely learn a lot about the health of your modded engine.