Back in mid September, I purchased a 2005, Z51 with only 23,500 miles on it. Since then, just last week, It has since flipped over to the 24k mileage. The lady for whom I bought the vette from was her husbands, who passed away this pass July. Of course, he only drove it on a limited bases, too, giving the year and mileage, but here is my Q. I am not sure when he last time he had the oil changed, but when I check the oil life % in the DIC, it displays 73% oil life remaining. The vette sat, undriven, for about 4 months or 6 months before he passed in July.

So, my Q is, how long can I go, before I have to change the oil? I know most rules say change it every 3k miles or ever 3 months or so, but since I only drive it maybe twice a week and less than 20 miles, when do I really need to chane the oil?

 

Change it when the oil life monitor gets to 0% or one year, whichever comes firsts. IMO, 2 years is not a stretch if it's not driven very much.
3K or 3 months is old school thinking (way old) and does not apply when using synthetic oil.
Read the owners manual.

 

 

So sitting 4-6 months prior to July would make the current oil in the crankcase now a minimum of about 10 months old, perhaps older. For the few dollars it costs to do an oil/filter change, why don't you just do it now and then you know when to change it next.

 

No manufacturer is recommending 3K oil changes any more, and I've never heard anybody recommend oil changes every 3 months.

The usual suggestion is change the oil annually if you don't put enough miles on it. Who knows what peer-reviewed study actually backs that up, but oil is sufficiently cheap that you might as well.

 

Personally - I change oil every year.

If you look at the Mobil 1 Website - they give you a mileage AND a time that the oil should be changed. The time they state is yearly. Maybe that timeframe is a gimmick to sell more oil - or possibly their engineers know stuff that we don't.

https://www.mobil.com/english-us/pas...ed-performance

Sure - some people say that you can go much longer than that. Maybe that's correct, but I believe that oil does start to deteriorate after a year.

But ... the cost for a 5 qt jug of Mobil 1 is less than $30 and let's say another $10 for an oil filter. So - we're not really talking about a whole lot of money here. I'd be willing to make a bet that you're paying a LOT more a year for insurance on your Corvette. The cost for the yearly oil change can easily be viewed as "insurance". So - it's your choice - but I have yet to see anyone say that you are hurting anything by changing your oil yearly. Worst case - you're spending money that you don't have to.... Some people I know say that exact thing about having more cars in a household than drivers.....

 

once a year is ok,but id do it every fall before putting away for its winter nap,

 

You don't know for sure when the oil & filter were changed last & you don't know for sure when the oil monitor was reset, so.....be on the safe side & do an oil & filter change now. That way you will be sure of your start point for the future. On that point, 3k oil changes are old, old school. With synthetic oils, 10K is recommended by most manufacturers & 8k is a nice conservative number that I use. Also, I would never let the DIC reading go to '0', especially driven as little as you say you do.....at a minimum I would recommend once a year. Finally, you need to put some miles on your Vette.....20 miles once or twice a week isn't enough to warm the oil & other fluids; recharge the battery; etc. Also, if you drive it so little, best to invest in a battery tender to keep the battery up to full charge.

 

Once a year, or when OLM gets down close to 0 (10% or less generally)

Mobile One full sythetic oil, and a high quality filter (OE AC-Delco at minimum, I prefer Wix Gold. Mobile One filters are also fairly good).

 

November looks like quick lube at my shop when I park my cars for winter. Not a good idea to let the acids an contaminates to sit there for a couple months without running.

 

Apparently you're not old enough to remember when the standard was 3K miles or 3 months, whichever comes first. Before that, oil changes were done every 500 to 2,000 miles. Switching between Winter and Summer grades was also SOP. It was before full-flow filters and detergent oil. Not all cars had oil filters either. Neither of dad's '33 Dodge, '41 Chevy, had oil filters. The '49 Pontiac and '53 Pontiac had partial flow filters as well as the '57 Chevy. Full-flow filters were on some cars with cartridge filters in the early '50's. Spin-on filters didn't hit the scene until the late '50's and some makes, including Chevy, only offered filters of any kind as extra cost options into the '60's.

Oil changes cars on without filters always required non-detergent oil that allowed sludge to settle in the pan. If the sludge blocked the drain, it was time to pull the pan and clean it. Lots of people would add a quart or two of kerosene and run the engine for a few minutes before draining to flush out sludge, especially on overhead valve engines.

Lots of those old practices are long outdated, yet still in the minds of current owners. Oils, filters, engines, and methods have made massive improvements since WWII. The OLM has obsoleted the odometer in determining oil change intervals, just like digital electronics obsoleted distributors, and tube type radios.

I'd be happy to do free labor for the annual oil changes on 3 cars each year that showed over 70% on the OLM, if their previous fill was Mobil 1 5W-30. I'd never need to buy oil again.

 

I posed this question to a well-known CF vendor performance shop (who will remain nameless to prevent harassment) and his response to me was "motor oil doesn't have a sell by date".
Meaning that engine use/mileage is more important than calendar dates.

 

Most new motor oil comes in sealed containers. I would not expect much oxidation / degradation in the sealed container. However - once it goes into the oil pan - that is NOT a sealed system.

Somewhere I did read that some motor oil producers were saying to use their product within 5 years of purchase.

No question - there are lots of opinions on this (and many other topics) - and most people posting replies are probably not going to change their opinion based on another post on this site. The OP asked for opinions - and a number of people have responded. THAT'S GREAT !!!! That is what a free country in all about - people having differing opinions and having the right to speak their peace! Now - the OP can look at the replies that were posted and decide what he or she wants to do !!!!

 

I'm looking at a 1964 Corvette owner's manual that recommends oil filter changes every 6 months, and oil changes every 60 days or 6,000 miles. That ratio of time to distance is interesting. The time interval seems quite short but the mileage is surprisingly long.

 

My 1941 Oldsmobile owner's manual states oil changes should be done every 1,000 miles or more often in dusty areas or if the car is mostly city driven with stop and go traffic. There is no time interval, just miles. The oil should be 20 weight unless the temperatures are over 90 F, then use 30 weight. For Winter use 10 weight and add up to 10% kerosene if expected temps are below -10 F.

So between the auto companies recommendations to protect their product and the oil companies wanting greater sales, there is an incentive by both to recommend short intervals of both time and distance. You can bet there is a good safety factor built into the OLM too.

 

The computer will reset after one year.

Also resets at mileage....you get a dash message in both cases.

If the oil life monitor was not reset one year ago, it will reset quicker.

You call, spend $75 now and get a base line so you get back on your schedule or wait till computer notifies you.

FWIW, I would do the change now and get my base timeline. Inexpensive, easy to do DIY project.

 

What are you talking about when you mention computer resetting and dash messages?

 

I was just going to ask the same thing. I can say for a fact that the OLM does not "reset" after a year. Nothing about it is based on time.

 

On the 2005 (and the C6's before 2010 or 2011), the OLM definitely is based only on engine running parameters, not on calendar time. Those vehicles need an oil change at 12 months, regardless of the "oil life remaining" shown on the DIC.

I think the OLMS may have changed in 2011 (or maybe 2010). I know I've observed a 2012 that seems to act just like the C7's, where the oil life remaining goes down by ~8% every month, even if the thing isn't driven. I've had others tell me that no C6 behaves that way, but I have direct knowledge and observation of at least one 2012 model that does that. I can't say for sure whether it came from the factory that way, or if it picked up that behavior on a firmware upgrade to the PCM (reflash). I do know for a fact that it behaves like the C7's, where the OLM shows the remaining oil life going down over time, and reaching 0% in a year.

 

Mine is Super-Charged and not a daily driver so I change it twice a year or every 1200-1500 miles. I have been and a drag racer for many years and understand the need to keep fresh oil in a Hi-Performance engine that you run hard. If it was mostly stock and my daily driver I would change it like my daily drivers every 4,000 miles. A good way to keep check on your engine even a daily driver is after you come back from driving pull your dip stick out and hold it up to the sun and look for very small pieces of silver or gold . If you see none you know your engine is not eating itself up. PS If I brought a daily driver that had been sitting over a month I would change the oil.