Vet

So now that my 2.5 year old daughter has been keeping me quite busy and I'm forced to drive our baby-friendly vehicles 90% of the time, my poor C6 has been collecting cobwebs. Oh well, just temporary.

Recently I looked at my records and noticed that I hadn't changed the oil in my C6 in 20 months! (Yeah, that's what happens when you have kids, you lose all sense of time, and you're always behind on everything) I then noticed that I only had about 900 miles on that oil. Oil life monitor read 88%. Mobil 1, 5W-30.

As we all know, GM recommends changing the oil at no greater than 12 month intervals, regardless of what the oil life monitor says. There has been much discussion about whether or not we need to fully pay attention to this 12 month interval, some feel it's ok to run the oil longer, others feel that acids may build up over time and can be dangerous to the bearings, etc.

So I figured i'd send a sample of my 900 mile, 20 month old Mobil 1 oil in to Blackstone Labs. I ordered a standard oil analysis, plus TBN test. The TBN test checks to see how much oil "additive" is left in the oil and is an indicator of oil life. Mobil 1 5W-30 has a base TBN of about 9.8. (For more info about the TBN test, visit Blackstone's website.)

Here are Blackstone's comments on my oil analysis report:

".... Leaving this oil in place for nearly two years was fine. The TBN was strong at 7.1 (verses about 9.8 when new) so the oil still had plenty of active additive left in it. We consider a TBN of 1.0 to be too low. No fuel, coolant or moisture was found and the viscosity of the oil stayed normal.... we think this oil could have been run longer..."

All other aspects of the oil analysis were fine except for slightly high copper, but the copper in this engine has always been a little "high" since day one (I have done a few other oil tests in the past), even with frequent oil changes, etc. Not sure exactly what that's about, but at least the copper content is going down with each oil change. I've seen oil analysis reports of other C6 Vettes and they also had "elevated" copper, so.... perhaps just normal for these engines.

So, in sum, this oil analysis suggests that leaving the oil in the crankcase for 20 months is fine... at least with "fully synthetic" Mobil 1 oil with under 1000 miles of use.

BUT If the mileage had been greater, there perhaps would have been more fuel and more contaminates in general in the oil, and thus the oil may have become more acidic etc, and thus possibly harmful to the engine after the 12 month period (my general speculation).

Also keep in mind, I take VERY good care of my oil. I NEVER start my engine without FULLY warming it up. I NEVER take short trips (always long ones), and I NEVER start the engine in the winter and let the engine idle in the garage (as some people do in hopes of charging the battery etc)... in the winter, I make sure to DRIVE the car, take it on 30+ mile rides minimum, at least once a month... no idling. So, in this way, I put very little, if any, condensation / contaminates into the oil.

So for all you garage queens out there that barely drive your cars 1000 miles per year, IF you take care of your oil (like I do), I think it's safe to say that you can go at least 20 months between oil changes with no fear of engine / bearing damage. Per Blackstone's report and comments, you could probably even go a full two years with zero issues.

For those who will question why I'd be interested in extending my oil change time interval, it's certainly not in the name of saving money, but a matter of saving time. These days, with the young one puttering about, I must avoid every extra task / chore possible... just no time. Changing oil on a car when it's completely unnecessary is to be avoided. If I had more time, I'd have no problem changing the oil every 12 months religiously.

This is the first time in my life that I've put so few miles on any vehicle in a 20 month period... even motorcycles... I'm ashamed... very much against my mantra... but, it's a whole new experience having kids! The child takes full priority, everything else gets nearly forgotten about... even oil changes!

AORoads

Why you be laffin' at me, Daddy! That's really pretty darned good info, my man. This makes me feel good about not only the schedule but the oil itself (flak suit on).

Of course, you realize for the truly addicted, it will be ignored and oil will be changed every other time the car gets started.....

VETFEVER

I hear ya' bout the kids - so many cruises I have missed - but so many great moments at home

jimmie jam

well, well, well. i went through this same thing about two weeks ago. my 07 with 5,100 miles was due for it's annual oil change and i'm thinking that this is such a waist of oil. the dic says 87% life left and the dipstick oil is CLEAN. i put about 1,200 miles on it last year and was going to say NO but i did it anyway. WRONG. i knew that my driving was limited but always up to temp and no "short trip" runs. next year will be another story, for sure......

so now i don't feel that bad about my Avey that was dirven less than 1,000 miles since my last oil change 26 months ago. the dic still says 76% left. again, i rarely drive this vehicle but when i do it is a extended drive. MAYBE i'll do that one in a few months - MAYBE......

thanks for this post, perfect timing. only off by two weeks for me

KX

""Also keep in mind, I take VERY good care of my oil. I NEVER start my engine without FULLY warming it up. I NEVER take short trips (always long ones), and I NEVER start the engine in the winter and let the engine idle in the garage (as some people do in hopes of charging the battery etc)... in the winter, I make sure to DRIVE the car, take it on 30+ mile rides minimum, at least once a month... no idling."""

Each to his own paranoia, but how do "you warm up your motor without starting it"??? Some folks on here just go plain overboard as if their motors are made of some precious metal! Nothing personal guys, but hey: I had my first ZR-1 for like 17 years and that option alone on a C4 was $25,000! Nobody on the ZR-1 registry pampered those extremely costly motors but some of you guys fret like a pregnant nun over a run of the mill LS2 or LS3. Holy crap guys, GM makes them by the millions....they do not melt, it is okay to leave them alone, outside, and without an armed guard! Oh, and, it is okay to drive them to the grocery store now and then.....but watch out for the oil police....!!!!!

LMB-C6

Good info. I'm not surprised that the viscosity and additive package was still in tact - the oil only has 900 miles. It's good to hear that time didn't seem to affect anything too. Now I won't feel guilty if I go 366 days between oil changes

Patman

I've been saying for a long time now that cars that are driven less than 3000 miles per year can easily go two years between changes, and I too proved that with oil analysis reports on my mom's old 2001 VW Golf. She drove it less than 4k a year, and that car needed synthetic oil so I felt it a waste to dump perfectly good oil after such a short time, so I immediately started doing two year intervals with that car. I had two oil analysis reports done, both of them around 7500 miles worth of driving and each interval was two years. Those reports also proved that what I was doing was totally safe. My sister now owns that car (mom passed away last year) and the oil in there now has over two years on it. It burns so much oil now (those darn 2.0 engines eventually do!) that I am not even bothering to change the oil anymore, but I just changed the oil filter on it (and the oil filter even says right on it that it's safe for a 2 year or 30,000 km interval!).

So to sum it up, unless your C6 is under warranty, you really don't need to change the oil just because it has hit the one year mark. My rule of thumb would be wait for the oil life monitor to hit zero, or the two year mark, whichever comes first.

ATC399

Ok the oil is still usable..Now for the true GQs what about the hoses/belts..etc

Gearhead Jim

How many miles on your car? Our 2009 is also showing very high copper after 14k miles, and I've seen other Blackstone reports that were even worse than ours.

Vet

Howdy Jim... engine has about 17k miles on it, copper was 197 at 3k miles (2k miles on oil), was 140 at 14k miles (4k miles on oil), and is now 77 (900 miles on oil).

Now thinking about it, if I had put more miles on this last sample, my copper figure likely would have been higher. It makes sense that the degree of wear metals etc found in the oil will be a function of miles.

I found one other old report from another member, he had a whopping 8k miles on his oil, his copper was 304 (which is almost exactly double of what my copper number was when I had almost exactly half the amount of miles on the oil sample).

Vet

Howdy Bill, thanks!

cylon

I read this and had to go out and chnage my oil....just for all those who forget

AORoads

that's a good one.

As to Kx's question, I believe our man Vet means when he says he never starts the car without warming up the oil---if he starts the car, he takes a long trip in it so the oil is up to full operating temp and all the moisture is boiled out.

RicK T

Interesting. Appreciate you sharing the info.

Vet

?

What I meant was, whenever I start my car, I always drive it long enough to fully warm up the engine. This allows the condensation and possible fuel contamination (which occur during start-up / cold operation) to burn off, as opposed to having it remain in the oil.

If you start and run your engine on a cold day for only 5-minutes, will your engine be destroyed? No. Will it make any difference whatsoever in the grand scheme of things? No. But is taking care of oil a good long-term habit, in general, for those who own a lot of cars and do a lot of driving? Yes.

Many of the cars I've purchased in my lifetime had been sold with over 200k miles on them, still running like new, zero sludge in the crankcase, valvetrain in perfect condition, no ticking lifters, etc. I guess you can call it a silly hobby... I get a thrill when people get in one of my cars and they say, "wow, this car is ten years old, it looks and runs like new, how do ya do it?", and then I get to say, "well, it ONLY has 200,000 miles on it, it's barely broken in!".

And I actually drive pretty hard, I'm no sissy behind the wheel... but, there's "driving hard, carefully and thoughtfully", and then there's "flat out abuse and neglect"... big difference between the two. And perhaps somewhere in-between is what most sane people do... and after a few years they trade their cars in and none of this matters.



EDIT:

Just saw this... YES!.... thanks Bill!

Vet

Thanks to all for the kind words! Glad I was able to do something useful with my 20-month old oil!

beaversstonehaven

Thanks for the excellent write up Vet. It is extreamly unlikely that I am going to have this issue as my '06 coupe has just rolled over the 100,000 mile mark. I don't know what happened.....it did not seem like I was driving it THAT much. Again, excellent write up!

Patman

What he probably meant was that he never starts his engine unless he's going to take it for a drive and fully warm it up before shutting it down. A lot of people think it's a good idea to idle their engine periodically if they aren't going to drive it, but that usually won't get the oil hot enough to get rid of the moisture in it.

Also, the copper comes from the cam bearings and it's always high on brand new LSx engines and will settle down once you get past 30 or 40k. It's nothing to worry about, the extra copper in there doesn't cause the engine to wear out sooner, it's not abrasive.

Vet

Howdy Patman! Excellent info!

Ahhh, so it's the cam bearings. Good to know it's not a "problem".

Thanks!

ejbrace

interesting thread . Thanks for posting