I just purchased my 2008 EX V6 and I would normally change the oil every 3000 miles but this new car has an oil life monitor. I am told that it is not simply related to the amount of miles you drive, so how does it work? I am not so sure I should wait until it says the oil has 10% life left in it before I change it. How does it work and are those of you who have it using it?

 

From my understanding, it keeps track of all the detailed things that affect oil life (it doesn't actually measure the oil physically or chemically). For example it counts total engine revolutions, and even the revolutions can be weighted by temperature, throttle, etc. Counts how many times you start the engine, at what temperatures, etc.

So it knows if you spend thousands of miles pounding down the interstate at a constant 65mph(!) it would probably say the oil is barely being used up. As opposed to constant autocrossing or road-course fun or ???

Really, the road miles is a poor approximation of oil life. You could say your oil life is really 300,000 "normal" revolutions of your engine; but how could keep track of that? Then you could say that every time you start the engine, add 1,000 extra revolutions to the count. Every time you start the engine below 35F it counts another extra 1,000 revolutions. Every revolution the engine turns at WOT is worth double? You couldn't possibly keep that kind of diary as you drive your car. But the ECU can easily keep track of it (school-kids can write that kind of software).

Now for real-life... My 2007 Civics have the oil-life monitor. One daughter drives real short miles from her slum-apartment into campus. Other daughter drive more miles, and longer trips. The oil monitors take that into account & call for more frequent oil-changes when the car is driven short trips. I've had an oil-sample analyzed when the monitor said 10% - Blackstone said I could've gone awhile longer on the oil. So I'm inclined to trust that calculation. It seems conservative for Castrol GTX 5w-20. If you were using some no-name $0.99/qt oil, you might want to change before the monitor gets down that low.

Check out this thread about the oil-life monitor.
https://www.hondaaccordforum.com/for...ad.php?t=27186

 

My niece has a 2010 Accord V6 coupe. It seems to be consuming oil. I added a quart to it at 4,000 miles, and it still wasn't at the full mark. I've seen some people say they get to 7-8,000 miles before the Maint. Minder said 10%. So I'm thinking she could have run very low on oil, before the car told here to change it. I wonder if it's happened to some new Accord owners? My 03 V6 owner's manual had 3.750 miles for the severe interval. People with the same engine in an 06 V6, with the MM, are going twice that far or more. Something has to be off here. I'd hate to see what my oil looks like after 8,000 miles. It would probably look like crude.

 

Losing oil inventory is a completely different thing from oil quality. You should NEVER go that long without checking the oil level on the dipstick.

Viscosity, lubricating ability (film strength) & acid/base balance are a couple things that matter for oil "wearing out". Don't confuse that with losing oil through leaks or burning.

 

The way I have always been thought (by old timers) is when you check you dip stick run the stick between your pointer finger and thumb to get some oil on them. Then press your finger together firmly and move apart. You will notice the oil will string itself from thumb to pointer finger. The father you can move your fingers apart without breaking the oil string the better the life of the oil. Now if you can't get your oil to make that string between your 2 fingers then it's past time to change your oil. I hope that makes sense cus I can't think out any other way to describe this...lol

Even know I don't really go by this and still change my oil every 3k just b/c I'm over 200k

 

Thanks Jim and others. It is really good to hear that you did that test on your oil and it was confirmed that the % left shown by the Honda monitor is more conservative than the test showed. I plan on running Pennzoil conventional motor oil as it was what took my '93 to nearly 300K and it is still running.

Jim, I am also a little nervous about running 20W in the car so I was planning on putting 5W-30 in it. I don't think that should cause any problems and probably add a little protection. What do you think?

Looks like you answered this question in the thread you attached already....

 

I think typically viscosity will reduce as the oil ages, so a 5w-30 will begin moving towards a 5w-20 anyway. That's not to say it'll last LONGER, because there's still wear-metals, & pH balance to worry about (separate from viscosity breakdown).

Probably a real big part of the oil's life is how the TBN degrades. So that should happen regardless of the viscosity. Blowby of combustion products get into the oil & lower the pH.

Why are you nervous about 5w-20? I take it you're not talking about the 1993 car in your signature? That one probably isn't supposed to take 5w-20. But a 2003+ car should be OK.

 

But wouldn't a 5W-20 move towards a 5W-10 in the same fashion?

As far as I know, the only reason Honda now specifies 5W-20 in most of their engines after 1998 is for fuel economy and making the number look better. My engine says 5W-30 on the oil cap and even though Honda now tells me to use 5W-20, I'm sticking to what was originally specified. As far as using 5W-30 instead the oil cap that says 5W-20, I don't think you would be causing any detrimental harm to engine. I don't believe the oiling system or bearing clearances were designed around a 5W-20 oil and a 5W-30 should work just fine. The biggest player here is using a quality oil and checking the dipstick to make sure it's full. Also, a functioning PCV system will keep the oil fresher, longer. At school, we've seen first hand how fast blowby and combustion gases can foul and sludge oil because of a clogged PCV valve or hose.

 

Yeah, I guess 5w-30 thinning out into a 5w-20 was a silly thing. Fouling the oil & using up the TBN would happen anyway.

One interesting thing about hydrodynamic bearings... Once there's oil pressure & the shaft is spinning, the load it can handle doesn't depend on viscosity. Only the drag force depends on viscosity. In operation the shaft doesn't touch the journals, it rides on a film of oil. Only during the first few seconds of startup should the metal wear. Lower viscosity would get moving faster & minimize the duration of that wear.

It's not a real simple situation of "thicker is better".

 

Hi Jim,

Thank you very much for all your informative posts. You bring up an interesting point about the lubrication during the first few seconds of startup.

I am wondering for instance why in a Honda engine calling for 5WXX we shouldn't use 0WXX instead, better flow at cold, quicker lubrication. the only thing is that I assume 0WXX woudl have different additive packages thn 5WXX, which may or may not be actually better overall.