I have a 2008 Toyota RAV4, which holds (I believe) just above 4 quarts of oil. I do a lot of driving for work, and put 25 - 30K miles a year on the car. It currently has about 175K.
It burns oil, at a rate of about a quart a week, which I replace regularly. Given how often I’m adding new oil, how frequently do I need to have my oil changed? Manual and dealer say every 5K miles. Is there any general consensus on the “math” behind this question?–e.g., “change your oil every 5,000 + (500 * [number of added quarts]) miles.” Or is it still every 5,000 miles, no change resulting from the fact that I’m introducing clean oil into the car at a rate of about a quarter its capacity every week?
I’m not a car guy, but it seems to me that I should get some extra miles between changes. Is there a generally accepted rule of thumb known to you motorheads out there? Thanks in advance.
Rather than worrying about frequency of oil changes figure out why you are burning or leaking oil at a rate of a quart in under a thousand miles. You must be either leaving a trail of blue smoke behind you, or puddle of oil on the pavement. Whichever one it is, it should probably be fixed.
If you are burning or leaking oil then the remaining oil continues to get dirty with use. I don’t think you need to change your oil every 5,000 unless you are driving on dirt roads. My Toyota dealer said that for normal around town and freeway driving changing your oil every 10,000 miles is more than adequate. YMMV.
I have been told it is going out my tailpipe as smoke, not leaking. If I recall correctly, something about the pistons (or rings or valves or something–sorry, I’m not a car guy), and the advice I received was that the fix was expensive, but if I keep the oil at the proper level, it would be an annoyance but no harm to the car. The car drives just fine by the way, and I’ve been adding oil for a couple of years (at least).
OP, do you live in a state with required smog checks? If you’re smoking oil, you may have a problem passing that.
Note the recent nearby thread on the increasing saltiness of the Dead Sea: New water keeps coming in, bringing some new salt, and existing water there continually evaporates leaving its salt behind, so the sea keeps getting saltier and saltier.
If you just keep adding new clean oil to replace the disappearing oil, something similar might happen: The oil gets dirty, and as you keep adding new oil (without totally replacing it), the existing oil could keep getting dirtier and dirtier. What color is the oil that you see on your dipstick? Is it somewhat transparent brown (looking something like maple syrup)? Or is it black like ink?
If you live in any of the civilized jurisdictions within the 31 states where regular emissions testing is a requirement for plate renewal, you may have more than “shame” to worry about.
We have emissions tests, and so far, no problem passing them.
Maple syrup.
Hmm, I do get your Dead Sea theory. But even if that’s true (if I’m following), the contaminants that remain (if they are the salt in the analogy) would still ultimately be diluted within a full complement of oil, and the oil would be no less dirty (but no more) than if I wasn’t burning and replacing oil. I think. IOW, unlike new salty water, the new oil has no contaminants. But the “old” contaminants could still be in there, obstinately refusing to burn a portion through the tailpipe along with the oil. In which case, my frequency for changing oil, whatever it was, wouldn’t be affected.
Not to mention that adding a quart of oil a week for two years involves a cost (based on $5 per quart) of about $400. Could probably have actually fixed the problem for not much more than that, with the side benefits of (a) not having to constantly buy oil and fill up, (b) having a healthy engine that is likely to last longer, and (c) not driving around in an environmentally irresponsible fashion.
Way less cost than that. I buy it at Walmart, in 5-gallon containers. And unless I’ve been misinformed, this is not a $300 or $400 fix. I’ll probably be getting a new car soon, I’m not spending one or two thousand to get this fixed.
Besides, I’ve already acknowledged my horrible shame. Can someone actually answer the question posed?
Hey guys, the OP has been driving it this way “for years”, I think that the Pass DEQ test has been addressed by now.
Stratocaster, The salt sea analogy is a good one. Change the oil per Toyota recommendations, and you will be fine. Consider the extra oil used as cheap insurance against the engine tossing a rod.
I applied this theory to a 1980 Honda Civic when I was young. Since I was adding a quart every couple of weeks, no need to change oil. Result was: I was soon adding a lot more.
ETA: my adviice is get rid of it and get a good used car.
New car soon? How soon? If you’re leaking the oil, you’re diluting the old oil with about 1/4 fresh oil every week. If it’s burning the oil, the old oil gets polluted faster due to the blowby in the cylinders that is causing the oil burning. Therefore, topping up a leaker could stretch the oil’s life (anyone’s guess as to how much) but running an oil burner shortens the oil’s life.
I once ran ten quarts of oil through a '73 Vega (Vega oil burner- who’d a thunk it?) on a 3000 mile trip. The oil I drained after that trip was as black as coal.
It depends what the problem is. If it’s a head gasket it’s going to much, much…much much cheaper than a ring job.
Also, you’re going to need to change the oil filter once in a while. Probably more than once in a while if you’re never actually putting all new oil in it.
As for the salt sea analogy, I’ve thought about that in the past with these issues (you’re not the first person to wonder about this issue), but in all likelihood, the contaminants are burning with dirt and leaving with the old oil. If whatever breach in the engine that was letting the oil make it’s way though to the combustion chamber was so small that oil could get past but not dirt/carbon, it would probably get clogged up pretty quickly.
When it gets bad enough for the state or local police to stop you, then trade or junk that car & get a different one.
I played that game way back when I could get the dregs oil in mason jars that the gas station still would place the oil cans used for oil changes in a home made rack so it drained the last bit of oil into the mason jars.
15¢ a quart. Great stuff for a kid with a part time job keeping his beater running.
I’m surprised somebody hasn’t mentioned this already … the oil filter.
The filter just gets dirtier & more full of gunk over time. And once it gets gunked up enough, it starts interfering with the flow of oil, leading to inadequate lubrication of moving parts. When you change the oil, you also change the filter for a fresh clean one.
THIS is probably the main reason why nobody advocates giving partial mileage credit between oil changes for replacing burnt or leaked oil.
My advice to OP: With an aged, infirm car you’re trying to nurse along for an extra few thousand miles, doing oil changes on time is not the place to skimp on maintenance. In fact changing oil on time to a bit *early *is probably the cheapest keep-er-goin’ insurance you can get.
Good thoughts, thanks to all. To be clear, this was more curiosity than anything else. If anything, I get the oil changed more frequently than Toyota suggests. I was wondering, but not really concerned about skimping for the sake of a few bucks saved (short term). I get the filter changed, etc. My dad was not a car guy either, but the one thing he emphasized with me was that changing the oil timely was crucial.
Joey P, I suspect that’s right re: the salt sea theory, in which case the oil would be a bit less dirty than it otherwise would have been. But from what I’ve read in this thread, nothing to depend on, and there doesn’t seem to be some sort of “rule of thumb” that says how much it might push out the need for a change.
