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Should I change oil as soon as it turns dark?

I’ve been using synthetic oil cos’ I don’t want to change it regularly. The oil is usually advertised to be good up to 15k miles or 1 year. However, it turns dark after 3-4k miles and I’m worried about it. Sent a sample to Blackstone lab and they said it was fine. Shall I keep driving till 15k miles?

Too many variables, what are you driving? Under warranty or not, what does your manual say, what kind of driving in what kind of temps, how many miles do you drive in a year, and How many miles/years do you want to get out of this car?

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A very very important thing to keep in mind when using synthetic and leaving the oil in use for a long change interval is that you MUST check the oil level regularly. Engines consume motor oil as part of their normal operation. Some consume more than others. A quart consumed during a 3K mile change interval is common and use can go up from there as a quart every 1K miles has been reported and still considered “normal”. You will need to be checking your oil level once a week or once every 2 weeks throughout the entire interval. You cannot just fill the engine and close the hood and forget about it for 15K miles…it doesn’t work that way. This is how many people destroy engines completely and it happens very often.

Personally the reason I don’t look to go anywhere near a 15K mile oil change schedule relates to something you mentioned in your post…about the oil turning black. The oil turns black because of soot from combustion. So the more fuel you burn during the change interval, the more soot particulates build up in the oil. So how much soot do you want in your engines life blood before you change it with new oil?

A proper running engine usually doesnt ask for much, changing the oil is the very least you can do to help it perform the difficult job it is enlisted to do for you. It is perhaps the most important thing you can do for your engine and it is also perhaps the most ignored or abused facet of car maintenance. Makes absolutely no sense to me, but there you have it…


Mine has an amber color after 12k miles…not dark. What type of vehicule do you drive?Did you take your sample on the dipstick or from what came out of the crankcase?

That’s all you need to know.

It’s 09 Honda Accord 3.5 v6. It has about 170k miles now. I found it weird that the any type of oil all turn dark at similar mileage(4000). Perhaps the fuel burning efficiency of the car is low so there is more soot?

You’re overthinking this. Blackstone’s analysis said your oil was fine, so stop obsessing over its color.

Maybe but the normal sample cost is $29 last I checked but another $10 for the longevity test. I’ll be sending in a sample soon just for the fun of it, but I don’t care about the longevity test. Are we sure that the OP is spending $39 plus postage to get the full test? Like I said, a filter costs me $5 and 5 quarts of Mobil 1 cost about $25. I change oil every 5000. For less than the cost of a sample, I can do an oil change. Would I buy a used car with 15,000 oil changes? Not on your life, which is prolly why I’m just not going to buy used anymore.

I don’t think we need to re-litigate a very old debate about the time span between oil changes to answer this OP’s questions. He already spent the money on the test, and now he’s getting all OCD about the color of his oil.

I think it’s a waste of time, energy, and attention to obsess about the color of the oil you drain out of your car, especially after you’ve already done a used oil analysis. If you’d like to discuss that rather than change the subject to one one we’ve debated dozens of times already, I’m game.

The OP is changing synthetic oil once a year, and Blackstone confirmed the oil was fine. I don’t think continuing that practice will hurt a thing.

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Actually regardless of how many miles I’ve had on oil (and that will range from 7 to 5000), the oil always looks dirty when I drain it. It may not look black on the dipstick but always in the drain pan. So maybe the question is how you determine how it looks without draining it. Plus to do a proper sample, you need to take the sample from the middle of the drain.

That’s true. Even when I was doing 3,000 mile oil changes back in the day, the oil came out of the drain black as night, but still looked clean on the dip stick.

The manufacturer is telling you that there are enough additives to keep the oil form going acidic for 15,000 miles. If you drive over 15,000 miles in a year, you might want to recheck your oil at Blackstone in another 4000 miles. If it’s still good, do it again at 12,000, then again at 15,000 when you change it. If you do 4000 miles a year, then you would go almost 4 years before changing the oil. I wouldn’t wait that long, but would do it annually. I had a 2005 Accord EX V6 and it used mineral oil, not synthetic. I imagine Honda says you can use mineral oil, too. I changed oil between 7000 and 7500 miles until I traded the car with 186,000 miles on the clock. The used car manager remarked how well the engine ran for a car with that much mileage.

Yeah the salesman asked me the same thing when I traded my Buick with 500,000 miles on it. I said I change oil every 3000 miles and he said I knew it.

I think you’re both putting too much stock into the things salespeople tell you to make you feel good about yourselves.

Thank you, Major Downer! :wink:

They not only said, it they backed it up with a better trade value than I expected. They like the AT, too. I changed fluid every 40,000 miles.

What made me feel good is that I got $500 for it. Yeah I know it’s all hidden but still.

Contrary to popular belief using synthetic oil doesn’t automatically mean you don’t have to change your oil regularly. Best practice is to change the oil per manufacturer’s specified intervals. Using synthetic oil does grant you superior lubrication, and wear resistance vs. dino oil, but it’s not a case where you suddenly don’t have to change it regularly.

That’s longer than I’d willing go between OCI’s. On a modern car with a modern synthetic or blend most manufacturers spec 7500-10,000 mile oil change interval or 1 year which comes first. I generally go around 6000 miles, as most of my driving is short trips (my commute to work is barely 5 miles on two lane roads).

The color of the oil isn’t an absolute when it comes to determining it’s condition. Diesels will turn golden oil, black in a matter of hours, however the oil is still fine.

That’s kind of baffling to me, you don’t want to change the oil, but you’re perfectly willing to send a sample to Blackstone? It probably would’ve been cheaper just to change the oil again.

You can do what you want. I’d change the oil per the manufacturer’s specs.