High mileage without very dark oil - possible?

drypowder

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When you get over 100k miles, is it expected that the oil will be pretty dark after 5k miles? If not 100k, what's the mileage where dark oil is the norm, and light oil is the exception 150k, 200k?

Also, is dark oil in a vehicle with good compression (tested using compression gauge) anything to worry about, or can you still expect lots of life out of the engine (with regular oil/filter changes of course)?

Speaking of compression testing, I gather this isn't part of the usual pre-purchase inspection. Seems like checking compression is prudent when buying a used vehicle - am I wrong here? Any ballpark estimate of how much a shop would charge to add a compression test to a PPI (let's assume inline 4 cylinder engine, as I know some larger engines require differing amounts of work to access spark plugs)?
 
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Some oils have additives that darken quickly, the darkness is also particles that are too small to filter out.
How does the oil feel when you wipe the dip stick with your fingers? Smooth or thick?
Disclaimer: I am not a mechanic by trade.
 
With 100k on the odometer, your oil will get dark fairly quick.....as in less than 1000 miles. All it probably means is that your oil is doing its job.

Your compression test gives a general inication of the interal "tightness" of your engine.

If compression, oil pressure and temperature is good..... The mechanics of your engine and cooling system should be ok.
 
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Engine oil (I believe) gets dark from just being heated up, like a cast iron pan.
It gets darker faster from leaky valve seals an piston rings slipping past burnt carbon from blow by.
 
If the oil is still a gold-amber color at that mileage....it means someone recently changed it. Testing the compression and oil pressure is a good idea before buying. A compression tester and oil pressure kit arent that expensive and the tests are fairly easy to do.
 
Just me 2 cents.

In more modern vehicles it seems to me that the oil stays cleaner longer. We had an 02 Ram with 220k on it and the oil would never get super dark. It would pretty much change from new goldish color to a dark amber.

Same thing with our other vehicles with 100-150k. We have a 14 Chrysler v6 with 98000 on it and 8k ish synthetic oil changes and the oil always looks barely darker than new.

Same with my current 03 Suburban with 150k and 3-5k conventional oil.

My diesel is a different story lol. That always turned black instantly.

Oils and additives are definitely better than they used to be and engines run cleaner.


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My personal experienes are with Toyota, Nissan and Jeeps if it helps. I replaced the timing assembly on a KA24E nissan at 100k and changed the oil at 500 miles afterwards......it was dark. Compression and oil pressure were well within spec. I used to change the oil in my jeep once a year no matter what mileage.....and because it was a seconary vehicle it was usually in the 2500-3000 mile range... It was also dark. These were both late 90's to early 2000 vehicles. Our most recent is a 2008 toyota....the oil is dark at 5k.
 
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You can put oil in your car and drive 50 miles, it will be dark. From heat cycles and keeping partial in suspense. Modern cars run a higher oil temp to help/offset EPA standards....every manufacture of engines or products with engines that are under EPA radar does this.

Min shop rate is half a hour. If it rolled in already warm, half hour labor.
 
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As far as oil goes, pretty much what has already been said.
As far the compression test goes, I wouldnt sweat it at 100,000 unless suspected driveablity issues are at hand. Maybe at 200,000.
 
Switch to amsoil and the oil won’t get dark.

I have replaced two engines that the owners were using amsoil. The Toyota camry 4cyl had oil starved top end due to clogged filter. 130,00 ish miles.

The uncle of the Toyota vehicle had a Dodge van crap a motor at about the same mileage, seized rod bearing. Culprit, clogged oil passage.

Dont think it was the brand of oil as it was the service interval.

Just recently passed on a Chevy traverse just over 100,000 miles with a trashed timing chain. Again, stupidly long oil change interval of 15,000 ish miles between. Dont know what oil he was using.
 
got over 200,000 on 3 of my vans. change every 5000 miles. use wally wold oil and filter (filter is a champion, but all oil filters are the same, really only the filter element is different) oil is dark, but still slick. as was evident when i slipped on the quarter size drop in the garage and fell and busted my ass this morning when changing it.
 
I have replaced two engines that the owners were using amsoil. The Toyota camry 4cyl had oil starved top end due to clogged filter. 130,00 ish miles.

The uncle of the Toyota vehicle had a Dodge van crap a motor at about the same mileage, seized rod bearing. Culprit, clogged oil passage.

Dont think it was the brand of oil as it was the service interval.

Just recently passed on a Chevy traverse just over 100,000 miles with a trashed timing chain. Again, stupidly long oil change interval of 15,000 ish miles between. Dont know what oil he was using.

Yeah 15,000 is a wee bit too long. I usually go 7500-10,000 with amsoil.
 
With a tight low mileage engine.......you could possibly go 25k between oil changes using amsoil......but you still need to change the filter every 7500 miles or so. There was an article on this in JP??? Magazine several years back when synthetic oil was the new craze.
 
Cars are like women ( and I a sorry for being and old white guy in advance to anyone who gets offended..)

You can treat one like crap, abuse the hell out of it and it will love (run) forever..
Next you treat like a queen, and she will do you wrong ( leave you on the side of the road)...

Hope for the first, plan for the second!
 
The BMW M5 or X5???? Suv had a long oil change interval.......because it had a huge oil tank, as in 10+ quarts. Reality.......you still need to change the filter every 5 to 7.5k miles. Most experienced mechanics still recommended 5k intervals.
 
When you get over 100k miles, is it expected that the oil will be pretty dark after 5k miles? If not 100k, what's the mileage where dark oil is the norm, and light oil is the exception 150k, 200k?

Also, is dark oil in a vehicle with good compression (tested using compression gauge) anything to worry about, or can you still expect lots of life out of the engine (with regular oil/filter changes of course)?

Speaking of compression testing, I gather this isn't part of the usual pre-purchase inspection. Seems like checking compression is prudent when buying a used vehicle - am I wrong here? Any ballpark estimate of how much a shop would charge to add a compression test to a PPI (let's assume inline 4 cylinder engine, as I know some larger engines require differing amounts of work to access spark plugs)?
Yes its expected to have the oil darken after 100K miles, some engines do it sooner then others for a number of reasons. Oil darkens due to a by product of combustion and its called carbon. Carbon is black and this is what darkens your oil. As your engine wears, the piston rings don't seal quite as well and allows these combustion gasses to escape past the piston rings and contaminate your engine oil. Compression testing is a great tool for diagnosis when you have a known problem like a cylinder misfire, but a cylinder leak down test will give you a much better health report of your engine components to include the valve sealing and the piston ring condition. The results of any tests you might have requested will be skewed by the technician's skill level..
 
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Since this is only one example it won't mean anything statistically but this is what I did on the advice of a Petroleum Engineer 20 years ago. He had been involved with a test in Germany with the BMW folks in 1998. On his advice at the first 3,000 mile change I refilled with Mobile 1. That was in a 1999 Ford 3L V6. Since that time, every 7,500 miles I change the Filter and add a quart of Mobile 1. It now has 126,000 miles on it , if you pull the stick on it right Now, the oil looks like it did when it was put in. It's here, if you want you can stop by and pull the stick anytime. Again, this is my experience. I'm not telling anybody to try it. This is what happened to me.
 
Yes its expected to have the oil darken after 100K miles, some engines do it sooner then others for a number of reasons. Oil darkens due to a by product of combustion and its called carbon. Carbon is black and this is what darkens your oil. As your engine wears, the piston rings don't seal quite as well and allows these combustion gasses to escape past the piston rings and contaminate your engine oil. Compression testing is a great tool for diagnosis when you have a known problem like a cylinder misfire, but a cylinder leak down test will give you a much better health report of your engine components to include the valve sealing and the piston ring condition. The results of any tests you might have requested will be skewed by the technician's skill level..
Agreed and; Conventional multi viscosity oils (like a 10W-30) are a 10 weight oil with plasticizers added to make it act like thicker oil at 200F. The plasticizers darken quickly with heat.
the 10W-30 means at 0F it flows like 10 weight oil, and at 200F it flows like 30 weight. The "W" means winter.
If the previous oil was loaded in contaminants that couldn't be suspended anymore, the fresh oil with its detergents will quickly dissolve them and darken.
 
Agreed and; Conventional multi viscosity oils (like a 10W-30) are a 10 weight oil with plasticizers added to make it act like thicker oil at 200F. The plasticizers darken quickly with heat.
the 10W-30 means at 0F it flows like 10 weight oil, and at 200F it flows like 30 weight. The "W" means winter.
If the previous oil was loaded in contaminants that couldn't be suspended anymore, the fresh oil with its detergents will quickly dissolve them and darken.
Interesting, so the viscosity extenders are actually called plasticizers ? That's something I didn't know..Thank you..
 
Interesting, so the viscosity extenders are actually called plasticizers ? That's something I didn't know..Thank you..
If my memory serves me (it's untrustworty except for unimportant things) they're long plastic molecules.
Decades ago I had been curious for some time, and finally found a detailed article from a R&D lab that explained the numbers, types, additives in motor oil. Back then synthetics weren't (I'd never seen, nor heard tell of) labeled multi-viscosity because a 30 weight Mobile1/Red Line tested as a 0W-30.
 
Dirty oil just means you have cleaned a bunch of shit out of your engine. Dirty isnt bad if you are changing your oil regular. I rarely go over 3500 with synthetic in my liberty at 175k miles.
 
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