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I bought a used 2005 yz450 and first thing i did was change the oil, it came out real black and dirty. I didn't have a filter so I left that alone. As soon as I fired it up to check the level the new oil was dirty. So I go and get a filter and some more oil and change it again. It still comes out real dirty right away. how fast does your guys oil turn dirty, I would think it should last longer than this.

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I bought a used 2005 yz450 and first thing i did was change the oil, it came out real black and dirty. I didn't have a filter so I left that alone. As soon as I fired it up to check the level the new oil was dirty. So I go and get a filter and some more oil and change it again. It still comes out real dirty right away. how fast does your guys oil turn dirty, I would think it should last longer than this.

Are you starting the engine and warming the oil for 3-5 minutes before draining?

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I change my oil after every ride, filter every 3 rides and use a magnetic drain plug. That helps to get the oil clean but it still comes out dark. Change it frequently, get a magnetic drain plug and change the filter every so often. My 02 426 and 99 400 engine oil looked cleaner than my 03 450 even though I did the exact same things to all 3 bikes.

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A dark color is not always an indication of dirt, or anything else negative. Sometimes, of course, it is, but it can simply be a reaction of the base oil or additives to a normal amount of heat.

I would not have bought a bike that had a dipstick come up black, but moving on from there, if the oil was left in place for too long, you will have to do about 3-5 changes before the new gets all the garbage collected. Remember that the oil filter well holds about 100cc of dirty oil, so that's where some of it comes from. You should buy a Scotts stainless steel mesh oil filter and clean it with every oil change, and you should be changing your oil every 3rd ride AT LEAST. For me, 3 ride days occasionally reaches near 10 hours, and that should be about the max. Any race day should start with clean oil, and get an oil change afterward.

If you are getting black oil out of a "clean" engine, there could be a couple of problems. You might be getting an excessive amount of fuel contamination or combustion gas blow by, and/or the oil may be oxidizing excessively. If neither a too-rich condition or excessive blow by exist, consider a different oil.

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A dark color is not always an indication of dirt, or anything else negative. Sometimes, of course, it is, but it can simply be a reaction of the base oil or additives to a normal amount of heat.

This is absolutely true, my dad owned a machine shop for 26 years and he has always told me that the color of the oil indicates nothing. The only thing you can tell from oil alone is whether or not you have a problem with any internal parts based on having metal shavings metal shavings. Consistency changes can tell you whether or not you are changing your oil enough.

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  • 4 weeks later...
A dark color is not always an indication of dirt, or anything else negative. Sometimes, of course, it is, but it can simply be a reaction of the base oil or additives to a normal amount of heat.

If you are getting black oil out of a "clean" engine, there could be a couple of problems. You might be getting an excessive amount of fuel contamination or combustion gas blow by, and/or the oil may be oxidizing excessively. If neither a too-rich condition or excessive blow by exist, consider a different oil.

Hey grayracer

if the bike was jetted too rich do you think that it would cause the oil to get dirty? i don't know how to check for blow by but the bike seems to run so well and it doesn't use any oil, it just won't stay clean. Now I am not talking dirty in 2 seconds, it takes about half to 3/4 of a tank on pretty hard riding and it starts to look pretty dirty. any ideas? anybody

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any ideas? anybody

If you didn't change the oil filter that's probably what's darkening the oil. If it has been left in there a long time you really need to change it. I just got one of the Scotts SS filters grayracer mentioned and it appears to be a really high quality unit.

I also have to wonder if maybe your clutch plates are burned up a little which would also cause darkening...

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Hey grayracer

if the bike was jetted too rich do you think that it would cause the oil to get dirty? i don't know how to check for blow by but the bike seems to run so well and it doesn't use any oil, it just won't stay clean. Now I am not talking dirty in 2 seconds, it takes about half to 3/4 of a tank on pretty hard riding and it starts to look pretty dirty. any ideas? anybody

You have to go back to the first time you changed the oil and found it "black and dirty". If the oil had been in the bike too long, it will have lost its ability to absorb, suspend, and neutralize the fine solids and liquid contaminants it picks up. These will be deposited on every surface the oil comes in contact with, more so on iron and steel than on aluminum (steel has a greater affinity for these deposits. Then, you changed the oil, but left the filter in. That means there was 100cc of old oil that you won't ever get out anyway, and another 100cc in the filter. If it's a paper filter, the new oil will wash out some of the finest debris stuck there and return it to the oil supply. So, with each 1 quart, leave-the-filter-in type oil change, 17% of the total oil supply in the engine is old oil. It may take 5 or 6 oil changes to completely clear the deposits from the oil tank to the point where you won't see them anymore.

A rich condition that is bad enough to cause significant fuel contamination in the amount of time you speak of could be the cause, but it seems a bit extreme.

So far, you haven't said what oil you are using. As I mentioned earlier, so oils darken on exposure to heat, and in many of those cases, it's because the oil does not resist being oxidized as well as it should. If you are not using a good high quality synthetic motorcycle or heavy duty oil, I suggest you try one and see if you get different results using that. Of course, you could always have an oil analysis done.

Read:

https://www.thumpertalk.com/forum/showthread.php?p=2685432#post2685432

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You should buy a Scotts stainless steel mesh oil filter and clean it with every oil change, and you should be changing your oil every 3rd ride AT LEAST. For me, 3 ride days occasionally reaches near 10 hours, and that should be about the max.

I am considering taking my 00 YZ426F to Baja next year but I am concerned about service intervals. If you suggest changing oil every 10 hours at a minimum, that would mean that I am changing oil everyday. At 1.5 liters per change minimum and riding 5-7 days in the desert, the amount of oil I would have to take along seems outragous. What are your thoughts? Can this interval be safely extended?

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Well I assume the intervel of oil changes on the 450F is a little differant from the 426F. The 426 can hold more oil. So I would assume that you can go longer on the oil. My '03 has gone 25 hours without an oil change and it looked fine. It was starting to turn dark but it was still pretty clear. I use Castrol GTX 10W40 and it seems to work fine for me. My dads '02 WR250F has been using the oil listed above for a good year now and we havent had a single problem with it. Havent even had to touch the motor, clutch, or transmission.

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So do you think that I could get away with one oil change over a 5 day Baja trip assuming I start with a fresh oil change at the beginning of the trip?

I just picked up 3 quarts of Yamalube Oil. Is there any benefit in using this over any other oil?

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You can do your Baja trip without changing your oil. Everyone on here changes there oil way to often! ? I have a 03 450 that I changed the oil 3 time's per yr and the bike has been and still is perfect. While I prob. should of changed a little more there is no way the oil needs changed before and after a race or after 2-3 rides unless your up to your tank in mud/water or clutching the heck out of the bike. Change your oil go ride the baja and dont worry about it your bike will be fine. ?

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