02 CRF 450 oil strange color


I recently bought an 02 CRF 450 from the original 55 year old owner. I was convinced I was getting a sound bike, well maintained with easy trail hours. I changed the oils and filter before the first ride and noticed the oil looked slightly off color from black, almost a dark brown or dark tan color. I rode about 2 hours and later and noticed through the sight glass that it still looked new. After a few starts and a short ride later noticed it looked like cloudy honey. So I dropped the oil and it is again a dark brown even very dark greenish tan color. After about 2.5 hours should it look this way before turning fully black? Maybe I am analyzing it too much, but has anyone noticed this type of thing before? Worried about a warped head or something. It just does not look right. Thanks!


No , the oil should not turn green or milky . It could be a leaking head gasket .

When was the last rebuild ?

I suggest a leak down test

CRF450s are very hard on engine oil, and they run less than a quart of it. The oil is going to deteriorate rapidly. Typical oil change intervals for these bikes are every 4-5 engine hours.

Don't forget about the transmission oil either.

Edited by Lead Head

if you dont have a a head gasket blown (COULD be, I just said COULD be so dont blow me up lol) condensation from the weather change i just went through this on my zx6r street. Condensation got n the bike (I left the drain plug off it over night to drain all the oil out) after a oil change and the oil turned milky white after 30 seconds in the sight window. all i had to do was ride the bike for about ten minutes and the oil was a golden honey again,(Rotella T)

OOps i didnt see th green color part of the post


The green part sounds like the oil hasnt been able to turn to milk shake brown just yet from the water/coolant in the oil. I'd pull the head off, its not the end of the world.

Thanks for the replies. It's weird, it doesn't smoke at all, starts first kick, runs great and sounds smooth, no loss of coolent. It's not a milky color, but definitely not black or honey like new oil. I'll send a pick in a moment. Never had a sight glass before, so was not sure if this was the shade before black. The oil does smell a little like gas, not sure how that could be. What kind of a job is the head gasket on these bikes? I'm new to CRFs, always had XRs. Any help is appreciated, thanks!

Here's a pic through the sight glass. This is pretty much what it looks like in the oil pan. Seems that I was duped by a pretty bike! Should have known better!

Here's a pic through the sight glass. This is pretty much what it looks like in the oil pan. Seems that I was duped by a pretty bike! Should have known better!




you bought a 11 year old MX bike. dont buy an old bike that has been used expecting a new bike. You will have to put some coin into it

I would guess a head gasket and also possible oil migration in the case between crank and tranny. Also inspect the vent hose from the head, it T's and goes down by the shock. Stock there is a cap there. Pull the cap and drain the hose. If the hose was full it could cause all the water and gunk to get sucked our poured back into the head.

if you do pull it down here is what I would suggest minimum:

new crank

new piston

new head (bigbore thumpers are ready to run)

new balancer shaft bearings and seal

new water pump shaft, impeller (06-08) and seal/bearing kit

inspect the clutch. Im sure the chassis and linkage bearings need help. Like wise with the suspension needing servicing with new fluids. inspect the brakes, replace worn parts

That dont seem milky enough for a bike with a blown head gasket and 2.5 hours on it. How does the plug look, is the bike jetted emtremely rich??? would be so rich yours getting gas in the oil??

how long was it sitting before those pics?

did you add too much oil, and its foaming up?

and what oil are you using? some kinds foam worse than others.

The only thing i see is the level being a little high, unless its been sitting for a week. The oil color looks fine. If there was coolant in the oil, it'd be a milkshake foamy brown color, even after sitting.

Thank you everyone for the comments. To the guy who said everything needs rebuilt, the guy had receipts for recent rebuilt suspension, linkage, top and bottom end with new kibble white valves. He claimed only 10 hours on the engine and it sounds and rides like it. I simply have never seen oil look anything but new or black. It looks full in pic due to leaning on the kickstand. Most of my question was; what does your oil look like when you guys change it after a ride and has anyone else noticed it look weird? Thanks!

Ive always said these sightglasses can play a trick on you. Ive drained oil before cause it would look dirty in the sightglass and when i drain it in the pan it looks clean as can be then i was cussing haha.

I'm not an expert but that oil looks fine to me. I was concerned about this very thing on my 03 until I changed the oil and realized how dark the NEW oil was before I put it in. I use Honda 20w50 in mine. These bikes use less than a quart...that is not a lot and it will become dark rather quickly. That's why oil changes are frequent on these bikes as others have mentioned. Hope this helps! Ride on! :ride:

Thank you Nick_C18 and the other replies! I have decided to flush the case with several warm up, dump and refil with cheap oil several times then go back to good synthetic and see what happens. I have not ridden the bike much and I know it sat for a year or two before I bought it, maybe just condensation. Thanks again! -Kyle

Mix just a little bit of ATF in with your motor oil while doing your fluching cycles. DOnt run it in there long but it has more detergeant in it. It will help clean your whole system

what about checking your crankcase drain plug/tube. could be overflowing and in need of emptying

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