I used Pennzoil High Milege 75000 oil this last oil change. I left it in for 5000 miles like I always do. When I drained it this past weekend I noticed a S*** load of light brown skim in the oil drain pan. I assume it's sludge, though I must confess I've always taken care of my cars mechanically an have never seen it (sludge that is). Does anyone have an opinion what is actually is? Sludge? Is it caused by the oil? 5000 mile drain interval? or possible the hybird air intake my brother in law put in the car (bought the car from him)? I though maybe it was dirt from the air intake and I should put the stock box back in.

 

sludge is black & gooey. not likely you have sludge with 5k OCIs.

look inside the oil filler hole, does it look clean in there? or coated in black goop?

did you keep the old oil filter? cut it open. if you have sludge you'll find it caught up in the filter.

was the "brown skim" floating on top? was it foamy at all? light brown foam is usually a sign of coolant and/or water contamination.

in any case, I would put the stock air box back on, and use the OEM nissan air filter.

 

Hey thanks. Bad for me it was foamy and brown and I've been adding coolant to the overflow tank, since it has been slowly disappearing. F*&% me! I suspected coolant in the oil. Any ideas what could be the cause? If I remember correctly that's caused by a leaking head gasket? right? Hopefully something less nasty.

The car has never overheated, I've owned it the past 5.5 of 6 years. It seems strange the head gasket would leak.

 

hate to tell you, but it sounds like coolant. the worst part of this is coolant in your oil is absolute *murder* on your engine. turns the oil into an acidic slurry and really eats up your bearings, etc.

most likely cause is the head gasket, but it could be something else (water pump?).

here's what I'd do (in order):

1) check the plugs for deposits. coolant in the CC will cause deposit formation on the plugs. (do this right away)

2) compression check. (do this very soon)

3) Oil Analysis -- this is a MUST. but wait until you have >1,000 miles on this new oil. then take a sample and send it to http://www.blackstone-labs.com/
they will tell you how bad the coolant situation is, and how much damage it is doing to your engine.

4) keep changing the oil very often. like every 1000-1500 miles until you get a handle on what's going on. just use the cheapest oil you can find (walmart), and cheap oil filters.

please report back what you find.

 

Sounds like a head gasket


how slowly is the coolant going down?

It its real slow, i would reccomend going to big lots, walmart, etc... and buying the following :

Make sure you get the brown stuff (its cheap too...like 90cents at biglots, 2x that at others) and run 2 or 2.5 tubes of it into your cooling system.


Others are going to disagree with me, the reason i reccomend this is because i have used it with success both in an old chrysler with your same symptoms, and i run it every time i change the coolant on my Allante, as cadillac says its needed for the 4.1 and 4.5 series V8's (although they reccomend GM ones which are the same, just not crushed up). Don't run any others as they may gum up your cooling system, but this stuff should just stay in solution.

 

if you wanna check for sludge open the oil filler cap at the top of the engine and take a peak with a flashlight.

 

^he is correct, but you should expect light varnish, just not thick sludge

 

you can smell it too...it smells worse than engine oil..kinda makes you want to throw up.....i would suggest you flushing out the system..that brown skim stuff is DEF not good.....I'm sure if you leave the drain open, n our some engine oil in..more brown stuff will keep oozing out....

 

Thanks for all the replies. I pulled 2 random plugs and I not see anything unusal. They both had light ash deposits. Regarding the smell of the oil, it only had the usual spent oil smell. I will do the oil analysis on the next oil change, but this car does not exhibit any issues. I'm surprised that a car that's never been driven hard or overheated with 90K miles would have a head gasket problem.

Someone mentioned the water pump. Is it normal for the pump to go around 90K? I assumed with a water pump I would see coolant leaks under the car.

I will try the oil analysis and post back when I know the results.

Thanks all for helping.

 

hmmm if i remember correctly i've always had that light brown foam towards the end of my draining of oil. I thought it was just the dirty oil's appearance when the last of it is dripping all the way down into the catch container.

 

I talked to a few people I know who know more about this than I do, and they think it is just "muck" for lack of a better word than coolant in the oil. This oil change I jacked the car frame on the passenger side to allow my beer induced middle age girth to fit under the car easier. This pushed the back of the oil pan higher than the drain hole and higher than normal during a typical oil change. The consensus is that is is just "muck" that would not normally drain if the car was level. I was also told that if it was a head gasket problem there would be other problems. thick white smoke from the exhaust during startup, overheating and starting problems, idling problems, and lack of power caused by coolant fouled plugs. Since my car exhibits none of these symptoms I should not worry. The engine is sometimes so smooth I have to look down at a light to see if the tach is above zero.

Don't get me wrong I appreciate the advice, except for the stop leak. One guy I talked to (not your average weekend mechanic) said that stuff was a sure way to destroy your engine. It gums up all small passages besides the hole you want fixed.

I will still do the oil analysis, but I think I'm not too worried at the moment. It probably had to do with jacking the car up.

 

muck=sludge. there should be no "muck" of any kind in the oil pan. did you look inside your oil filler cap yet? I would check all plugs, too.

a smooth idle does not necessarily mean no problems. I'm currently dealing with a 2001 blazer that is leaking coolant internally, but it runs like new despite spitting out high wear metals. you'd never know there was a problem without looking at the oil analysis.

your head gasket may be ok, but if you are losing coolant and there are no external signs of leakage, then it is going into your oil. the water pump is driven by the timing chain, which is lubed by the engine oil. if the WP seal wears out, it can leak coolant into the TC case, and into your oil.

if you find coolant in your oil analysis and can eliminate the HG as the source, the next logical place to look is the water pump.