oil in the plenum...

gotchopsticks · Jan 10, 2009

so i was cleaning my K&N and noticed there was excessive crap in the intake tube. so i removed the tube and cleaned it out. i looked into the plenum (opening the throttle plate) and saw there was a decent layer of black inside the plenum on the wall adjacent to the firewall and the wall perpendicular to the firewall. i checked inside the return hoses coming from the PCV (passenger side) and the other PCV(?) on the driver side and there is oil in the hoses. there was enough oil to drip out if i tilted the hoses. i checked the level of the oil when i changed it next and it was missing almost 2 quarts. there is just shy of 65000 miles on the car and it has serviced regularly since i owned it (29k). i am using Castrol Syntec 10W30 cuz i live in southern cali. any suggestions? thanks.

SONIC02 · Jan 10, 2009

Install an oil separator. You can get one from steeda or make one yourself from lowes. Search Oil Separator and you should find all your answers. The oil in the tube is normal.

gotchopsticks · Jan 10, 2009

thanks. i can always count on stangnet

BurningRubber · Jan 10, 2009

What interval are you changing the oil? You should not be down 2 quarts, and definatly should not be driving with 2 quarts missing.

Some oil passing through the PCV system and back into the intake is normal. A little oil/dirt buildup in the plenum and on the back of the throttle body blade isn't a huge concern.

Have you changed the PCV valve at all? Maybe it is stuck open.

gotchopsticks · Jan 10, 2009

every 3000-3500 miles. let me rephrase: it used almost two quarts within one oil change. i noticed the level was kinda low so i added 1 quart, and when i changed the oil i filled the empty bottle with the used oil and it only filled 5.25 bottles, so i figure it burned the difference...hopefully not because of bad rings. no i have not changed the PCV, but which one is the PCV? i noticed there is a fitting on both valve covers that is connected to the intake system. hope i dont sound like a complete noob with that question...

98COBRA281 · Jan 10, 2009

the pcv is on the passenger side, it only like $3 or $4 bucks at auto zone...........

gotchopsticks · Jan 10, 2009

whats the one on the driver side? vacuum?

BurningRubber · Jan 10, 2009

I believe it's a vent to work in conjunction with the PCV valve.

A quart every 3k is about what I use also.

However when you change your oil, there is a bit that stays in the oil filter. So if you were to drain that amount you would be alot closer to the 6 quart mark.

If you are worried about the rings bieng bad, I suggest a compression test. Testers aren't expensive and it's easy to do.

gotchopsticks · Jan 10, 2009

its not a quart every 3000k, i added the first quart at around 1200-1500, and then was still missing almost another full quart when i did the change. and in regards to the oil filter: i use one of those large black oil collectors when i drain the oil, and when i take the filter off i dump any leftovers into the same container, then fill the empty bottles, so it is also counting the oil in the filter. maybe i should try a more viscous oil to prevent so much from going through the PCV system? im running 10w30 syntec now with a moto 820S filter

i will definitely get a leakdown test next time i change the plugs. thanks

BurningRubber · Jan 10, 2009

Alright, gotcha. Sorry for my mis-understanding.

I wouldn't suggest running a thicker oil though. The tolerances in these engines are pretty tight and they need to stick with a lower viscosity oil.

Your manual should call for 5w20.

gotchopsticks · Jan 11, 2009

ya you are right, even the filler cap says 5w20 on it and i have been running that up to one oil change ago. i heard that as the engine gets older more viscous oil should be used, plus synthetic is a bit "thinner" than regular oil; but then again, i only have ~65k on the motor. shouldn't the ambient temperature also be taken into consideration? i understand why a less viscous oil would be used in, say, Minnesota or Main, but i live in Southern California. for instance, its the 11th of January, 12:46am and its almost 75 degrees outside...

BurningRubber · Jan 11, 2009

Yeah, tempature does go into play, but where you are at 5w20 would be fine as called for.

If it's REALLY hot out 5w30 would be a better choice, as the oil will thin the hotter it gets. Super cold climate step it down to a 0w20 or whatever, for example.

First # is the cold viscosity rating, second is the oil at tempature rating.

65k you shouldn't have much to worry about...

gotchopsticks · Jan 12, 2009

Ok, then i'll take this stuff back and do 5w20 until the next change, and then do 5w30 for the warmer weather. durring summer its in the tripple digits for months at a time

thanks for your help, i look forward to many more miles. any idea how many miles these motors are good to if properly maintained? some of the vids on here show stangs with 160k+ and still running hard, but who knows if its the original motor.

GettinThere · Jan 12, 2009

Replacing the pcv valve with a motorcraft one every 30k miles should help. It's just too bad that getting the right pcv valve has been surprisingly difficult.

BurningRubber · Jan 12, 2009

Not a problem.

With proper matinence there are a few Mustang guys that go 175-200k without troubles.

Think of all the taxi's and police cars that use 4.6's, they have 3-400k on them before they retire on the origional engine, alot of them living really abusive lifes.

gotchopsticks · Jan 12, 2009

haha, wow, i've owned the car for 4 1/2 years now and i've only put 35k on it, guess it will last me another 50 years at this rate, if there is still gas then

pepboys doesnt even list a PCV for the gt or mach, just the cobra so i'll be checking my local Napa or Autozone

oil in the plenum...

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