Well gang, I'm starting to wonder if my truck is worth the new tires I just put on it! The past 3 oil changes on my 1998 5.4L F-150 4x4 ext cab, I've noticed that about 2000 miles after the oil change that when I check the oil, there is barely any oil on the dipstick. Best case scenario is there'll be oil up to the "min" mark on the stick.

So obviously I'm using or losing oil somewhere, but where, and how much? I don't notice any oil in the water, no burnt smell to the oil on the stick, no blue smoke at all, but I do notice a considerable amount of soot on the inside of the exhaust pipes. Also, I can't see any evidence of a leak anywhere.

I'm showing my ignorance here, but with the oil at the "min" mark on the dipstick, exactly how low does that make it? It can't mean there's no oil in there because there's quite a bit that drains out at the past 3 oil changes.

I'm getting really worried about this, and I'm at a loss as to what to do. Anybody here have this problem? If so, what's the deal, and what's the fix?

Thanks in advance.

 

P.S. The truck seems to run just fine, and by the oil pressure gauge, it's holding good pressure (although I know better than to trust that sort of thing completely).

Will an oil additive help? Lucas?

 

Mine leaks at the rear of the head on both banks.

Regards

Jean Marc Chartier

 

does yours leak THAT much?! I mean is that really acceptable?

 

My old ranger used to do this all the time. It used to leak burn oil so fast that by the time 3000 miles came around, I had already added about 5 quarts. Eventually, it just stopped. I didn't do anything but let it sit for about a week. That isn't the cure to it though.

 

Hmmmm...not much in the way of diagnostic info, but thanks anyways.

 

A quart for 2000 miles is not outrageous for a 10 year old truck. I have 2 5.4 engines and they both use about that. Check your oil. I buy enough oil when I do my oil change to add a couple quarts in 5000 miles. It's not that painful. deal with it.

 

Check your PCV Valve.

 

Sir, yes sir!

I wondered about the PCV as I've heard a bad one can lead to oil consumption. I haven't seen much in the way of HOW it can cause oil consumption though. You guys know how that works?

Thanks.

 

There is a vacuum on the line that is pulling the emmissions back into the system. The PVC gets stopped up, the vacuum is pulling oil up. Path of least resistance.

 

AHA! Good to know bluejay...thanks for the good info!

See? An old dog CAN learn new tricks.

 

When it gets down to the MIN line - checking the oil on level ground on a COLD engine - add 1 quart. How many miles does it take for it to get down to MIN again?

 

At the MIN mark, you still have ~ 5 qts of oil, so you are not 'empty' by any means...

Now, once you don't even see oil at the min mark, then it's anybodies guess how much oil you have left!

It's probably going out the exhaust, so check or just replace the PVC and see how it goes. At least your cats are still working, as that's probably why you don't see that much blue smoke out the pipe...

My Dad's old 1971 F250 with the 390 in it used to leak/burn so much oil that you had to add a qt every week... It got to the point where we only had to change the oil filter because there was a constant supply of fresh oil going in all the time!! This was a LOOONG time ago, and he did finally get a new 'create' motor for it and that stopped the bleeding, but at the time, it was still a daily driver, so that's what we did!

Good luck!

Mitch

 

Thanks guys...great info! If I check the oil 1500-2000 miles after an oil change, the level will be either at or below the "min" line. I'm 2500 miles after my last oil change now, and there's oil up to about 1/8" on the dipstick...not hardly to the "min" mark, and that's the lowest I've registered yet.

I'll get a PCV valve, oil, and filter tonight and out with the old, in with the new. Hopefully, that helps. Although I just remembered I changed the PCV valve about 10K miles ago. How long do those things typically last anyway?

 

I've still got the same PVC I replaced when I first bought my truck over 7 years ago!! I simply replaced it as part of my maintenance plan because the truck had 65,000 miles on it and I wanted to know when it was done!

I check it when I change the oil, and it still 'rattles' and it doesn't use anymore oil then it did when I first got the truck (~ 1qt every 3000 miles). It used that much at 65,000 miles and uses that amount at 189,000 miles... Go figure??

So, I'd say it's probably something else if you've already replaced it, or you just got a 'bad' one?? I've always thought that if you can easily 'rattle' it, then it was fine? All it does is let the vacuum pull from the crank case and recirculate it back into the intake so it burns the fumes instead of letting them just go out a 'breather' into the air, like they did on the old engines back in the day..

If it ain't dripping on the ground or going into the coolant, then it's burning....

Mitch