Disappearing (burning) oil - need ideas, please help newbie

May 17, 2021
First, I'll copy others: Just stop with the additives. They rarely help and they confuse the issue. And run a 20-50 oil or so.

The first question is where's the oil going. It sounds like 'burned in the engine.' Two ways that can happen: 1. Oil splashes or sprays on the cylinder walls from below (that's how they're lubed) but the piston rings are badly enough worn that they don't scrape enough of it off so it stays on the cylinder wall as the piston goes down past it and it is then burned. OR 2. Oil in the valve train on top of the engine gets on to the valve stems (normal -- that's how they're lubed) but the seals -- little rubber or plastic caps on the tops of the valve guides that fit closely around the valve stems -- don't adequately control how much goes down between valve stem and guide.

On the exhaust valves this doesn't cost much oil -- the exhaust manifold area is under pressure. You may foul those valves with chunks of carbon which can cause other troubles but not much oil is burned. The intake valves 'suck' -- that's 'engine vacuum' which can be -10psi or a bit more. That can pull BIG OIL into the cylinder where it will be burned.

On a high miles engine in a hot climate I guarantee you that the seals are fried -- heat is murder on rubber/plastic. The seals can be replaced, that's a standard shop job though no dealer wants it because the parts are $40 and it takes a few hours labor. He'd far rather sell you a new almost anything that can be installed in 15 minutes. Thus you won't get a 'replace valve seals' recommendation from a dealer.

Cars with fried valve seals often smoke visibly when going down hill (vaccum is high, not much air going through engine). Under these conditions oil is thin and high vacuum sucks it in continuously. And/or the car may belch smoke for 30 seconds or so when starting cold and owing to the way it sat (etc.) oil has collected where it gets sucked in on startup.

In total, I'd replace the valve seals -- not a huge or expensive job -- and see where that gets you to. The next question is WHO should replace the seals. Use a search engine for 'replace valve seals (the model/engine of your car).

Replacing the seals is EASY -- no question you can do that. But to get to where you can replace them you must remove the valve keepers and caps which requires removing the valve springs. There are special tools which vary depending on the engine model, the work is 'fussy' and there's also the issue of keeping the valves closed (up).

The steps are: Remove the spark plugs, valve cover(s) and rocker shafts. Hold the valves up on the cylinders with pistons up -- if using air pressure you need like 100PSI -- not just a little tire pump. The 'rope trick' also works. Push down on the valve cap using a 'valve spring compressor' special tool until you can take out the keepers -- little curved wedges that lock in a groove on the valve stem and hold the cap on. Release the pressure and take off the cap and spring. Remove the seal from the top of the valve guide and push on the new one. Put the spring and valve cap back on, compress using the special tool, and put the keepers back. Release the pressure so the cap comes back up and everything locks in place. Repeat for each valve and cylinder.

There's no one-size-fits-all answer to can you do this: The big issue is usually how much space there is around each valve for the tool. Small engines with four (or ick, more) valves/cylinder can be hard, bigger engines with just two can be pretty easy.

The keepers are often tiny, they're fiddly to get into place, and if you drop one through an oil drainback hole into the engine you've got a problem. Good practice is close all those holes up with shop towels (etc.) before you start.

The easy way to do new seals is with the head off. So here's your choices:

1. DIY -- If after reading directions and watching a video you feel you can do it (not a hard engine ...) you could go that way. VERY cheap -- should be under $100.

2. NOT DIY -- If you want someone else to do the work the cheapest job is just replace the seals with head(s) in place. That's gonna be a small shop -- often a one man operation. Maybe four hours work, plus/minus according to total number of valves and how much space there is, whether a standard/generic tool will work or does he have to buy the special tool from the car manufacturer.

OR if you would consider keeping the truck if it were restored to run well and not burn oil (How's the body? any transmission issues? Does it do the job you want?) take it to the same small shop and for modestly more money have the head(s) pulled and the valves reground. Valve seals will be done as part of that but you'll also get 100% compression. Many relatively recent cars that haven't been abused will go 300k miles with just a valve grind. Maybe around $1000 for a shop to do it, depending on number of heads and camshaft/timing belt issues.

Variation: Pull the head(s) yourself and take them to an automotive machine shop for a valve job. On some cars that job can actually be simpler than replacing the seals. It's a bigger job -- prob'ly 10 hours or more plus machine shop time -- but there's less little fussy stuff to do. The big fussy thing is getting the head back on correctly -- torque, gasket not damaged, etc. Again, consult YouTube. AND FOLLOW MFRS SPECS EXACTLY for installing and torquing.

None of these jobs costs more than a couple-three payments on a new truck. Basically (strong opinion waning) it never makes sense to buy a new vehicle.
Dec 8, 2011
IF this were mine and you have time I would pull one head and take a look inside. pack the motor with rags so nothing falls in the bottom end. As others have posted, valves seal against the valve seat in the head, unlead gas caused issues as the lead acted as a lubricant, the repeated opening, and closing of the valve, specifically the exhaust under heat hammers the seat into the head, resulting in lost compression. Valve stem seals prevent oil in the top end from entering the combustion chamber. IT'S a simple job to recondition the head, new seals are cheap, clean the combustion chamber of carbon, rent a valve spring compressor, and have at it. Look inside the cylinders, can you see a cross-hatch hone, or are they polished smooth by wear. With the heads off soak the cylinders with seafoam, MM, or whatever. Drain and refill before starting. Good luck, use good Felpro gaskets when you rebuild.
Jul 15, 2018
Valley Forge PA
A month in and 4 pages deep, OP still hasn't had the valve seals fixed or changed oil types? Why am I reading this and why does anyone respond anymore?
Jul 14, 2020
Ivery thought about that but guess if seafoam in the crankcase doesn't work to clean coked piston oil rings then a berrymans piston soak might not clear coked piston oil rings either.

Maybe I'm wrong.....?
Not sure how we got to so many pages, I tried to read everything but my question is how do you know it's not a PCV problem? Valve seals almost never on these engines. PCV baffles plugged in the valve cover happens all the time. Causes oil usage, fouled plugs and smoke on cold start. See the pics I posted of sludged up valve cover last week.


Thread starter
Jul 4, 2021
Not sure how we got to so many pages, I tried to read everything but my question is how do you know it's not a PCV problem? Valve seals almost never on these engines. PCV baffles plugged in the valve cover happens all the time. Causes oil usage, fouled plugs and smoke on cold start. See the pics I posted of sludged up valve cover last week.
Sorry for the lapse of update everyone. I think I mentioned before moving 1800 miles and building new house. House structure finished. Most boxes are unpacked. Driveway was just poured. Another new grandkid too (I'm a youngish 52)

@350Rocket can you post a link to those pics? I tried to find them by clicking on your profile but failed to find them.

So here's the update, 350Rocket is/was on the right track. I had read/seen a few videos of the pcv issue which is really a valve cover baffle issue as 350Rocker described above. But no one (mechanics & others with same motor) I talked to in real life seemed to have ever heard of it.

I needed to have my E-braked fixed to pass TX inspection. 200k on original brakes. Then the day after inspection, I noticed gas smell when AC was not in recirculation mode. Poor mpg the tank before. Crapomatic.

Gut check time... need brakes... gas smell... going thru oil like a Kardashian goes thru men. Do I invest $$$ or dump it. Decisions and action ($$$) can't be delayed any longer

In the weee hrs of the morning before the wife woke up, I started looking for a brake shops to call when the sun comes up. Then I surfed for a new Jasper motor to compare to the rebuilts that @clinebarger offered.

While on Jaspers site (100k warranty), I find out there is an authorized installer in town (dont know why I didn't look there before... probably trying to avoid high costs) and they were listed as preferred installer or something like that. And coincidentally, they were 1 of the shops I came across for brakes. Good BBB rating and almost all praise reviews looking at various sites. The complaints were mostly stupid ones.

Sun comes up...call and start talking to them. The nice honest and knowledgeable guy says "whoaaa wait a minute... you shouldn't even be thinking of a new motor yet". That was music to my ears. Great guy... great shop.

He has a 2002 suburban with almost 300k miles (mine is 2002 Sierra w/ 200k) and he had the same problem and was familiar with the valve cover pvc issue too... he did it on his own suburban. YATZEEE!!! Or, for the younger peeps, Uber-tastic.

After a LOT of questions back and forth.... and him basically giving me confidence that its worth it to try before considering replacing or rebuilding, I decided to give it a try.

Around $1500 for new driverside valve cover where the pcv is, all new brakes and rotors, and a new fuel pressure regulator that was dripping on the manifold area (yikes).

I can't complain about the price and the service was great. Nothing but good to say about the shop and employees.

I still use oil. I haven't really monitored it very well but can can this....

I was using a qt every 300ish miles. I was at the point that I checked and added more than 1/2 qt after every gas fill up at around 200 miles (I don't run it to empty). Service engine soon light was always on for misfires.

After valve cover change and a couple thousand miles over about 3 months....

Now, oil consumption seems to be less than half. I'd say around 700ish to 800 miles. Again, I haven't monitored it super well with the busyness of moving boxes to new house etc and new grand kid.

Also, the service engine soon light went off right away. I never changed the spark plugs so I'm sure they're fouled... it did come on once I think due to poor gas... I added a can of Berryman to the gas and the light went off after about 25-50 miles and never came back on since. It runs/idles smooth - as in 'like new' smooth. Back to around 15mpg on the freeways and 12-13 around town which is real close to what I was getting when it was new.

A qt of oil every 700 miles and the service engine soon light off even with sure to be fouled plugs... winner!

Bonus too is that the wonderful shop has an employee with a 99 Cherokee just like my wife's (but his has double the miles, our only has 110k being 99)(My daughter & son in law has been using the Cherokee almost exclusively recently. Wife wants a new highlander... ugh, again. She barely drives. Want new truck 1st but the highlander is nice and current truck is still rock'n. Chip shortage... Inflation... thanks China & Joe)

Thanks for every one's help and suggestions. I may be late to update but a lots been going on. I do appreciate all the replies.

I hope my feed back helps others.