Strange Oil Consumption/Burn

[gregnash]

So I may be writing this a bit prematurely but trying to figure things out before anything bad happens.

Changed my oil on 6/26 to 8.5qts of Valvoline Premium Blue 15w-40 with a NAPA GOLD 1515 filter. This was the first time I had changed the oil since I purchased my truck back in October of last year and then I used a generic 10w-30.

Now she does the typical "cruiser territory marking" but nothing major, a few drops here and there and when I drained the 10w-30 it did not look or smell funk and there was about 8qts of oil when I drained it.

Since 6/26 I have driven maybe 1500 miles and never felt any power loss, bogging, etc. and she pulls just fine going up the backcountry access roads to my normal fishing spot (which she has been doing once to twice a week for the last 2 months).

However on a whim the other day I randomly got out to check the oil after getting home from being up in Reno and my dipstick showed NOTHING!!
Put the stick back in after cleaning it off and again, NOTHING! So put a quart of oil in thinking that maybe it was hot and for some reason not reading properly, let it sit for a while and came back out and it was in the middle of the normal range.

Wanting to keep an eye on it I checked again last night and same thing except it was registering the VERY BOTTOM of the stick!!! WTF!!! So I let it sit overnight to see what I got and this morning I checked it before I went to work and she is just barely above the L on the dipstick.

Now this has seriously got me worried as I have no real signs of anything funky going on!
- No excessive smoking. I get a little puff when she starts up in the morning but that is it. If the light hits the exhaust side just right you can see she smokes very VERY lightly. But that I have always attributed to her running rich since the fuel mixture screw is a bit buggered.
- No blowby. I have checked this previously and I have not had any exhaust puffing anywhere in the engine compartment nor do I have any oil in my air filter.
- Leaks. She has the typical territory markings but nothing that would be of serious concern to me. Literally I will have a small wet spot on the ground when I leave work or the house but really that is it.. She can sit at the store for an hour or two and you will see one maybe two drops on the pavement.
- Galley plug. It is still intact and no leaks around it, no weeping, nothing.

At this point I am kind of at a loss as that is a HUGE amount of oil consumption for three months of time and very little driving. So I am thinking there must be a sticky valve that is causing excessive burn. I do have some wet spots around the flywheel area (back of block) and around the oil cooler but again no excessive leaking that I can find.

Only major change that has happened is switching from a cheap 10w-30 to a nicer 15w-40, mileage been pretty much the same, no drop in power, no drop in mpg (averaging about 13mpg), and really no smell of oil burning anywhere..

Any ideas where this mysterious oil burn could be coming from?

10/'85 FJ60, desmogged, and otherwise stock with OEM components. Mileage is truly unknown, ODO says 148.5k but I bought at 147k but then again the speedo cable broke on me after 3 months of use and the PO said it has been broken on him for almost 3yrs. My estimate is that she is close to 200k.

 

[brett76]

so its lost 2 quarts in 3 months and you have leaks and are running rich? is this correct? if so i dont see any mystery

 

[gregnash]

Ok well maybe that is what my question is... On the dipstick what is the measurement between the H and L lines? If it is two quarts then there is no mystery, it just seemed real weird that it would suddenly be that low as it has had the same symptoms but never registered that low before.

 

[brett76]

yes that measurement is two quarts from the bottom of the dipstick

 

[gregnash]

WHEW!!!! Ok that makes me feel a lot better. For some reason I thought it was closer to 4qts+ so that is why I was freaking..
I am pretty sure that I have a leaky valve cover gasket and oilpan or rear main (or both) so that would account for the burn right there..

Thanks brett much appreciated!

 

[brett76]

hey no problem

 

[SteveH]

Now that you're wary, do a real test and write down the mileage and check the oil level under the same conditions. On my LCs, it seems the oil level is most consistent the dipstick about 20 minutes after shutdown. Valve stems seals can create a hard-to-determine oil burning condition, too, if nothing else is obvious.

 

[brett76]

haha about the seals. every once in a blue moon on a hard turn mine blow smoke just for a second for that very reason i always suspected. its rebuilt now though

 

[gregnash]

Yeah I would need to fix my speedo cable first to be able to accurately track the mileage.

 

[RunTrout]

I probably add a quart every 1000 miles.
Very little leakage on the ground, a little around the flywheel and main crank.
Passed emissions with flying colors about a year ago.
Pretty sure it is getting burned.

 

[SmartyPants]

You really should replace oil every 3 to 4 months regardless of mileage. Over time the oil breaks down after it has seen some use because of chemical changes from being in the engine. This can be a major cause of wear over the years.

Hth

 

[gregnash]

I have been replacing the oil about every 3 months simply due to the fact that I have no maintenance history for the truck and would like to get a few changes through it before I head back to the oil degredation based change. Really the old adage or "change your oil every 3 months or 3000 miles" is something that our fathers used to do and is not really necessary anymore. After I get another oil change into it I will go ahead and do a BlackStone Labs VOA/UOA to see how things are. Next change will run some MMO through it and another can of Seafoam to help clear out any gunk. The PO I bought it from was running some run of the mill garbage from the corner liquor store through it. I plan to take better care of her.

 

[Cruiser Jimmy]

Greg,
Keep calm and chive on! Here's a story from my 60 which you might find interesting. I had to replace my motor with a spare from a friend, did not know the condition only for him to say it ran and that was good enough for me. Later, I rebuilt the original engine and it's now back in the 60. That spare engine decided to act like a choo choo train from the PCV system (top hole on valve cover) after I took the hose off. With the engine running the oil steam was so strong that after I took the air filter cover off the air filter was soaked with oil and dripping from the gravity port at the lower half of the air box. The reason why it started doing that was I added 300 .lbs of transmission to the ass end of the cruiser The extra weight was enough to push the engine over the edge (probably ring failure) and after that is when I rebuilt the original engine. I think you're at ease with others comments from this post but it's a system/area to look at if the concern elevates in the future.