Beardman

So I noticed my oil was a little low last week and topped it off. Well I go to check it again this week and it's almost a quart low again. Granted I do drive it about 600 miles a week. Just noticed this today. What looks like black spray paint is actually oil coming out of my exhaust... I do have a slow leak from oil pan as well so that will be fixed asap. I changed the gasket about 3 months ago but didn't use rtv sooo guess I'll order a new gasket and do it again. Thinking about ordering a new oil pan and bolts as well. But back to the oil spraying my drive way...wtf

ezone

That's probably just soot mixed with water, not engine oil.
Is it running rich? Getting crappy gas mileage?



How big is the leak at the oil pan?

How many miles on the engine?
What sort of oil has it been using?
What sort of air filter is on it?...or has been on it for half of its lifetime?
What do the spark plugs look like?
How is the condition of the PCV valve and related hoses/tubing/pipe?

How much work ($) are you willing to do to the engine to reduce oil usage?

Beardman

Thanks for the reply and good to know that's not oil lol.

The leak isnt bad at all being I do not ever see more than a quarter size spot after sitting all night. Mileage is 271k. I use Mobil 1 synthetic. Air filter is aftermarket, was on when I got it in November. Plugs are 2 months old, Ngk. It does smell a little rich but mpg is good, around 32 average. I'm willing to put some money and work in it. Already did a HG job a couple months ago so might as well dump more money in it if I'm keeping it.

Wankenstein

Keep monitoring oil and as Ezone stated inspect or repalce PCV valve.

Have a helper start your car while you watch the tail pipe..look for dark blue-ish plume and smell of oil. Afterwards take your car for a drive (15 minutes or more) and have helper follow you in their car and look for smoke from tail pipe. Do several quick accelerations and decelerations every few minutes.

The engine could be burning oil and not show signs from exhaust. Read this: https://www.amsoil.com/techservicesb...onsumption.pdf
Also, you may want to switch to conventional oil and the next weight up (40w). Conventional does not burn off as quickly as synthetic.

ezone

With the mileage you say, I would expect it to need re-ringed, plus do valve stem seals while the head is off.
CAI/SRI?

Problem with high flow/lower quality air filtration-- there could be significant ring and cylinder wall wear due to the filter allowing excessive particulate matter (dirt) to pass through......When you had the head off before, did you happen to notice if the original honing crosshatch marks were still clearly visible in all of the cylinder walls?

So you know very little of the cars history/use/abuse/maintenance?
Were the old plugs caked with thick ash buildup?
This leads me to believe the exhaust has no working catalytic converter and you smell raw exhaust....because most people can't discern rich or lean by smell, and if the cat is actually working the exhaust wouldn't stink.



If you are running 600 miles per week,
how many miles per quart of oil consumed? 1000? More? Can you keep up with the rate of oil loss? You can buy an awful lot of oil for what it costs to go through the engine again.....
Or maybe.... you can find used engines pretty cheap, prep it at your leisure, then drop it in the car when you're ready.


To add to turds reply, oil smoke diagnosis is the usual way to figure out the most likely cause of oil consumption (burning).....but a catalytic converter that is hot and working correctly can hide a lot of oil smoke.
Typical:
Smokes at higher RPM: rings.
Smokes during periods of high vacuum (long deceleration w/closed throttle, or extended idle time then blip the gas pedal): valve stem seals.


Switching oil weight may or may not have the desired effect on many modern engines, they don't always react the way old engines used to.

Modern engines tend to use ultra low tension piston rings which may not be able to scrape the film of thicker oil down off of the cylinder walls, the rings can skate right over that thicker oil and push it up into the combustion chamber to be burned. Thinner high quality oils like a 0w20 are better able to resist coking in the ring lands and can actually go to work slowly cleaning carbon buildup from the rings to gradually reduce oil consumption.
I was able to cut the oil consumption in my GFs Saturn in half by using better oil, but it took a loooong time to do it.
If your oil control rings are already stuck in their grooves (or worn out) and the engine is drinking oil rapidly, this is not any sort of quick solution.....and even thicker oil may not slow it down much.

Wankenstein

OP: May have either a gutted cat (internal screens knocked out) or a straight-pipe...cat converter removed completely.

Roughly which year(s) is/are considered the start of modern engines with tighter tolerances? Does a 6th gen engine qualify as a modern engine?

ezone

It was a generalization.

People who grew up with pre-70s cars (for many now it's their parents, grandparents) got used to pouring thicker oil in to slow consumption as the cylinder walls wore away (thank high tension rings for that) and thicker oil could quiet some of the knock noises of loose bearings.
People still want to do that....but the old school mentality doesn't always work with new school modern tech.

Low(er) tension rings probably became the norm in the 70s as engineers strived to reduce internal friction. Newer tech has reduced ring tension even more, made rings thinner, moved the rings up the piston ever closer to the combustion chamber, pistons got shorter and lighter.....cylinders have become even rounder (tighter tolerances, machining tech advances).....

Tech has allowed tremendous gains in efficiency and longevity, but at the same time engines have become much less forgiving of incorrect fluids, neglect, overheating, etc.

Wankenstein

Thanks.

When my son was going through engine swap issues last years with his '07 Mazda 3 the first engine swapped in was a direct replacement Mazda (Ford) duratec 2.3L and it developed (or already had) high oil consumption within a month and ultimately rod knock soon after. During internet searches at that time I read several post that said avoid using thicker oil due to the tight clearances between the main bearings and crankshaft. The recommended oil for that engine is 5w-20. I recall the late 70's Toyota's that I owned recommended 50w oil (Celica GT).