When is an oil leak not an oil leak?

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nzkiwiman

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#160230 29-Dec-2014 08:27

I have a 96 Honda Civic (which I have talked about before with my water in the boot issue)
Every 6 months it gets a service and a WOF which includes an oil change and filter. In my last service (August) the mechanic said it was very close to being out of oil. Being a Saturday he wasn't able to look too hard for me at the cause of the issue

So I made a mental note (aka, Google Calendar reminder) to check the oil level every two weeks
Every two weeks my oil level according to the dip stick is empty, there is practically nothing on it. So I have been filling it up with oil (about 1 -1.5 litres)
Next week, same story.

I have checked the drive way for signs of oil, made sure that when I start the car it isn't coughing smoke

Without any more information, anyone know what could be going on?

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Mad Scientist
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#1205263 29-Dec-2014 08:32

head gasket?

tdgeek

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#1205264 29-Dec-2014 08:34

It could be just wear. If there is no leak, the oil may be leaking slowly enough when driving, in the bores and guides, so it is slowly burning oil. You may not notice the smoke. Possible that it may on;y leak when the engine is on, and some pressure in the crackcase.

tdgeek

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#1205267 29-Dec-2014 08:35

joker97: head gasket?

Wouldn't that cause a leak that he can see, which it appears he can't? Or it leaks into the cooling system, but if that was the case, for how long its been, this thread would be in the "Whats a Good Car To Buy" forum!

kenkeniff

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#1205268 29-Dec-2014 08:36

joker97: head gasket?

Either that or overheating / burning oil. Notice much smoke coming out the exhaust?

FYI it's best to measure oil cold (I.e after sitting overnight on flat surface before starting)

RunningMan

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#1205270 29-Dec-2014 08:42

How many kms are you driving in the time it takes to use that oil?

Does it use it when not driving - say if you don't use the car for a day?

What grade oil are you using?

Check the inside of the exhaust pipe and the panelwork near where the exhaust exits - this will be covered in oily sooty film if it's burning a horrendous amount of oil.

frankv

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#1205280 29-Dec-2014 09:15

That's a lot of oil to be using. First thing I'd do would be to check it every week instead of every 2 weeks.

There are a couple of things that could be happening:

1. As others have said, you could be burning oil (i.e. piston rings are had it), in which case you should probably see blue smoke, especially when you put your foot on the gas after coming down a hill.
2. It could be a leak, but that seems unlikely if there's no oil on the garage floor. It's still possible though... it might only be leaking when the oil is under pressure (i.e. engine is running) and being caught somewhere. Look around the engine for dirty, oily patches, especially near joins.
3. Leaking head gasket. Check inside the oil filler cap... do you see a white sludge (water in the oil)? Check the water... do you see an oily film? Also check the water level in the radiator (not the the overflow catch bottle). If there's a leak, it may be pushing water out of the radiator, which in turn could get very expensive.

Frank

Zippity

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#1205302 29-Dec-2014 09:43

Get a friend to follow you for a couple of miles, when you next go for a drive.

Let them tell you if smoke is coming out of the exhaust.

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nzkiwiman

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#1205306 29-Dec-2014 09:44

Cheers all, I'll do another check over the weekend and see if I can spot anything in other places.

Hard to know if the car is smoking when I am driving, since unless the smoke is visible in the rear view mirror I can't see it.
No issues present when I fill it with oil that I can see

I'll get the mechanic to check in February when the car next goes in for a service, getting it in before mid January is going to be tricky.

Maybe it is time for me to start looking at another car however ... even though aside from this issue the car works well

Jase2985

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#1205307 29-Dec-2014 09:48

nzkiwiman: Hard to know if the car is smoking when I am driving, since unless the smoke is visible in the rear view mirror I can't see it.

get a friend to follow you and give it a bit of stick while staying inside the road rules/speed limit and get then to tell you what they see

what grade/type of oil are you using?

tdgeek

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#1205309 29-Dec-2014 09:52

Yep. Go to open road, 100kph, when road is clear and safe, take foot off the gas, when you get to 50k, gas back on, no need to floor it. Oil seeping down the bore will be burnt off in a puff of smoke. In regular driving it will also burn off, but it may be pretty minor and not noticeable, but it will all add up over a few weeks

nzkiwiman

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#1205396 29-Dec-2014 11:14

One weekend road trip out to Outram with someone following it is then.
Good to know however that if oil is burning, then it can do so without actually being seen.

Using Castrol Magnatec Engine Oil - 10W-40
Not sure what grade the mechanic uses, the internet tells me either 5W-30 or 10W-40 for my car and I couldn't find 5W-30 the first time I went to get some. Hopefully I am not causing more issues

Jase2985

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#1205401 29-Dec-2014 11:34

if its burning a bit i would try 15w40 and see if that helps

garbonzai

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#1205407 29-Dec-2014 11:53

Bad PCV valve (positive crankcase ventilation) is a possibility???

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#1205432 29-Dec-2014 12:18

Jase2985: if its burning a bit i would try 15w40 and see if that helps

he says all 4 litres of oil gone in days. that's a lot

TLD

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#1205433 29-Dec-2014 12:19

garbonzai: Bad PVC valve (positive crankcase ventilation) is a possibility???

I've seen old diesel engines run out of control burning oil vapour from the crankcase vent.

I worked 37 years at Ford UK's Research & Engineering Centre (now called Product Development) in Essex, the first three years in Environmental test where we did cold start tests. The engines were on pallets so we could get up to eight of them in each cold room, and every day they had to be run up, have clean oil and a freshly charged battery.

It was the old Dorset diesel that would run out of control. One of these disintegrated leaving bits of crankcase and bell-housing embedded in the soundproof wall covering, so the smart thing was to run when you realized a big diesel was doing >5,000rpm, but we had one brave mechanic who rushed in and pulled out the crankcase vent saving the engine. Exciting times.

The OP's civic could have worn rings as advised, or worn or disintegrated valve stem seals. The latter could be an easy fix, and I've seen it done without taking the head off, but there will be a trick to preventing the valve dropping into the cylinder when the collets are removed.

You could get a compression check to test bores and rings. I am very surprised there is no smoke with the amount of oil you say you are using. Heck, I go ages between checking oil levels on our two cars (a mid nineties Civic, and 2001 3.5 petrol Pajero) but I seldom need to put any oil in when I do check. You have to love Japanese motor vehicles :-)

Trevor Dennis
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