mx5cartalk.com

Hey guys,

Lately I've noticed my NA doing a really odd thing. I check oil levels regularly each month, and only about 3 weeks after my last oil change, I noticed that there wasn't any oil on the dipstick at all. I was scared (no doubt), so immediately refilled. Poured in about 200-300 mls of oil and checked the dipstick again. It read close to full. What the

That was probably a month ago....I checked the oil tonight again, and whaddaya know....it's done the same thing. No oil on the dipstick, but oil pressure still reads normal when driving.

I haven't topped up the oil yet tonight, as I've just gotten home and waiting for the car to cool down. But any thoughts on what this could be?

only check your oil when the engine is dead cold, ie: first thing in the morning, any time the engine has been running recently will give you a false reading.

AJ wrote:only check your oil when the engine is dead cold, ie: first thing in the morning, any time the engine has been running recently will give you a false reading.

Not the truth
If you engine has been running the It is best to place it on level ground for at least 3 miniutes before checking the oil level. this gives ample time for the Hot oil to return to the sump.


If you engine is using oil ( not leaking like the Exxon valdez) then It is more than likly burning it
and the oil is going out the tail pipe. ( in such a small amount at a time that is won't be noticable)

The cause's of this are
1) worn oil control rings
2) worn Valve guides or Guide seals
3) worn compresion rings causing excess blow by ( meaning excess crakecase pressure)
4) Sustain High RPM causing high crankcase pressure

A small amount of oil use is normal for the internal combustion engine
but with modern engine design the us of oil between oil change intervals
is so small that the average person would not know that there oil is low

If you do a lot of small trips ( under 5 kay ) every day , Your oil level will go up (???)
the reson for it is that the oil gets contaminated with the fuel that is trying to be burnt
and because of the short trips the engine oil wont reach the temp that is required to burn of the excess hydrocarbons ( petrol )

It is a good Idea to check your oil when the engine has done 50 KM and is nice and hot

deez wrote:...and only about 3 weeks after my last oil change, I noticed that there wasn't any oil on the dipstick at all.

Did you change to a different type of oil such as a very thin synthetic

recently when I changed the cams & installed an enlarged intake. the rubber hose connecting to the breather hole on the cam cover was somewhat old & tatty. This was also replaced.

I stopped using lots of oil after that. Could this be a factor?

Have you had a look on the underside of the engine to see if there's any signs of oil leakage? I had a similar issue which turned out to be a leaky seal - only when I brake harder than normal did I notice the OPG dip and then return to normal after I stopped. If it's been leaking for a while it probably won't be gleamy but would have dirt and dust stuck to what ever the oil has leaked on. My front cross member had a black padding about half a cm thick when my engine came out .

Thanks for the suggestions and advice guys, very appreciated.

JBT wrote:

deez wrote:...and only about 3 weeks after my last oil change, I noticed that there wasn't any oil on the dipstick at all.

Did you change to a different type of oil such as a very thin synthetic

I did actually....it's a Castrol Edge but quite thin, can't remember how thin exactly but what effect would this have?

StanTheMan wrote:recently when I changed the cams & installed an enlarged intake. the rubber hose connecting to the breather hole on the cam cover was somewhat old & tatty. This was also replaced.

I stopped using lots of oil after that. Could this be a factor?

Hmmm very hard to tell whether this is the issue but I will take a look at the hose and see if its worn, thanks Stefan.

Patty wrote:Have you had a look on the underside of the engine to see if there's any signs of oil leakage? .

Nope, underside is clean which is what befuddled me in the first place

AJ wrote:
If you engine is using oil ( not leaking like the Exxon valdez) then It is more than likly burning it
and the oil is going out the tail pipe. ( in such a small amount at a time that is won't be noticable)

The cause's of this are
1) worn oil control rings
2) worn Valve guides or Guide seals
3) worn compresion rings causing excess blow by ( meaning excess crakecase pressure)
4) Sustain High RPM causing high crankcase pressure

With more thought I do think that it is burning the oil and expending it through the exhaust. I don't notice any distinct smell when driving but when I stop or idle, it is quite smelly and possibly is the burnt oil. But in terms of what the reasons could be that you've listed above, #4 wouldn't be it. That leaves #1 to #3: which I don't really understand either as the motor had been previously reconditioned/rebuilt (both top and bottom end) by Mania about a year ago. What can I do to isolate which of the above it could be?

deez wrote:

JBT wrote:

deez wrote:...and only about 3 weeks after my last oil change, I noticed that there wasn't any oil on the dipstick at all.

Did you change to a different type of oil such as a very thin synthetic

I did actually....it's a Castrol Edge but quite thin, can't remember how thin exactly but what effect would this have?

I've seen it happen before with those oils in the older cars. Try changing to something like Castrol Magnatec and see if things improve. If the engine is not long out of a rebuild, it could also have slightly glazed cylinders.

Cool thanks will check this out, cheers JBT

Bit of a nub question, but if my car pours white smoke under throttle does that mean its running a bit too rich? If so how should I rectify it?

deez wrote:Cool thanks will check this out, cheers JBT

Bit of a nub question, but if my car pours white smoke under throttle does that mean its running a bit too rich? If so how should I rectify it?

A rich mixture tends to create a darker (black) exhaust.

Each 'smoke' has a distinct smell to go with the colour.
In my experience, white 'smoke' could be coolant or possibly oil.

I would recommend you take it to a knowledgeable person or a mechanic.

deez wrote:Hey guys,

Lately I've noticed my NA doing a really odd thing. I check oil levels regularly each month, and only about 3 weeks after my last oil change, I noticed that there wasn't any oil on the dipstick at all. I was scared (no doubt), so immediately refilled. Poured in about 200-300 mls of oil and checked the dipstick again. It read close to full. What the

That was probably a month ago....I checked the oil tonight again, and whaddaya know....it's done the same thing. No oil on the dipstick, but oil pressure still reads normal when driving.

I haven't topped up the oil yet tonight, as I've just gotten home and waiting for the car to cool down. But any thoughts on what this could be?

Im sorry to drag up an old thread but this exact thing just happened to me, i checked my oil today and it showed nothing on the dipstick!

I was freaked out, jacked up the car, sump plug in, check, oil leak?, no, check, put in nearly 1 litre of oil i had lying around and now im way over full on the dipstick!

This is very strange IMO, got me stumped, I use Shell helix ultra which i changed 3 weeks ago, exaclty as the OP did.

If I use a 10W-30 multi-grade oil, I burn about 2000ml per 5000km.
If I use a 15w-40 multi-grade oil, I burn about 1000ml per 5000km.
I am currently trying a penrite 15W-60 and I ain't burnt a drop in 2000km.

Since I have a engine that has done 170,000km, I am happy to admit I have worn engine inturnals and use thicker oils.

My last BP had 245,000km on it and burnt 1000ml per 1000km using 40W-70. Man that engine was loose and free revving.

Old engines burn oil. Find a grade that suits to minimize this.

Well ive just (today) gone and bought a 10w-40 as i was using 5w-30 helix ultra which is probably a bit thin in hindsight with 155k on my engine, but im still stumped as to the original issue of my dipstick showing zilch them way over full after adding about 800mls, dosnt seem right IMO.

I must have burnt some oil in the last three weeks i admit, being so hot as well wouldnt help, but ive never come across a dry sump in three weeks!

Anyway im going to do an oil filter change in the hope of getting some of this excess oil out as i dont want to be undoing the sump bolt and trying to reinsert it whilst oils pissing out.

don;t pull the filter off to lower the oil, it won't be any different to removing the sump plug.

just empty the oil from the sump plug, then either fill it with fresh oil (preferable) or if you must, catch the drained oil in a clean container and then top it back up with that.

ForceMajeure wrote:but im still stumped as to the original issue of my dipstick showing zilch them way over full after adding about 800mls, dosnt seem right IMO.

low to high on the dipstick is 800ml.

about 1000ml sits inside the engine when hot. 3000ml in the sump when hot. if you check it straight after stopping the car, it will give you a lower reading that what is the actual amount in the engine. wait 5 mins and check.

if an engine has burnt 500ml of oil, it'll only have 2500ml in the sump when hot. it may not show up at all on the dipstick when hot.

BP engine will run on as little as 2000ml of oil. but that doens't leave alot in reserve for surging from g forces etc.