I suspect this has been done to death, but I’d be grateful for the forum’s definitive opinion on the subject of oil level as measured by dip-stick.
I have a 2010 NC 1.8 with just under 58K.
It’s (obviously) a bit of a garage queen, with most of its miles being summer/dry days. We did take it to the Algarve in summer 2022……from Ireland via Spain….and had zero issues.
I have both types of dip-stick, and I find the oil level is above the MAX mark, by about the same distance as the distance between the MAX and MINIMUM marks.
( easier to see on the flat perforated updated dip-stick).
Measured some 15 minutes after switching off, following a short drive.
I believe ( please correct me if this is wrong) that the distance between MIN & MAX represents about 0.8 litres.
Therefore, my engine may be 0.8litres overfilled??
I also believe, from reading this forum- again correct me if I’m wrong- that the NC engine has better longevity when the oil level is kept at, or a little above the MAX mark on the dip-stick?
My questions are:
Is the 0.8l (apparent) overfill acceptable? Or will this do damage?
Is there an actual overfill…… or is the NC dip-stick just not correctly calibrated?
My June 2010 car has been serviced annually ( therefore approx 5K oil changes since I bought it in December 2010 in Preston, with 18 miles on the clock.
I am no mechanic…… and apologise for my naivety and lack of knowledge.
I am however interested in learning and would appreciate your advice/thoughts.
I keep my oil level approx 4mm above the upper hole on the flat dipstick. I’ve never experienced oil starvation issue.
From what I’ve read (on t’internet) too much oil ain’t necessarily a good thing. I’d be inclined to think 0.8 litre is a bit too much but no doubt one of our in house specialists will be along soon to offer their opinion.
Too much oil could be frothed up by the rotating crank, apparently…
Read it again when the engine is cold, preferably left overnight.
If it reads that far over as you suggest its way overfull. About 2mm ish over the full mark is where I keep mine, flat dipstick👍
The first thing is to check the actual length of the two dipsticks from the seating point in the block to the full marks. Are they the same? You can put them side by side to see if they align.
To avoid any reading errors try using a tissue to see exactly where the level is.
Just a bit over filled is not a problem. Overfilling becomes a big issue when the oil level is so high as to allow the oil bath to reach the moving parts. A spinning crankshaft touching the top of an oil bath will whip the oil and create a foam that reduces the lubrication properties. So too much oil can cause oil starvation issues as the aerated oil does not pump or flow well.
It is usual for manufacturers to allow for a little over and underfilling with their dipsticks - to allow for temperature, vehicle angle and human error. They also generally go from the low mark to the full mark in about the ammount you could typically buy in a small bottle.
BMW electronic gauges typically advise to add a one litre bottle when the gauge says empty. Your Mazda probably wants less than this with a smaller overall capacity, a pint (0.6l) would be fine - 0.8l sounds reasonable, but I have never measured - but that does not mean that another 0.8l will equate to the same distance on the dipstick. The gauge will not be linear.
If you are over filled, the easiest way to extract some is with a pump that sucks out the dipstick. Lidl and other places sell these for about £10, and are a quick and clean way to pull some/almost all the oil out the sump. But when checking levels, do leave the car sitting level for several hours - temperature greatly affects things, as does the time taken for everything to settle.
1 inch overfilled is too much in my opinion. A quarter inch is ok.
Not like an aunt of mine that assumed filling the engine with oil literally meant filling the engine till you could see the oil level in the filler cap .
Sorry yes I commented off topic as well. Not had mine long but when I changed the oil I made sure to put in a little extra based on what I’d read. Reads a couple of mm above the top hole on the stick but no more than that.
Thanks to all for comments…,
So to summarise 2-3 mm above the maximum mark WHEN COLD is satisfactory?
Am I correct in saying that when I checked the level yesterday just after a drive ( ie engine at normal operating temperature), the apparent “overfill” (9mm above MAX) was due to the fact that the engine/oil was hot??
So the level hot will be greater than the level cold?
I always thought one should check the oil level when the car was cold- why does Mazda suggest checking 15 mins after switching off after the engine has been at operating temp?
I’ve always ignored that advice, old school for me is read it preferably the next day when the engine is cold.
Whenever I’ve read it after a run, say 15-30 mins after the oil still hasn’t all settled back to the sump but has say 12 hours later.
Some will say different to what I’ve told you, been doing it now on NC past and present for over 10 years and keeping that oil slightly over the full mark
Bought my first NC from a man in Sheffield who’s well known in the MX-5 world, his words keep the oil slightly above the full mark and it’ll be fine.
Many years ago I finally fixed the tiny, tiny coolant leak on our old woody Mini traveller, such that even on a short journey it achieved pressure and the temp gauge read correctly, dead centre in the middle when normal instead of previously always near cold.
SWMBO panicked on seeing this novel feature. So when she reached work she put half a pint of water from her drinking bottle into the engine. When she got home again that afternoon she mentioned this.
Now for the sad part of the story. As well as new hoses and some solder on the radiator l put on a “new” second-hand head with nicely fitting valves for better compression and new stem seals for much less blue smoke, and a couple of Kraus-bond pellets in each piston in a vain hope of persuading the rings they had a better fit. Job done and it felt like a new car. I was chuffed at a very quick cheap repair.
So it was with a deep sinking feeling I tactfully as possible asked her to show me where she put the water…
She was right, it was in the engine, not the radiator.
Fortunately the engine was still hot, so the Duckhams-green mayonnaise came out quite quickly. And a couple of oil flushes later it still worked, except a bit more clattery and smokey than before.
It continued leaving a blue trail for another five years or so before I managed to sell it!
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