Oil levels:just how far over the F is too much?

I tried looking in the archives for precise information. I'm unsure if I should add to an old discussion or start a new one: this is one of the few times I've participated in a group discussion. (Please let me know if I have it wrong.)

Question: We have bought a 2002 Miata, (called MX5 in Australia) and I am just a little worried about what might be excess oil, damaging the engine. (The last owner might have slightly overfilled the oil.)

The level on the dipstick reads above the full level, about 7-8mm above the F line. The oil pressure gauge reads half way between the half-way mark and the next mark (next mark is at one o'clock.)

Just exactly how far in millimetres (or parts of an inch) over the F line will cause problems?: I was under the impression car engines had an oil pressure relief valve to avoid engine damage. Perhaps not?

Otherwise we are well pleased with our purchase.

Silver MX5 /Miata

Reply to
Red Zircon
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The oil pressure indicator has two positions only. No pressure and pressure.

Overfilling can cause the oil to foam, as it can be whipped by the crankshaft if overfilled too much. Extreme overfilling will cause serious, easily noticeable internal damage.

Generally, one side of the dipstick reads higher than the other. On my 99, ~3-1/2 US qts. with a filter change produces a full oil level, with one side below the line, and one side above.

4 quarts total is safe in most cases.

As far as the oil level is concerned, drain the excess out. Remove, drain, and reinstall the old filter as many times as necessary to bring the oil level to normal if you do not want to remove the drain plug. Either method is messy. Pour the excess oil into a clean jar to measure the quantity.Then when the level is correct, operate the engine over its rpm range while driving. If no excess engine vibration is encountered, it's very unlikely that engine damage occurred.

Reply to
Chuck
8mm I would not worry about. You may get a little leakage if the sump gasket or some other seal is on the way out, but probably nothing bad will happen.
Reply to
Mal Osborne

I had the same problem. The US owner's manual specifies 4 US Quarts. Actual capacity is 3 1/2 Qts.

No need to drain the oil. I used the Mityvac that I usually use to bleed brakes to suck the extra oil out of the dipstick tube.

http://65.16.243.140/catalog_pages/_English/downloads/MV6817.jpg

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Reply to
Natman

Thanks for the thoughtful replies. I will do some reading about the mysterious dipstick, I recall seeing some other info here about the levels being different on opposite sides.

Oil appears normal without froth, and underneath there is no sign of leakage. I'll be keeping an eye on it. The car is going in for its

40,000 first major service soon: my chance to ask some more questions.

The Mityvac sounds like a fuss-free way to get the level down, especially since there is so little room under the car. I'll also investigate the oil pressure gauge, which, if it only has an on and an off display, sounds like it's little more use than eye candy: my father would have laughed himself silly if he saw this, as he liked to meticulously measure just about everything.

Reply to
Red Zircon

Your father was a good man ;-) Mazda has been lambasted for their odd looking 'idiot light' actually it's worse, it doesn't light up bright red when it's too late like an idiot light. Anyway, lots of people change it out for a proper or near proper gauge / sending unit. You can find out lots more about this and absolutely anything miata related at miata.net . Seems like someone was getting a miata.com up and going too but the dot net site is incredible for sure.

Chris

99BBB
Reply to
Chris D'Agnolo

With regard to the dipstick issue. I have a 96 and it is my considered opinion that the dipstick scrapes the sides of the tube on the way down and often smears oil on one side of the stick, giving a false reading.

Read the lowest perpendicular demarcation between oil and no-oil. That is where the sump level really is. The rest of the oil is on the stick from scraping on the sides. Be very careful reading new oil. Move the stick around until the sun glint tells you where the perpendicular dividing line is located. If the side you are looking at is all smeared with oil, turn the stick over and read that side. That side may also have some oil on the edges, but you should be able to see the demarcation line clearly. I forget, does the stick have holes? If the hole is filled, the oil is above that mark. All dipsticks should have at least two holes -- only way to accurately read a dipstick. I think my Miata doesn't have holes but my MPV does.

Reply to
my_two_cent

Why not put holes in the dipstick. Use the measurements Above/Below the fill that you have on the MPV. Can't hurt.

Reply to
Remove This

I think the idea of drilling holes is a great idea, as the dipstick is hard (misleading?) to read depending on which side you're looking at. Oil readings on each side usually vary form each other. Drill holes would have to be kept small: the last thing I need is the bottom of the dipstick breaking off while driving!

I also think the oil pressure gauge actually works. I've taken a few photos and a short movie to prove to myself that the needle is really showing different pressures. We'll see . . . perhaps it just my boundless optimism created by this beautifully-balanced car. I'll take or one two photos more, and if I'm convinced the gauge works I will post the photos and movie.

Reply to
Red Zircon

My '94 Aussie spec MX5 has a proper analog oil gauge, maybe it was just certain years, or certain countries, or certain years in certain countries that had the crap one.

Reply to
Mal Osborne

They started the idiot gauge in 95 and kept it until 2006.

Leon

Reply to
Leon van Dommelen

Until 2005.

Reply to
Leon van Dommelen

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