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MG MGF Technical - Have I done any damage ???

Just changed my oil and oil filter.
Thought I'd change my fuel filter whilst I had the engine hatch open. Changed the filter and started the engine to check for any leaks. After 20 seconds, I realised I hadn't re-filled the engine with oil.

Could I have done any damage with the engine running without oil - as mentioned, it was for only 20 seconds.

I know, I'm a dimwit - a very worried dimwit at that. Sounds okay but do you think I should get it checked out.

Please settle my mind.


Not good new :-(

you have prolly caused some damage, but it should be wear related and if the engine runs fine with oil and doesn't show any lights then it will be prolly OK - but you will have scrubbed 20->30k of the engine life.
Will Munns

If it was only briefly for 20 sec as you say and didn't rev the engine then you probably are more or less ok. Obviously the less time run the better.

When you start an engine after leaving it in the garage for 2 week when on holiday all the oil is in the sump. It needs to get out of sump round the pump and up to cam and circulate, so this takes a moment, not as long as 20 secs though. If you changed the oil there still will be a covering on the parts clinging to surface which needs to be replaced by the oil from sump.

I have seen old adverts for oil additives such as STP where they drain the oil and drive the car round, and the stp car keeps going and the other one grinds to a halt but it took a hell of a time and this was being driven round the circuit.

Its not good but not "oh boy" either.

When you change the oil in some cars, the oil pressure can take up to 4 secs before the oil light goes out. It does take a little time for the oil pump to prime itself so an engine will run without oil pressure at the very start anyway. The oil pump has to pump oil first into the oil filter and then on to other parts of the engine.

The engines critical moving parts like the crankshaft, camshafts, etc, still will have oil left on them. How long the oil will stay on these surface will depend on friction and heat and contact pressue.

If the engine sounds very different to normal then that is not a good sign. If it sounds as normal, then maybe not too much damage has been done.

What oil was in the engine when you drained it and was the engine cold when you restarted it without oil.?

HTH (somehow)


They say you learn more from your mistakes than your successes!

Way back in the 60's when I did my first ever oil change I poured all the oil in without having put the sump plug back.

My feet were swimming in fresh oil.

The next problem was how to get to Halfords to get another can - hey ho.

Oh, I reckon you'll get away with it Ok.

John Thomas

The car was started from cold. Only got 28k on the clock - how do I tell if I've knackered it.

Will dash lights appear etc. Wierd noises etc.

I'm scared now !!!

If you've knackered it then the oil light may stay on, the engine will sound clattery, won't rev freely etc etc.

The oil is pumped into the bearings and so creates a high pressure film, this means that the crank is never in contact with the bearings, if you ran it without oil then the hard crank meets the soft metal of the bearing shell, if you have 'just' worn these a little then you are prolly OK. As stated above, it's reving the engine that puts large stresses on these parts, so you prolly get away with it.

Good luck - but if you have shafted it then it's time to start the steep learning curve of engine stripping and rebuilding - and then you can make it better than ever, with balanced everything and a nicely ported head...
Will Munns

Didn't rev it - just started it, went to look at the fuel filter then thought, sh1t - I haven't put the oil in the engine yet.
I'm gutted - had her from new and have always taken care of her - now I've gone and nearly siezed her up.

The sump plug was off and the oil filter was also off. Oviously oil was running out of the filter connection.

Girlfriend is now mad at me as I've gone in to complete decline - even took the car for a spin to listen for anything unusual but to be honest, I don't know what it sounded like before !!!

Is it worth taking it to a garage to get checked over - not sure what tests they can do though. Any suggestions.

basicly theres nowt to check, just drive it as before and put it down to experence, you've prolly put 20k's wear into the bearings, but this engine should make it to 150k without hastle, so you'll most lightly sell it or upgrade it well before then
Will Munns

OK, sh*t happens.
Don't worry, I think _this_ will never happen again to you and you can't turn back the clock.

Over to fun :) and other guys madness.

>Way back in the 60's when I did my first ever oil change I poured all the oil in without having put the sump plug back.

No need to going back so far with my very first oil change at the MGF.

Late 1998.
Me idiot _thought_ .. (Engineers always _think_ before they start works !!)

Why removing the engine cover and refill oil through the cam cover ?
I proudly founded a big funnel made from a 2 Litre plastic bottle. (cut the bottom and just pushed the small thread end _sealed_ into the filler beside the coolant header tank. Oil dip stick not removed, btw.

Then filled the funnel quickly with two liters best engine oil.
I read at the BBS it will run slow, OK lets see how long it takes _thought_ the engineer.

Minutes went .. nothing of the level dropped. I had a nearer look and saw the dip stick pipe and dip stick ...
Ahhh Bingo, that's it !!!
The dip stip restricts the oil flow, Dieter pull it off.

I did.... and was happy seeing the oil level drop now.
But suddenly the oil poored out through the dip stick hole down on the garage floor!!!
Errr, put it back quickly to stop it escaping.
Hummm, I need to wait until the 2 liters go down between dip stick and pipe ??
Had nuff with it half an hour later with more than 1 Litre left in the funnel.
I tried to pull off the filed funnel quickly from the filler hole and seal it below with the left hand.
Err, while you all are rolling on the floor, .... I think you can imagine what happenend with another half litre while pulling out the funnel to rescue the expensive oil.

Now laugh on ;-)


I would be pretty confident that you will have caused no damage if the only ran it for 20 seconds and (most importantly) the engine was under no load and no chance for the temperature to build up. Despite draining the oil you will still had had some oil coating the vital surafes and this will work fine for the short time of the run.

I remember seeing a “snake oil” salesman demonstrating how good his PTFE fluid was at protecting a running engine that had no oil.

If it still sounds OK then it probably is. A buggered engine makes some very unpleasant sounds!
PA Beet

A good point about the bearings. The Crankshaft bearings are constructed in layers and the outer layer is a soft coating. Lack of oil may score this coating which will start a longer term wearing as minute particles will have a place to get stuck in to and do there job.

I just changed my oil a week ago and like you I added it from the oil filler next to the dip stick.
I knew that it was a small hole to get the oil down and I removed the dip stick to allow air in for the oil to drain. I started to pour it in slowly but now slowly enough. I filled the funnel above the neck of the filler hole and it started to pour out of the dip stick hole Arrgghh!
Luckly I only spilled very little before I realised what was happening. Next time, pour slowly and don't let oil get above the level of the filler neck. Live and Loin!

from now on you should only use top quality engine oils for your car. Just to give it that little extra protection.
Gook Luck.


I'm using Castrol GTX Modern, (as always).

I am tempted to add some Lucas Engine stabiliser which I put in my diesel campervan.

Do you think additives are a good idea ???

Will Munns

This thread was discussed between 11/05/2005 and 12/05/2005

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